Sunday, January 11, 2015

Maintaining your own car

I was a professional service technician (mechanic) at a Ford dealer for almost 15 years.  It was my first career.  I went to trade school in Arizona to learn my skills and focused on electrical and electronic systems, driveability, and air conditioning.  I did other repairs as well.  I have some of this experience documented on my website here:

I completed a BS in Mechanical Engineering and changed careers in 1998.  However, I still do all my own car maintenance.  I have owned several makes and models over the years.  You can see most of them here:  The only things I take the car into a shop for are tires and alignment since these require machines I prefer not to invest in, although I have considered an inexpensive alignment machine.  I have also made small alignment adjustments at times.  I never buy new cars.  I prefer to let others take the depreciation and pick them up for much less just out of warranty.  I have also purchased cars that still have warranty remaining.  Car reliability follows what is called a "bath tub curve".  There is initial reliability issues early in the cars life.  After those get fixes, your reliability is at its best until wear out.

The sweet spot is somewhere between about 10k miles and 150k miles with modern cars that are well maintained.  I often drive my cars well over 150k miles.  I sold my Crown Victoria and Audi with over 250k miles on them.  I sold my XJR and XJ12 with around 150k miles on them.  Buying a new car means you have a higher probability of needing an unscheduled repair because of infant mortality.  You pay extra for that privilege.  Keeping a car too long means you need to replace parts as they wear out.

If you don't properly maintain your car however, you are asking for trouble.  If you use cheap service parts, you are also asking for trouble.

Engine Oil

I use only synthetic oil in everything I own including my lawn mower.  Once you understand just how superior synthetic oil is, you will never go back.  I saw the difference first hand in a 1982 Honda XR250 motorcycle.  This is an air cooled 4-stroke bike.  At the time I lived in Southeast Washington State where there were many sand dunes.  Soft sand really works a bikes engine hard. They get very hot.  I was using original equipment Honda oil in it.  After just 3 rides in the dunes, the oil would be noticeably thicker and very black.  I switched to synthetic (Mobil One) and I could now go 30 rides and it still looked good.  Huge difference.  After I saw that, I was convinced.  I also worked on many turbocharged engines when I was a mechanic.  I saw too many turbo failures caused by oil coking in the bearing.  Basically natural oil cannot handle heat.  Engines make heat.  So, rule #1: use only synthetic oils in all engines.

On cars that get driven at least 10k a year, and that 10k does not have excessive cold starts and very short trips in it, you can go 10k to 15k miles between oil changes if you use good synthetic oil.  I use Mobil One extended performance in most my cars.  My daily driver does get many short trips and cold operation so it gets changed much more often.  Long trips are much easier on the oil so if I take a road trip I may go more miles between changes.  I also like to monitor the oil condition.  I look for excessive blackness, moisture, and viscosity changes,

Transmission Oil

Modern cars with automatic transmissions are starting to go to longer term maintenance intervals, some claiming the life of the car.   My XJR had such a transmission.  However, at 120k miles it started doing some strange things.  It would lock up the converter and stall the engine when coming to a stop.  It happened randomly and not all that often but it was really annoying when it happened.  Sometimes it would take several attempts to get going again.  I drained the fluid to change the filter and found the fluid was very cloudy and brown.  It made a fine mud in the pan too.  Suspecting a failing converter clutch I replace the transmission torque converter, the fluid, and filter.  Just as I got the car going again it locked up.  This time I removed the valve body and disassembled it.  I found that mud all over in the valve body clogging passages and orifices and gumming everything up.  I cleaned everything thoroughly and the problem was solved.  So, I now wonder if that lifetime fluid thing really works.  


Brakes are an area of particular concern and cheap parts should never be used here.  I had an F250 truck I once installed a set on $19 front brake pads in.  The thing was dangerous after that.  It just could not stop.  I think stopping distance must have increased by at least 30%.  It was awful.  I replaced them a few months later with a good set of Hawk premium pads (about $80) and told myself never again will I use cheap pads.  Another thing cheap pads do is dirty your wheels and squeal.  Not at all worth it.  I prefer Hawk but there are other good brands as well.


Even the gas you use makes a difference.  Never try and be cheap by putting in a lower octane than the manufacturer requires.  Always go equal or higher on octane rating.  Also, don't use cheap gas, ever.  Get it from a Shell, Exxon, Mobil, BP, Chevron, etc.  I once got "premium" gas at a Hucks station and put it in my Crown Vic (which only required regular).  The car rattled bad with detonation.  Definitely NOT premium in any way.  Another time I put premium from a no-name station in my XJ8L (which requires premium).  I was on a trip and as I was driving down the highway I noticed a lack of power, surging, and very bad fuel economy (like 10mpg off).  I suspect they had made "premium" by dumping a whole bunch of alcohol in it.  While this does increase the octane rating to prevent detonation, it also has less energy and requires a different air fuel ratio.  I went ahead and continued driving until my tank was down and filled up at a Shell.  Problem solved.  Another problem you can have with cheap gas is poor maintenance of the tanks and pumps at the station which can leave dirt and other material in the fuel.  This plugs your fuel filter and can damage pumps.  The detergents in the fuel are required to keep your fuel system clean.  Back in the late 1980's we had to clean injectors on dozens of cars every week at the shop before fuels started getting the detergents they needed and injector designs improved.   Cheap gas may lack these important detergents.

These detergents not only clean the fuel system but they also help reduce carbon in the engine.  Engine carbon buildup can cause all sorts or problems.  Here is one example of a van with a bad knock that was just carbon.  We fixed this with a few bottles of water.
Don't try this unless you know what you are doing.  Be careful not to get too much water into the engine too fast.  Major engine damage can occur if done incorrectly.  With that said, I have done this to many engines before and never had a problem. You start by getting the carbon hot.  Hold the engine speed up around 3000rpm or so for several minutes.  This will make a terrible noise but there is no good way around it.  Now, find a small vacuum line that goes to a place in the intake manifold that will effect all cylinders.  A hose close to the throttle works.  While holding the engine speed above 3000 put the hose into a full water bottle and let the vacuum suck the water into the engine.  You will need to apply more throttle as the water will make the engine speed drop.  Often you will need to hit 3/4 throttle or so.  After all the water is in the engine you can let it idle again.  If the noise is still present, repeat.  The van above took 3 bottles (16oz to 20oz each) to clear up the knock.


Most modern cars use Poly-V bents that follow a long path and wrap around pulleys in different directions.  They are commonly referred to as serpentine belts because of this.  These belts are much better than the old V-belts back in the day.  They typically last 60k miles or more.  However, if you run them to failure bad things can happen.  They can get tangles up in adjacent components like hoses, wire harnesses, and other parts and rip them all apart.  Even if that does not happen you are generally stuck on the side of the road since you will often loose charging, cooling, power steering, etc.  Best to keep them in good shape.  Changing them is usually easy and most cars have a routing map under the hood in case you forget how they go on.  These belts can actually accept a certain level of cracking on the ribs and still be OK.  It is easiest to see the cracking where the belt wraps backwards over the pulley (the ribs on the outside).  If any chinks are missing replace the belt right away.  If the cracking gets too excessive change the belt.  

Cam drive belts (timing belts) are a special case.  These must be replaced at the factory specified interval.  It is best to get a complete kit when replacing them.  these kits often include all idlers, a water pump, and tensioners depending on the application.  When these belts fail, severe engine damage generally occurs.  Some engines are designed so that timing belt failure will not damage the engine.  these engines are often called free-wheeling but they are the exception not the rule.  Luckily most modern cars have gone back to chain drives but back in the 1980's and 1990's many cars had timing belts.  Changing timing belts can involve special tools and often involves at least a half day of labor or more.  


Cooling system failures are one of the most common causes of cars ending up on the side of the road.  There are many cooling hoses on most modern cars.  If you keep your coolant in good condition these hoses can often last 15 years.  However, you need to check them periodically.  If they get harder or softer replace them right away.  After about 15 years you need to really get them replaced.  In some cases you may need to replace them earlier than that.  


Some roads, like the terrible roads here in the Midwest, can really abuse your cars suspension causing premature wear and failure of wheel bearings and suspension components.  This can be dangerous!  Inspect your suspension at least yearly.  Rock the steering wheel back of forth and feel for any clunks or looseness. Raise the wheels off the ground with a floor jack and try to move the top and bottom of the wheel in and out firmly.  Modern cars with sealed wheel bearings should have no looseness.  Visually inspect all suspension bushings too.  

More to come....
I plan to add more to this so check back occasionally.

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