"Dr. Gizmo"
By Phil Arendt
Trouble Starts With A Bang
Question
1
I
was backing out of my garage in my 1999 Ford Explorer when I heard a bang. After that, reverse no longer worked.
Thankfully
my Explorer is not my primary transportation.
I use it to drive to a train station where I hop a train to my place of
employment. With the recent nice weather
I’ve been walking or riding my bike to the station.
My
Explorer has 110,000 miles and is in great shape. I’ve owned it since it was new. I use it to go to the train and on
trips. I’d hate to get rid of it. Is there a minor problem in the transmission
or does it need a major overhaul? B.R.,
e-mail
Answer
1
It’s
possible a minor problem is at the root of the condition. In the transmission there is a part called a
reverse band. Sometimes it pops off a
pin. If this is all that has happened, a
complete overhaul is not necessary.
Obviously, the vehicle needs to go to a repair shop where a transmission
specialist can determine the exact cause of the trouble.
Do
not attempt to drive the vehicle. Doing
so may cause damage. Also, it may be
wise to enlist the aid of a flat-bed tow vehicle to have your impaired vehicle
transported to a shop. Towing on the
wheels could cause transmission damage.
Glitch
In Electronic Suspension System
Question
2
I
own a 2008 Cadillac Escalade that I purchased in 2010. Shortly after the purchase the “Service
Suspension System” light has intermittently been blinking on and off. I took the vehicle to a repair shop where a
technician found trouble codes for a failing exhaust valve but when he tested
the valve it worked fine so he did not replace it. He also tested an air compressor but that is
working fine too. He said that his test
equipment can command the system to work but the car does not do it on its
own. He did replace a relay but that
has not solved the trouble.
I
don’t notice any problem in vehicle handling or ride when the light turns
on. Do you have any suggestions? A.N.R., e-mail
Answer
2
You
could trade your vehicle for a new Escalade.
That will resolve the trouble.
All kidding aside, it appears tests have determined that the system wiring
is working as designed as well as components.
One part that can cause trouble such as this is the control module. Since everything else seems to be operating correctly
ask your technician to consider there might be a glitch in the module. If so, replacement and programming should
cure the trouble once and for all.
On
Track To Repair
Question
3
The check engine light
is on in my 6-cylinder Ford Taurus with 44, 000 miles and the engine idle is
rough. I replaced the spark plugs in
cylinders 1, 2, & 3 with no improvement.
Also, I used special cleaners in the gasoline for several hundred miles
with no change. I also had the other
spark plugs checked and a new battery installed. After all of this, the engine light went out
for several days.
The check engine light
has returned. I had the computer codes
read at a parts store. The partsman came up with codes PO174 and PO2272 which I
understand indicates a bad oxygen sensor. Apparently there are four on my car.
How can I determine which
one is bad? Are the hand-held testers
used by the parts store as accurate as the ones at the big shops and dealers? Does the test make sense to you? L.P., email
Answer
3
To answer the last question first, indeed your questions
make sense.
There are many reasons for
the codes. One condition that could
cause the codes is a high oil level in the engine. Another is the dipstick may not be fully
seated in the tube. There also could be
air leaks in the air induction ducts, intake manifold or exhaust system. Perhaps the hose for the PVC valve is leaking. Check for problems such as these before
replacing oxygen sensors.
Also, generally test
equipment diagnostic trouble codes will identify a failed sensor by bank and test
results can determine whether the sensor before the catalytic converter or after
the converter is at fault.
More than likely the test
equipment used at the parts store is not as sophisticated as the equipment
commonly utilized at successful independent and dealership shops. Generally, independent repair shops utilize
aftermarket test equipment that is not manufacturer specific. They are designed to test systems in multiple
vehicle makes and models. While the
equipment is very good there often are software impairments that imped
diagnosis. Some large independent repair
shops owners often do invest in aftermarket and manufacture specific diagnostic
equipment used by dealer technicians.
The most accurate test
equipment is used at dealership shops.
The units are manufacturer specific and usually perform better than aftermarket
test equipment.
Oil
Change Habits Under Scrutiny
Question
4
You
seem to be one of the declining numbers of proponents of the 3,000 mile oil
change. Even big oil companies have said
that manufactures recommendations are all we need to follow. They say more frequent oil changes is a waste
of oil.
I
used to drain perfectly good oil religiously every 3,000 miles. Now I go according to the maintenance
schedule. Is it really necessary to
change the oil as often as you suggest?
S.L., Johnsburg, IL.
Answer
4
Over
the years I have read many engineering studies on oil. The engineers in the studies admit they
change the oil in their vehicles at 3,000 mile intervals even though studies
prove engine oil performance has improved over the years. Based on the studies and off- the-record
engineer advice I change the oil and filter every 3,000 miles. If I slip up, the preventive maintenance
chore might linger until 4,000 miles. I often
keep vehicles until the body falls apart up to 300,000 miles without major
engine repairs. The reason they last so
long is the simple oil and filter change plus new air filters. The oil drains from the engine nearly as
clean as it goes in. The reason it does
is the inside of the engine is nearly free of abrasive dirt. Air and oil filters do a good job of
preventing dirt from entering the engine as it gulps huge amounts of air, but they
do not stop all of the dirt. The oil has
to prevent dirt that slips passed filters from grinding away at the engine. Also, oil filters have a bypass valve that
opens once the filter is full of dirt.
If it didn’t, oil, as dirty as it is would not circulate through the
engine. If this happened the engine
would seize to a full stop.
Oil
is in top condition when it is new, but it wears out. It does a good job of preventing engine wear,
but it has an additives package that stabilizes the oil. As the additives wear, the oil loses its
ability to prevent wear plus the longer the oil is in the engine the more dirt
it gathers as it wears out. To prevent oil
and engine wear it is necessary to keep the oil supply as fresh as
possible. Since cars are such a huge
expense I rather change the oil and filter rather than buy new cars every few
years.
You
may ask why I only purchase new cars. One
reason I resist the purchase of used vehicles is the uncertainty of past regular
and frequent oil change preventive maintenance.
Despite this, a reasonable length test drive and a visual examination of
the dipstick can reveal previous owner oil change habits. It can also determine if a service was
performed on the engine to hide the fact a previous owner did not change the
oil and filter on a frequent and regular basis.
Whistling
Sound Signals Trouble
Question
5
I
have a 2000 Ford Windstar with a 3.8-liter engine and 197,000 miles. Recently, the check engine light turned on
and I heard a whistling sound from the engine.
It also started to run rough. I
took the vehicle to my reliable local repair shop where a mechanic found a
crack in the intake manifold. He
replaced it and the engine was back to normal.
Last
week the check engine light turned on again.
Since the engine was running normally I did not return to my local
repair shop. Instead I went to an auto
supply store where the engine module computer was tested for trouble
codes. The employee found a code for a
lean running condition on bank number two.
He said this might be caused by a vacuum leak at the manifold that just
was replaced. Before I take the van back
to my repair shop do you think my mechanic did something wrong? Is there anything else that could cause the
problem? T.E., e-mail
Answer
5
It
is possible the seals on the newly installed manifold are leaking, but if a
seal is not installed correctly generally it leaks immediately and not a couple
of weeks later, but anything is possible.
It’s also possible the manifold has a defect. Consider returning to your reliable repair
shop to have the trouble checked.
Perhaps
there is a leaky vacuum line. Maybe one
of the oxygen sensors has a fault. It’s
also possible there is a clogged fuel injector or failed injector. Any of these conditions could cause a lean
running condition. If the manifold is
leaking, more than likely your mechanic will step up and repair the leak under
warranty. If there is another issue, he
will find it.
Heavy
Key Ring Might Cause Trouble
Question
6
My
2001 Oldsmobile Alero with a 2.4 engine stalls when I hit the gas pedal. If I accelerate slowly the engine does not
stall. Sometimes when I stomp on the gas
pedal the engine hesitates a few times and then it stalls. This is really nerve-wracking when trying to
pass another car. So far no warning
lights are on in the dash. Also, I had
the car checked at a local shop but no trouble codes are in the engine
module.
I
have been driving with this problem for months.
I have found that if I hold the ignition keys still when I accelerate
the car does not stall. Do you think
there is a loose wire or something is wrong in the ignition key switch? M.B.L., e-mail
Answer
6
It
is possible there is an issue in the ignition switch. Over the years I have found that vehicle
operators who have everything from small tool kits to three cell flashlights on
their key rings have ignition switch trouble more often than drivers with lean
key rings. If your key ring weighs a
ton, it is time to reduce the number of items to bare minimum.
To
fix the trouble a technician might find a loose or corroded wiring terminal in
the steering column or in the lower portion of the dash. It’s also possible the ignition switch has an
internal fault. If so, replacement will
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 drgizmo@drgizmo.ws. 4/06/2012 ® DR. GIZMO © 1989-2012
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