Fog Light Kit

Note at the end of this all about fog lamps article will be links to some of the most popular fog light kits and replacement halogen bulbs for factory installed systems. But first didn’t you ever wonder about your cars fog lights. Why they are constructed different than headlights. Why they are mounted in positions that are far lower than regular headlamps.

When I first started to drive at 16, no cars had factory mounted driving lights. This was an aftermarket accessory that I quickly added to my vehicle so it would look cool. To my surprise not only did they look cool but they actually came in handy. I found myself driving through foggy areas often as I lived near cranberry bogs in a low lying area of New Jersey.

A side note when you are adding auxiliary lights you must make sure that your alternator and wiring are heavy duty enough to handle the increased wattage. In the case of my 1974 Dodge charger the fog lights were too much for the standard wiring and charging system. After an electrical fire that melted all the lighting circuit components I upgraded the alternator and installed new heavy gauge wiring. After the upgrades all was good.

Difference between fog lights and headlights

Ordinary headlights do not penetrate the fog very well. The focus of a powerful beam of light directly at the fog reflects most of the light back to the driver. You can verify this by switching from your high beams to your low beams on a foggy night. You can see fore yourself which one actually provides the best distance of site.

Wide beam fog lamp

I’m not a scientist but I believe it’s because the fog is made of water molecules and these tiny droplets of water are what actually reflects the beam of light back in the drivers face. Fog lights in most cases use halogen bulbs but instead of using a wide powerful beam they attempt to sneak a flat beam of light under the blanket of fog. This is one of the main reasons that fog lights are mounted as low as possible on the vehicle.

Fog is actually like a cloud that hangs near the ground. This is often generated from temperature differentials. Cold air meets the warm ground or body of warmer water for example. So much like clouds in the sky fog forms when the air becomes saturated with moisture. As a result water forms out of the air into a fine mist of water droplets. Fog can get very dense and obscure visibility quickly as it forms with little warning.

H3 Halogen Bulb

Nowadays more often than not fog lights will come standard with your vehicle and not needed to be added using aftermarket parts. In the case of my current vehicle which is a 2004 Chevrolet Blazer my fog lights are factor installed.

On my blazer you can only use the fog light if the headlights are on the low beam settings. If your fog lights are on and you switch on the high beams the fog lights are automatically turned off. In my example above when you are trying to drive in foggy conditions the brighter your headlights are the worst your vision becomes.

My Chevy Blazer is set up so the fog lights only operate if the headlights are in the low beam setting. Replacement halogen bulbs can vary greatly in price from store to store. My Blazer uses the H3 halogen bulbs. I have provided a link to it below for your convenience.

For more of the latest articles on this blog this next link takes you back to the homepage from this page about fog lights. If you’re interested in more articles about technical subsystems related to cars I have a section dedicated to automobile technology you might find interesting.

300ZX AC Problems

I had a few 300ZX air-conditioning problems with my 1988 Z. in case these are problems that are inherent in these vehicles I will describe them below. When I got this car it had r12 Freon in the system as you would expect from an older vehicle such as this.

Me being an automotive mechanic that has converted many systems, I was prepared to do the same to this vehicle. I did have a 1 pound can of r-12 Freon that I used to bring the system up to its proper level when I first got the car. I was expecting that someday I would have to convert the system to the new R-134a. To my surprise I did have problems with the air-conditioning system but never had a refrigerant problem so I never converted the system.

I have put a page together on my you fix cars website that has more tips and directions for people that want to convert from r12 to 134a. There is more to the procedure then just dumping one and installing the other. In fact if you do not follow the recommended procedure your air-conditioning system will probably not blow cold for long.

Nissan blower motor problems

My 300ZX was equipped with Nissan’s continuously variable airflow control. This means that there were more settings than just medium-low and high. And the system was actually quite complicated. There was a fan control amplifier which utilized a series of transistor-based circuits that continuously controlled the airflow blown out by the blower.

Blower motor pushing air through evaporator

This allowed for a selection of infinitely variable airflow rates. The fan control amplifier is housed in the blower motor case itself. There is a heat sink radiating plate mounted on the amplifier assembly and it is placed in the airflow of the blower motor to provide cooling to the transistors to prevent electrical heat failure.

When my 300ZX reached about 12 years old I started experiencing intermittent airflow operation and I could hear the blower motor kicking on and off. When I pulled out the fan control amplifier I didn’t see any melting or actually any problems but it was the culprit and needed to be replaced. I got the replacement part from the junkyard and never had any other blower motor problems with the car.

Nissan AC problems

I did have 300ZX air-conditioning problems that were not a Freon related issues. At first I thought it was, because the problem was the air would start off cold and then get warmer the longer you used the AC system. This is a typical symptom of an evaporator freezing up. One day I ran the air-conditioner until it started to warm up and I pulled the evaporator cover off to find a solid block of ice.

It’s funny that when the evaporator is frozen solid into a block of ice that the air actually gets warmer. But it is true because the airflow through the cooling fins is reduced and diverted around the evaporator assembly instead of flowing through it.

Nissan AC expansion valve

On a 300ZX air-conditioning system the compressor cycles on and off to maintain the proper evaporator temperature. When the evaporator temperature falls below a specific point the Thermo control amplifier interrupts the compressor operation by disconnecting power. When the evaporator temperature rises above the specification power is restored to the compressor.

The late 80′s Nissan 3 L V-6 air-conditioning system uses an expansion valve with a capillary tube that provides the temperature input from the evaporator. On my 300ZX the capillary tube leads to a bulb on the end that attaches via a clip to the evaporator fins. I’m not sure how it happened but it became detached and was just laying in the evaporator case and was not providing the proper input temperature. I cleaned the temperature bulb and reattached it to the evaporator fins and the problem was solved.

On this auto repair information blog I have written a lot about my 300ZX and the repairs that were needed. This was one of my favorite cars but also required the most work out of any automobile I had ever owned. It was also my first Nissan so it taught me a few lessons about Japanese cars. I have also written many air-conditioning articles and you can head back to the main page and see the latest auto repair blog posts.

AC Compressor

When Car AC repairs are required one of the worst-case scenarios is having to replace the AC compressor due to an internal failure. When I say internal failure I’m talking about the compressor coming apart inside and spreading metal throughout the air-conditioning system.

Often both professional and driveway mechanics will just try to replace the compressor by bolting on a new part. This is an invitation to further repair and ongoing problems with the air-conditioning system. The small metal pieces that are hiding throughout the lines and other components will circulate and continue to cause problems.

Proper compressor diagnosis

In most cases when a compressor suffers internal damage the telltale sign would be the noise generated from the compressor itself while the clutch is engaged. You do want to take some time and verify that the noise is actually coming from the AC compressor and not another belt driven accessory.

Before condemning the compressor to be the faulty component it is a good idea to confirm this by fully charging the system and take some pressure readings. When a compressor has internal damage it is unable to pressurize the system properly.

Normal pressure readings on a summer day would be about 35 PSI on the low side. And about 150 to 200 PSI on the high side. These pressure differentials are created by the compressor itself. If the low side pressure is high and the high side pressure is low with a full charge this is a sign of a defective compressor.

AC compressor replacement procedures

The problem with replacing a bad compressor that is damaged internally is removing all a little metal particles from the system. Often both driveway and professional mechanics would like to just blow compressed air through the lines in the hopes that all of the pieces will be dislodged and removed.

The reason this doesn’t work is because the system contains an oil charge. This oil sticks to the inside surface of all of the lines and tubes. The metal particles then stick to this oily film. This is why the proper procedure is to use a liquid flushing agent to flush the AC system.

The AC flush chemical has similar properties to brake clean. When the liquid is forced through the system the oil is washed out and the alcohol base of the AC flush will dry the interior surfaces of the lines. With no more sticky oil film holding the little metal particles they are easily removed.

AC Dryer

One of the components that cannot be completely cleaned with the AC flush procedure is the receiver drier. This component should be replaced along with the orifice tube when you are replacing the AC compressor itself. Flushing the AC system will not remove metal particles from the orifice tube or the receiver drier.

If someone replaces your AC compressor for you make sure that you’re getting your money’s worth and that they are performing the proper procedure. Ask them about how they will flush the system and how long they will guarantee the replacement of the compressor. This will often force them to take the extra step and do the job properly.

Feel free to visit my you fix cars website for a detailed list of the steps that should be followed when replacing car ac compressor. Or you can return to the auto repair information blog homepage for more of the latest posts to this blog.

Beam Torque Wrench

Professional mechanics, driveway mechanics and most people that work on cars hate taking the time to torque bolts properly. As a professional mechanic myself I don’t like it either. First you have to break out your torque wrench and maybe even get it calibrated.

Next you have to find the actual torque specification in an online car repair manual for the bolt that you are going to tighten. Then you’ll have to take extra care and get your torque wrench on the bolt and finally torque it to specification. This is a lot of effort when you can just put a wrench on that very same bolt and just pull on it for two grunts and a groan.

Not applying proper bolt torque would be considered a shortcut that can reduce the quality of the car repair and may cause a repeat failure or additional repairs to be performed. This is more critical in some areas such as intake manifold bolts. If these are not torqued properly they can allow coolant to run inside the engine and damage expensive internal parts.

Add to this the fact that many modern aluminum intakes now use composite gaskets that are primarily made of plastic and this increases the necessity for proper bolt torque. On some of these modern aluminum intake manifolds the actual torque specification is very low and the pattern that you tighten the bolts down in is extremely critical.

Why do we have to torque bolts

All metals whether they are aluminum, steel or even titanium have some elastic properties to them. This property means the bolt can be stretched and compressed. When the bolt is stretched a clamping force or holding power is created due to the bolts natural tendency to want to return to its original length. This can stop the bolt from backing off even if it is exposed to lots of vibration.

Like a spring the more bolts are stretched the tighter it becomes. Keep in mind that a bolt can be stretched too far. When you have gone past this point of no return you can often feel it in the wrench. When you reached this point the pressure applied to the wrench turns the bolt further with less effort. This is your telltale sign that you have gone way too far.

Often this is when the head snaps off and leaves an extremely tight bolt with no head stuck in a hole. When this happens the repair time is increased greatly along with the troubles that may be generated by drilling and removing the broken bolt.

When you compare the amount of aggravation generated by breaking a bolt compared to the time that it would take to look up the proper torque specification and set up your torque wrench you are much better off doing it the right way.

3/8 drive click torque wrench

After being a mechanic for 25 years most often I would use my half-inch torque wrench. But now it seems that I use my 3/8 drive torque wrench even more. I have also recently had to add an inch pound torque wrench to my tool-set.

This has been an ongoing trend of bolts that are torque to a lighter specification. The good news is the cost of these tools has continued to come down. Visit my auto facts website for more information about torquing bolts and access to inexpensive bolt torque wrenches.

For more of the latest posts to this website you can get back to the homepage from this next link. I add new articles about once a week to the auto repair information blog.

Defroster grid repair kit

Rear window defroster problems can cause poor visibility through the rear glass and on some models the side view mirrors are connected to the same system. This article covers a few of the common problems with electrically operated defroster systems as well as a few facts about how it operates.

Whether you call it a window defroster, deicer or defogger what were all talking about is heating the rear glass to remove moisture particles that can collect on the glass and reduce visibility. The major components of the rear window defroster on most models will include a manually operated on off switch, one or two relays and the heating elements on the glass surface.

The front windshield uses forced air that has had the moisture removed from it by the air conditioning evaporator to dry the front and side windows with warm low humidity air. This is a more efficient method than the heated grid that is commonly mounted on the rear window glass. Therefore slower defogging should be expected.

Common rear window defroster operation

The electrical rear window defogger is one of those systems that operate basically the same on most makes and models. You may find a few models that operate differently but for the most part standard operation is the same.

By pressing the rear window defroster switch you will energize a relay that sends power to the rear heater grid assembly. On many models full battery voltage is sent to the rear grid. On models with heated side mirrors voltage may also flow to these at the same time.

On most of the systems that I have worked on I find that they are equipped with some type of timing device. Often this automatic rear window defroster timer is set for about 10 minutes. This is to prevent overheating of the glass element. It’s not very common but I have seen rear window defroster problems caused by a timer malfunction. It can heat the glass until it cracks or not turn it on at all.

Even though some rear window defrosters have this automatic shutoff feature it is still wise to turn it off manually after it has completed its task of removing fog and moisture from the inside of the glass. There is no reason to continually send voltage to the heating grid and when this is switched off more efficient battery charging is accomplished.

Common rear window defroster problems

Tester and repair kit

One of the most common problems with rear window defrosters is physical damage to the heating grid that is glued to the rear glass. Damage can be caused by objects rubbing across the inside surface of the glass or in some cases by overzealous cleaning of the inside glass surface using harsh chemicals.

When working at new car dealerships many times we found that the temporary tag that was stuck in the back windshield was glued over the defroster grid. When the customer received their permanent tag and remove the temporary they wound up damaging the electrically heated grid.

When a segment of the grid is damage it opens the circuit. This can cause the grid to become inoperative from the break point forward. An open spot in the grid can be found by using a test light or meter. With the defroster turned on voltage should be present at all points of the grid.

With one side of the test light grounded you can lightly touch the point of the test light to the grid to test for voltage. It is best to start at the voltage connection and work your way towards the ground side. If there is no voltage at all then it will be time to test the switch, fuse and circuit breaker along with any system relays.

If you do find open grids often they can be repaired with a paint like compound that is available at most part stores. For more information about car accessories and their problems you can visit the auto repair information blog homepage from this page about rear window defroster problems.

Honda Power Mirror

Power mirror problems are quite common because these automotive parts are exposed to the elements as well as stick out from the vehicle and are subject to impact damage. Factory original replacement power mirror parts can be very expensive.

Although I am not a supporter of cheap aftermarket automotive parts this is one area of the vehicle that I will make an exception. Listed below will be some of the most commonly searched for replacement power mirror parts such as the master power switch and the complete mirror motor assembly itself.

The nice thing about these systems is that they are very similar between car lines and even models. A VW electric mirror system is not that different from the one installed on my Pontiac Grand Prix. Before we get to replacing parts let’s discuss some of the more common power mirror problems.

Power mirror parts problems

Power Mirror Switch

Some power mirror parts that I see the most failure in would be the master control switch and stripped nylon gears on the electrically operated motor. In the case of my old Pontiac Grand Prix the power master switch is located on the armrest of the driver side door panel.

With the way that the roof is designed anytime it rains and I crack the driver side window water drips off of the roof line and directly into the power mirror master switch. After a few years of this happening to switch itself which is rather delicate compared to the other switches on the vehicle can become corroded and provide intermittent operation.

In some cases you are able to disassemble the switch and clean the electrical contacts. But again this switch is made rather delicate and sometimes the disassembling of the switch will lead to eventual replacement of it. The tiny springs and contacts can get lost and in some cases the plastic will just break apart and you will not be able to put it back together.

Power mirror not working

In many cases when you operate the power mirror master switch you can hear the motor running but the glass doesn’t move. The motor controls the movement of the glass in most cases with a series of small nylon gears. If the mirror is binding then the nylon gears will start to slip and eventually the little teeth will wear off.

VW Power Mirror

Back in the old days they used to offer overhaul kits and we use to replace the gears and motors as necessary. Nowadays it is more common that the manufacturers and aftermarket companies will offer a complete replacement that includes the new glass, the housing and all internal parts including a new motor.

In my opinion this is really the way to go using the aftermarket power mirror parts in a complete assembly. In most cases power mirror assemblies whether they be driver-side or passenger-side are relatively easy to replace. On many models you may have to remove the door panel to gain access to the retaining bolts.

Having a properly operating power mirror assembly is more than just a convenience. When properly adjusted these mirrors give you a view of what’s happening around you with simple eye movement to the left or right. When you have power mirror problems and you’re not able to adjust them on the fly you can have an increase in the area that you can’t see. These are most commonly known as blind spots. These blind spots can get you into trouble when you are switching lanes on the freeway.

If you are interested in more auto repair information articles this next link will take you to the blog’s home page. You can review more of my latest posts and I usually add new ones about once a week. Visit the auto repair information blog from this page about power mirror problems.

Me working on a diesel engine

Diesel fuel is a petroleum product that is not as popular in the United States as it is in other countries. As a resident of the United States and a strong believer in the benefits of diesel fuels I hope that the North American continent will someday embrace this type of fuel.

One thing that can be said about diesel is that it contains more energy per gallon than gasoline and therefore can be considered more efficient. The engine that burns this type of petroleum produces much more torque at lower RPMs because of high compression chamber ratios.

This makes it a perfect choice for trucks and trains that haul heavy loads and that will require massive amounts of torque to get that load moving.

The difference between diesel and gasoline

The fuel in a gasoline engine is ignited by a spark plug. The diesel engine uses its own high combustion chamber pressure to compress the fuel until ignites on its own. Gasoline is extremely flammable compared to diesel fuel.

The flammability of gasoline is measured using the familiar octane rating. Diesel fuel also has a measured ignition quality known as the cetane rating. Much like the octane number the cetane number is measured in a single cylinder test engine with an adjustable compression ratio.

The higher the cetane rating the shorter the ignition lag time before it is ignited by the compression stroke. An average cetane rating that can be found at the pump would be around 50. Whereas the average octane rating of gasoline would be around 87 on regular grade at the pump.

Different grades of diesel fuels

Minimum quality standards exist for diesel fuel grades. The two common grades of diesel fuel available would be number one diesel and number two. Number two is most commonly found at the fuel island in the local gas station. Number one can be blended with number two to improve starting in cold weather.

Different areas will blend the two fuels at different rates depending on how cold the climate is. The number two grade is more efficient and contains more energy. In winter months when number one is blended in it can actually reduce fuel economy.

Bio diesel fuels to me are the most interesting. These can be made from recycled restaurant grease and many different types of vegetable oils. Bio diesels fuels can be used all by themselves are blended with number one or number two grade fuels. If it can be produced cheap enough and then blended it can have very positive effects on the cost per mile.

In most cases to use a blended Bio diesel no engine modifications are required. It also does not affect the vehicles overall torque or horsepower and in turn does not reduce the vehicle’s ability to carry a payload. Research has also shown that emissions from blended Bio diesels can be lower compared to the number one and number two grade types.

As we all know the world needs to get off of fossil fuels. Solar, wind power and other cutting-edge technologies may take decades to get off the ground. Diesel fuel may be exactly what we need to bridge the gap to the future. Read more articles from this auto repair information blog. Or this next link will provide a bridge to more information about alternative fuels.

Power Window Motor

Power window problems on cars and trucks could be considered one of the most annoying problems you could have on an automobile. When you think about it how often do you actually operate the power windows on your car.

When you roll up to the drive-through window at your favorite fast food restaurant or you are going to pay a toll I’m sure you would like your window to operate properly. Many times electric window operation can become intermittent. This is even more frustrating than if it stopped working altogether.

When you have intermittent operation the tendency is to put off repair of the system until either the problem gets worse or the Windows stops working all the time. From a safety point of view you really shouldn’t put off repairs because you never know when rolling up or down that window will be important for safety reasons.

Power window systems

Power Window Parts

The power window system happens to be one accessory that really doesn’t vary that much between vehicle manufacturers or car models. The major components of an average system would be the master switch, the window lift motor, circuit breakers and relays, and the wiring that ties those items together. Oh I forgot the glass itself.

Often when the window stops working people ask me where the fuse is. Most modern power window systems do not actually have a fuse. It is more common to find a circuit breaker protecting the wiring and electrical components. A circuit breaker will automatically reset if the system overheats or pulls too much amperage.

In addition to the main circuit breaker usually there is an internal circuit breaker to protect each individual window lift motor. If one of the window switches is held too long or the window is obstructed the circuit breaker will automatically open to prevent damage to the motor.

Common problems with power windows

Master Switch

I diagnose a lot of these power window systems. The two most common problems that I find is either a defective window lift motor or a problem with the master switch. To break it down even further it is the driver side window motor that I see fail most often.

The simple fact is that the drivers side front door window is operated much more than any of the other Windows on most vehicles. This is also true with the master switch that is usually mounted on the drivers side door panel. The master switch gets more use than the other switches in the vehicle.

On my own personal vehicle the master switch is mounted flat on the driver side armrest on the door panel. I have had problems with the master switch because of its location. Water from the roof drips right onto the switch when the window is down or even partially opens. This poor design led to heavy corrosion built-up inside the switch.

I was able to save myself from replacing the switch by removing and disassembling it. I got myself some electrical contact cleaner and was able to remove all of the corrosion. I have to perform this procedure about once every two years because of this master switches poor location.

Diagnosing electric windows

Just because the driver side master switch and the driver side window lift motor are the most common failures this doesn’t mean that you will have those exact problems. Many other parts of the system are capable of failing.

When you’re starting your diagnosis of a power window system it is best to determine if the whole system is not working or maybe it’s just one window from one switch. If nothing works in the system the place to start would be with the master control switch or the main system circuit breaker.

If only some of the Windows don’t work and others do you would want to check parts that are common to the windows that are not working. From an electrical point of view you may need a wiring diagram for your specific automobile to determine what electrical parts are in common.

As an example let’s say that the right rear window is the only window not working. It does not work from the master switch or the switch on the right rear door panel. In this case it would be time to remove the door panel and inspect the power window motor that runs that window. Again an online auto repair manual will provide step-by-step diagnostic instructions to determine what the failure is.

Car Airconditioning Compressor

I get a lot of questions about car air conditioning systems not blowing cold enough. Especially during hot humid summer days. Most people would like to see frigid cold air blasting from their small dash vents instantly upon request.

Remember when your car has been baking in the sun heat is stored up in large quantities and must be removed before it starts to feel cool inside. But what if the air does not seem to get cold after 5 minutes or so?

There are many factors involved that affect the actual output temperature at the dash AC vents. To follow will be a few examples of common problems that I find when inspecting a car air conditioning system that is not performing as well as it should be.

Without a doubt the most common problem that I find is an incorrect Freon charge. The amount of Freon in the system is extremely critical. The manufacturer installs the exact amount that is required for the system to perform at its peak. This exact charge is so critical it is documented in the vehicle’s engine compartment down to the ounce.

A few ounces short of a full charge can result in inadequate cooling under high heat loads due to lack of reserve refrigerant. A telltale sign of this condition would be for a compressor clutch to cycle on and off faster than usual. The rapid clicking sound generated from this condition can usually be heard from inside the vehicle.

Sometimes when people try to recharge their system on their own they will actually overcharge the system which can cause poor cooling performance just as much as low Freon levels. In extreme examples an overcharge of refrigerant can even cause AC compressor damage and noisy operation.

Loss of AC efficiency

Car AC Condensor

Not as common as the Freon issue mentioned above but one that is common in my area at this time of the year is a radiator or a condenser that has been considerably clogged with bugs, dust and dirt, or road debris and trash.

When this junk starts to reduce the airflow that passes through the radiator and then through the condenser it can cause higher than normal high-pressure readings. This in turn can knock several degrees off of the output temperature in the interior cabin.

This is the kind of problem that slowly gets worse over time. It is very rare that people will take the time to check or clean the radiator and condenser. The fleet company I work for has made this operation part of the scheduled service operations. We have a pressure washer and we physically clean the radiator and condenser fins every 20,000 miles.

AC Test Guages

Although there are lots of other problems that can cause poor cooling the two mentioned above are ones that I find often. If you think your car air conditioning is not blowing cold enough the first step is to check the output temperature at the center duct with a thermometer.

Make sure the recirculation or max air mode is selected and the blower is on low speed. 40 – 50 degrees is perfect. On hot humid days here in south Florida 55 degrees is welcomed. Step 2 is to have a professional connect a manifold gauge set and get some high and low side pressure readings. With these readings a logical path of diagnosis can get your AC blowing cold as it should be.

I put together a repair modules section on my you fix cars website that talks about the theory and operation of car air conditioning. Understanding how the system works is very helpful for problem solving. You can also head back to this blog’s main page and get some more automotive repair information.

Battery powered fuel siphon

Sometimes although not often fuel quality problems can cause extremely hard-to-find engine drivability problems and repeat failures of fuel system components. Described below will be an effective way for you to check the basics of your fuels quality.

Keep in mind that you will need an accurate fuel sample from the vehicle you want to test. Although there are several safe ways to remove fuel from your tank I recommend that you pick up a special fuel siphon hose from your auto parts store. Or I have a link to the one pictured to the left at the bottom of the article.

You will also need a glass cylinder that is graduated in milliliters (also available below). In order to keep the testing simple it is best to use round numbers. Your graduated cylinder should hold 100 ml and have a cap to prevent tainted results. Don’t worry you do not have to be a scientist to conduct this test but you will need a gas sample and a graduated cylinder.

Why test fuel quality

Premium Fuels

Before I get into this short and sweet procedure for testing your fuel quality let’s talk about why it needs to be done sometimes. On a few occasions I have been faced with drivability problem that seemed impossible to solve that was eventually traced back to contaminated fuel.

I have also seen repeat failures of fuel pumps and related components due to excess alcohol content in the vehicle’s fuel supply. Too much alcohol in the fuel can do a lot of damage but one of the most common results is repeat fuel pump failures.

Many areas of the country use oxygenated fuel to help improve air quality. The additive that is used to oxygenate the fuel is most commonly alcohol. Chemicals such as ethanol have the same effect on the fuel system as alcohol.

If the alcohol concentration exceeds 10% by volume this can cause the engine to run lean. A lean running engine has higher combustion chamber temperatures and can increase wear to items such as spark plugs, valves and seats and the fuel system components such as pressure regulators and injector nozzles.

How to test for fuel quality

Fortunately you do not have to be a scientist to find out how much alcohol is in your fuel. Take a fuel sample from the test vehicle and fill your graduated cylinder to the 90 mL mark. Next you add 10 mL of water to the graduated cylinder to bring the total contents to 100 milliliters.

Now you snap the sealing cover over the end of your cylinder and shake the mixture thoroughly for about a minute. Then you can place to cylinder on a level surface and allow the solution to settle so that the different fluids separate. I usually wait an hour or two before I examine the cylinder.

GM fuel pump

Since water is heavier than gasoline the water will settle to the bottom of the cylinder along with the alcohol that is in the fuel. Water and petroleum products do not mix but alcohol and water will bond to each other and fall to the bottom of the cylinder.

If the fuel contains any alcohol the water level will be greater than its initial reading of 10 mL if the new watermark exceeds the 20 mL mark on the graduated cylinder that indicates a concentration of more than 10% alcohol. If there is more than 10% alcohol in your fuel it should be replaced along with your fuel filter. This will avoid any of the problems that can result from having too much alcohol in your fuel.

Note if you just want to test for water in fuel, you will need to get the fuel sample from the bottom of the tank. You can then just fill the cylinder to the 100ml mark and let it settle before observing the results.

The above method was taught to me by an automotive instructor in a General Motors training class. He provided us with one of the glass cylinders for us to take back to our shops. I don’t use it that often but when I do I find fuel quality problems about 25% of the time. For more information that might help you out of a jam you can return to see the latest posts on the auto repair information blog.

Rear Differential Cover

Rear differential maintenance and changing the fluid is not required as much these days as with many other maintenance services on modern vehicles. But completely ignoring the differential is not recommended in case problems should develop.

A regular maintenance routine includes inspecting the gear lubricant level and condition. You can check your owner’s manual for recommended intervals and your auto repair manuals for specifications as well as the types of fluids to be used.

In the case of rear wheel drive vehicles different types of gear oil are used in different makes and models. Since there is no filter inside fluid can become contaminated with metal flakes and moisture.

Most rear differentials will have magnets either mounted inside or as part of the drain plug to help remove metal particles from the circulating lubricant. In some limited slip rear differentials special lubricants that contain a friction modifier are required. Failure to use this special recommended fluid can cause drivability problems, increased wear and annoying noises.

Recommended inspection points

Axle Seals and Bearings

As with many parts on the car rubber seals are susceptible to wear and leakage. The rear differential contains a few of these lip type seals. One area to check is where the drive shaft attaches to the pinion yoke known as the pinion seal. Any fluid leak from this area should be repaired before lack of lubrication damages internal components.

Rear axle seals are also made out of rubber. A leaking rear axle seal can cause the same type of problems with lack of lubrication. But more importantly a rear axle seal leak can dump fluid onto your rear brake pads or shoes.

Differential Cover Gasket

This type of problem can increase stopping distances and cause other problems. On many rear differentials the cover that fits on the back is another point of a possible leak to develop. This is also a cover that may need to be removed for regular maintenance.

Most differential covers use a gasket. Sometimes auto mechanics will take a shortcut and replace that factory gasket with silicone. This is not a recommended procedure and can wind up causing a leak down the road.

Rear differential maintenance is important because the entire assembly does not carry more than a few quarts of lubricant. Even a small leak that goes unnoticed can cause the fluid level to be low enough to starve axle bearings and cause other problems. An occasional visual inspection of the parts mentioned above can provide an early warning and save you from expensive repair costs.

The drive train subject is not covered on the internet as much as other auto repair information subjects. I decided to put together a section dedicated to these systems on my you fix cars website. You can see this area located in the left hand navigation under manual drive trains.

CVshaft Assembly

The CV shaft rubber boots are one of the weak links in the longevity and survival of front wheel drive axles. If the boot stays intact the grease stays inside and the joint can last the life of the vehicle.

On the flip side the CV joint rubber boot can be damaged and the grease can be slung out by centrifugal force. The lack of lubrication can cause premature wear of the CV joint.

If the boot is damaged enough it can also allow water and dirt into the joint and at that point the joint and shaft will probably be ruined very quickly.

These CV shaft rubber boots need special care when you are servicing your vehicle. The following tips may save you some trouble down the road. And reduce the need to either replace the boot or replace the entire shaft assembly.

CV boot care tips

When you are using a floor jack to lift up the vehicle be aware of the angle of the axle shaft and CV joints. Consider supporting the lower control arm so that there is less stress placed on the CV joint and boot.

Never use your CV shaft, CV joint or tripod joint as a lifting point for your floor jack. In some cases it may be an easy point to grab and look strong but don’t do it! The CV shaft was not designed to lift the vehicle and can cause a huge amount of damage to the shaft itself as well as the transmission output shaft and even the wheel bearings.

CV Boot Kit

When performing a front wheel brake job or removing the wheels for balancing or rotation you can throw some shop towels over the rubber parts of the axle shaft or even precut a plastic container to protect the CV boot from accidental damage. You never know when your screwdriver will slip and puncture the boot by mistake.

The CV shaft rubber boots can be damaged by gasoline, oil and other chemicals. Take the time to make sure your CV boots are clean and dry. If they have gotten oil on them from a diy oil change or fuel from a fuel filter maintenance service make sure you clean the boot with soap and water only.

Take care of your CV boots and they will take care of you. The longer you keep them intact and in good condition the longer the whole axle shaft will last. In some cases I have seen the original CV shafts and boots last for the life of the vehicle.

If you are interested in drive train components and the care and maintenance of these important parts I have put together a repair module with lots of free information. You can visit this page on my other website and learn more about manual drive trains. For the latest post to this blog the next link will take you to the homepage were you can get some more auto repair information.

Clutch Kit Parts

My 300ZX clutch problems began with a rear main seal leak. It wasn’t long after the clutch started slipping that the Z wouldn’t move at all. When I put the vehicle up in the air to check it out I saw what was going on.

The rear main seal wasn’t leaking very much but it was enough to cause the clutch to fail. Oil and friction material such as the type that is contained on the clutch disc don’t go well together.

The clutch disc friction material actually begins to soak up the engine oil like a sponge. A slippery spongy clutch is the opposite of what you need to move the vehicle properly.

This type of clutch problem is actually quite common and happens to many manual transmission vehicles from manufacturers both foreign and domestic.

300ZX flywheel problems

I pulled the transmission and remove the clutch and pressure plate. I could see that there was some heat scoring and a bluish color to the flywheel surface. I decided to send the flywheel out to be resurfaced at a local machine shop.

OEM Clutch Kit

Since I wasn’t into racing at the time I just decided to go with a standard clutch kit that included a new pressure plate and throw out bearing. I got the flywheel back and it looked very nice. I put it all back together with the new rear main seal and although the clutch moved the vehicle it would slip under heavy loads.

I suspected that the pressure plate from the cheap clutch kit was the problem. It appeared to me that there was not enough clamping force. When I pulled the transmission back out and once again removed the clutch and pressure plate the flywheel surface was again a bluish color.

I called the supplier of the clutch kit and told them what was going on. The first question they asked was, did I have the flywheel resurfaced. They suggested I check the thickness of the flywheel to make sure it was not over machined.

I never thought to check the work of the machine shop. But that was exactly the case. They took too much off the flywheel surface and it was now undersized. After purchasing a new flywheel and talking the clutch kit supplier into sending me a new friction disc I put it back together. Problem solved the clutch had full grabbing power and no slippage.

More 300ZX clutch problems

After about two weeks of happy driving I was at a stoplight and had the clutch pedal depressed to the floor and the gear selector in first waiting for the light to turn green. I felt the clutch pedal starting to fade and the car started to move forward.

Clutch master cylinder

I popped it in neutral and pumped the clutch pedal and it returned to normal. This began to happen more often. The clutch was fading just like a brake pedal does when a brake master cylinder is failing. The clutch master cylinder is very similar to a brake system one.

Long story short after my clutch job as described above it was necessary for me to bleed the hydraulic clutch system. I got distracted and I left the master cylinder cover off for several hours. The clutch hydraulic system uses brake fluid that is considered to be hydroscopic. It absorbs moisture quickly.

With the clutch hydraulic fluid contaminated it destroyed the seals in both the slave cylinder and the clutch master cylinder. Since the hydraulic hose that connected the two cylinders was also made of rubber I decided to replace that as well. This turned out to be the most expensive clutch job I have ever seen in my 25 years in the auto repair business.

The 300ZX can be a very unforgiving automobile. I never owned a car that I loved so much and yet had so many problems with. In the defense of Nissan products, I did buy the vehicle 10 years old and with 100,000 miles on it. I expected it to be a hobby car. It actually turned out to be a vehicle that taught me a lot of lessons.

If you’re interested in what other lessons this vehicle taught me you can visit my 300ZX repairs page to see the ever growing list of what went wrong and how I fixed it. If you’re interested in seeing the latest posts this next link will take you back to the auto repair information blog.

DOT 4 Brake fluid

Checking the brake fluid is a good place to start and can tell you more about the condition of the brakes than you may realize. Brake fluid is the lifeblood of any hydraulic brake system and is responsible for proper operation.

Brake fluid not only serves as a lubricant to the many parts that it comes in contact with it also fights corrosion and rust in those components and brake lines.

On the negative side brake fluid readily absorbs moisture. This is known as a hydroscopic fluid, and is why brake fluid should be sealed properly and not stored in open containers.

Keep in mind that a mechanic should perform a complete inspection of the brake system including rotors, calipers, pads and road testing the vehicle to confirm any complaints.

But this doesn’t mean the average car owner can’t get involved with their own automobiles well-being.

Checking the brake fluid

common master cylinder

Brake fluid levels are checked at the master cylinder. Most modern master cylinders have a plastic reservoir that holds the brake fluid. These plastic reservoirs usually have markings for low and full levels.

The plastic container is just translucent enough for you to actually see through and view the actual amount of brake fluid in the container. On some models the plastic is thick enough and the fluid is so clean it can be difficult to see.

In these cases you can take a flashlight and hold it up against the reservoir while you look through on the opposite side. The flashlight will illuminate the fluid and make it easier to see the actual level.

Note that if you plan to add any fluid that it is extremely important that you clean the master cylinder before you open it. You also do not want to leave the reservoir open for a long period of time. You must keep all dirt and moisture out of the master cylinder reservoir. And only install the recommended fluid type that is indicated on the master cylinder cover.

What the brake fluid can tell you

Brake fluid should be clean and a light golden color. You can open a new container of brake fluid to get a good idea of what it is supposed to look like and then compare your own brake fluid to it. Brake fluid that is dark or thick is a sign of contamination. This bad fluid should be flushed out and replaced. Contaminated brake fluid can damage important seals in the brake system.

Another thing brake fluid level can tell you is an approximation of the amount of wear on the brake pads and shoes. This will only work on systems that have not had fluid added to them. If you brake fluid is low then inspection of the pads and shoes should be performed.

As brake pads wear the pistons extend from the calipers further too properly apply the brakes. This leaves more room in the caliper for fluid. This fluid is supplied from the reservoir.

The more the brake pads wear the more fluid is held by the calipers and the lower the master cylinder level becomes. This is just a basic rule of thumb but if you do your own maintenance and you know you have not added to the master cylinder fluid level, it can be a sign that a brake inspection is necessary.

View the latest automotive articles and post on the auto repair information blog.

Battery terminal problem

It is very frustrating when a car battery loses charge over several days of the vehicle not being used. It is also not good for the battery and if this continues to happen in many cases replacement will be necessary.

The most common cause of the battery going dead after sitting for a short while would be a drain from the electrical system on the vehicle. Most often this can be traced back to a light in the vehicle that is either left on or will not turn off automatically.

A couple of examples would be a glove box light or a trunk light. In most cases these types of courtesy lights are supposed to turn off automatically. When they don’t the car battery loses charge.

The automatic operation of these courtesy lights is controlled in most cases by a pin switch but in some older vehicles you can still find the old-fashioned mercury switch. Testing of these items is further explained below. Click on read more.

Courtesy light drains battery

Hot at all times circuit

These types of courtesy lights operate similarly to a refrigerator light. In automobiles the courtesy light is connected directly to the battery and receives power whether the ignition switch is on or off (hot at all times).

In the example of a pin switch or a mercury switch power is supplied to one side at all times. There is no drain on the battery until the circuit is completed by the switch. Note if the bulb is removed the circuit would not be completed as well.

In the case of a pin switch on a glove box or trunk lid when the plunger is depressed it opens the circuit and stops current from flowing. These are usually two or three terminal switches that are easily tested by pushing on the plunger.

Testing for battery losing charge

automotive meter

In the automobile there are some constant drains on the battery that are normal and draw small amounts of current known as a parasitic drain. An example of this would be a digital clock or even the cars computer which has a function known as stay alive memory.

When these parasitic drains become excessive the car battery loses charge and intermittent no start conditions can happen. There are several ways of performing the battery drain test. Some people use a test light connected in series with the positive terminal.

I prefer to use a multimeter or an ammeter that is connected in series with the negative cable. This is where you disconnect the negative side of the cable from the battery and connect one lead of the meter to the cable and the other lead of the meter to the battery.

A good rule of thumb is that the ammeter should read less than .25 amps with everything turned off in the vehicle including the hood light. If you need more information on how to use a meter or want to see my top picks for good ones you can visit my page about automotive meters.

Fixing a battery drain problem

It is best to remove the hood light bulb from the socket when you’re performing these types of battery drain tests. If your readings are high, especially over one amp what you can do is pull the fuses out of the car’s main fuse panel one at a time and observe the meter for any changes.

For example if you pull the courtesy fuse and the meter drops down to a normal condition you have located the circuit that contains the drain on the battery. You can then grab your wiring diagram and see what loads are on that circuit.

Inductive Pickup

An even better way of testing for a car battery losing charge is to use a meter with an inductive pickup. This allows you to leave the battery fully connected to the vehicle and place inductive probe around the positive cable connecting to the battery. This is the preferred method but not everybody has an inductive pickup ammeter or multimeter.

When a car battery loses charge several times it eventually loses its ability to recover from the low voltage condition. Batteries that are exposed to normal heavy drains such as trolling motor batteries or even marine batteries are known as deep cycle batteries. They are designed to be drained and charged several times. The standard car battery is not a deep cycle battery and therefore cannot handle this type of battery drain problem for long.

See the latest posts to this auto repair information blog. This next link takes you there from this page about what to do when the car battery looses charge.