By Phil Arendt
Foggy Headlights Need Extra Care
Question 1I'm surprised by the number of headlamp restoration products on the market. I've always assumed these plastic lenses could always be cleaned with soap and water or auto polish. I know of one person who uses toothpaste.
Is
it really beneficial to purchase a headlamp restoration product to increase the
effectiveness of the headlamps? B.D., Woodbury,
Minn.
Answer
1
No
it’s not necessary unless the lenses fog from environmental attack. The cost of headlamp capsules can put a dent
in a household budget. Due to
environmental factors headlamp capsules can fog. This greatly reduces the light projected by
the bulb impairing a driver’s night vision.
An
inexpensive way to restore the clarity of a headlamp is to use a restoration
product. They are available at many auto
supply stores. Headlamps can be harmed
by some waxes, soaps and the sun. Studies
have found carwash soaps and waxes have caused headlamps to fog so soap and wax
products used in the carwash industry have changed. Additionally, automakers have changed the
composition of headlamp capsules so they are more environmentally tolerant.
I
don’t know if toothpaste could cause a capsule to fog or clear a lens but I
would recommend not using toothpaste to restore headlamp clarity. Instead use of a restoration product is the
best route to a clear view of the road ahead.
Brake Fluid Leak Ruins Module
Question 2
I have a 1999 Chevrolet Express 1500 van that I use for work. It has a 5.0-liter engine and 127,000 miles. It’s a great work truck and over the years I have not had any trouble with it until now. The problem is the engine began to misfire and the check engine light turned on. A mechanic replaced a speed sensor because it failed tests and the speedometer was off by almost 15 miles per hour. It registered 60 mph when I actually was going 45 mph. Now I know why everyone was passing me and giving me dirty looks and threats.
Replacement
of the speed sensor did not cure the misfire.
My mechanic replaced all the spark plugs and wires. He also checked the compression and much more
but did not find anything wrong. Despite
this the misfire continues. Now he says
brake fluid is dripping on the engine computer and that might be causing the
trouble.
How
can a brake fluid leak cause such a problem? R.K.P., email Answer 2
I can understand your skepticism. After all the circuitry of an engine control module is within a sealed metal case. Unfortunately, the placement of the control module in your vehicle is under the brake master cylinder.
Brake
fluid is corrosive and the metal shell of the control module is comprised of
two pieces. The two pieces that house
the circuitry are secured together with fasteners and a seal. The seal is the part that is vulnerable to
the effects of brake fluid’s corrosive action.
When the seal fails, brake fluid enters the control module and ruins the
circuit.
To
fix this trouble it appears the brake master cylinder and the engine control
module might need replacement.
Cleaning
Parts Leads To More Trouble
Question
3
I
have a 2007 Honda Odyssey with a 3.5-liter engine and 98,000 miles. Recently, I replaced the air filter. I also cleaned the mass air flow sensor and
throttle body with chemicals specific to the different parts. On the mass air flow sensor I used air flow
sensor cleaner. To clean the throttle
body I used throttle body cleaner, an old tooth brush and shop rag soaked with
the chemical. When I was finished the
parts looked as good as new. The trouble
is that now the engine idles too high and the check engine light is on.
I
went to auto supply store for a scanner test to determine trouble codes. The parts man found code P2279. He said it indicates that there is an air
leak somewhere in the intake system. I
checked all the ducts for improper fit or loose connections but everything
looks fine.
What
am I missing? D.L., email
Answer
3
Such
trouble might be caused by air leaks at the positive crankcase ventilation
valve, brake booster, intake manifold and or the throttle body. Check all of these connections for air leaks.
Also,
in the process of cleaning the throttle body there may be a leak due to a torn
or misaligned gasket. It’s also possible
cleaning the unit with a toothbrush and shop rag damaged the unit as bristles
or cloth fibers may have contaminated it.
If so, clean it again with just the chemical and keep your fingers
crossed flushing will cure the trouble.
If
air leaks are not the cause of the trouble, further tests of the throttle body
may find it needs replacing.Battery Warning Light Shines But System Functions Normally
Question 4
The battery light is on in my 1998 BMW 528i. It has 66,000 miles, a 2.8-liter engine and 5-speed manual transmission. It’s in great condition. I bought it three years ago and it’s been running great since the purchase.
I
went to a repair shop where they checked the charging system and battery. Everything checked out fine. They did not know why the light is on even
though they did several tests. Since I
did not know how old the battery was I asked them to install a new one as a
precaution.
The
light continues to shine. Do you have
any suggestions? M.R.Y., email
Answer
4
Since
your vehicle has rolled along for many years, it is possible ground connections
have been affected by corrosion or have loosened. A check of the ground connections is in
order.
Also,
sometimes a technician will overlook the basics such as checking fuses. A blown fuse could cause the light to
illuminate. It’s possible this step has
not been done so it might be a good idea to check the fuse panels for a blown
fuse.
It’s
also possible a blown fuse will lead to a problem such as a short in a circuit
that is related to the charging system.
If so, repairing a short could resolve all of your concerns and the
light will no longer be an issue.
Cracked
Part Causes Knocking Sound
Question
5My 2002 Toyota 4Runner has developed a knocking sound. I hear it only when the automatic transmission is engaged. While I was at a quick lube a mechanic listened to it. He said it sounded as though it is coming from the transmission and not the engine.
My
truck has 138,000 miles. I bought it
new. It’s in great condition. It hasn’t given any trouble. I take good care of it with oil changes every
3,000 miles. I follow the factory severe
maintenance schedule for everything else.
The transmission engages and shifts fine. Also, the engine runs fine. Should I be worried? R.B., email
Answer
5
The
noise may not be a precursor to impending doom.
Since the knocking only occurs when the transmission is in gear it is
possible the flex plate also known as the flywheel is cracked. This is a good possibility as your vehicle
has a tendency for this issue. If so,
the transmission needs removal in order to replace the afflicted part.
Ask
your favorite technician to consider this when you visit a shop.
A/C
Takes Too Long To Kick In
Question
6The air conditioning compressor in my 2000 Jaguar S-Type takes up to 5 minutes to engage. When I turn it on it does not cool. As I drive I feel the compressor turn on and then cool air begins to blow from the vents. Sometimes I have to wait five minutes before I feel the compressor turn on.
I
went to a repair shop where many tests were done. No problems were found but the mechanic did
agree that it takes a long time for the compressor to turn on. He also said that once it engages it runs too
long. He does not know why.
Another
technician at the same shop checked over the system with the same results. He agrees the system is not operating as it
should but suggested that I wait until the trouble becomes worse or the system
quits working all together. He said when
that happens they will be able to find the cause of the trouble. I’d rather not wait.
Have
you ever heard anything like this before?
C.C., email Answer 6
Stranger things have happened. Your technicians more than likely checked system pressures. It’s also likely they ran tests on the performance of control modules and other electrical components and found they are functioning normally at the time of tests.
One
part they may want to scrutinize is the relay that turns the compressor on and
off. Tests might find it is not
performing as designed. If so,
replacement should cure the trouble.
Thanks for all of your great questions. Dr. Gizmo can’t wait to answer more.
Phil Arendt is a columnist, consultant and A.S.E.-Certified
Master Technician. Readers may send
questions to Dr. Gizmo at P.O. Box 548, Cary, IL. 60013 or e-mail address mailto:drgizmo@hotmail.com. http://www.drgizmo.ws 05/13/2013 ® DR. GIZMO © 1989 - Present
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