"Dr. Gizmo"
By Phil Arendt
Four-Wheel-Drive Fails To Engage
Question 1
The four-wheel-drive warning
light is on in my 2007 Chevrolet Avalanche and four-wheel-drive does not work.
I take great care of my
truck with frequent oil and filter changes.
I follow the recommended services in my owner manual and the advice of
the manager at my local independent repair shop. I don’t go off-road but do use
four-wheel-drive on roads when they are slick.
The last time I used it was in a blinding rain and that’s when the light
turned on. Is this going to cost a
bundle to repair? H.B.R., email
Answer 1
Rain, what’s that? Also, if you have children, it might cost
your first born to fix the trouble. All
kidding aside this problem likely is due to a failed actuator, motor or
wiring. The trouble likely is not caused
by a mechanical failure such as a failed transfer case or differential as you
did not state that you hear unusual sounds such as grinding noises which
usually cost an arm and leg to fix.
Sloshing Sound Baffles
Motorist
Question 2
Recently, I purchased a 2010
Buick Enclave. It’s in like new
condition and has 17,000 miles. It runs
and drives great, but I have one complaint.
Often, I hear sloshing sounds from the rear of the vehicle. I assume the noise is from the gas tank. I have never heard this sound in any vehicle
I have previously owned, but I have never owned a Buick. Is this normal? M.M.R., email
Answer 2
Congratulations on your
recent purchase. You might have paid
extra for the sloshing sounds, but the condition is not normal. You might hear sloshing gasoline after an
emergency stop but under normal driving conditions sloshing should be
minimal. There are baffles inside the
gas tank that reduce sloshing and splashing.
Apparently, a baffle is loose, misaligned or detached.
To find out for sure if this
is the problem, a technician first should verify the fuel tank is the source of
the noise. Once this is confirmed he
needs to drain the tank and remove it from the vehicle. Then he removes the fuel pump module so he
can visually inspect the tank interior.
If a baffle is loose, misaligned or detached replacing the tank is the
cure.
Once you have made an
appointment with a shop, be sure the gas tank is near empty on your appointment
date. I’m sure your shop will advise you
about this issue in further detail.
Deodorant No Cure For Stinky
Exhaust
Question 3I own a 2008 Chevrolet Cobalt with a 2.2-liter engine and automatic transmission. I purchased it six months ago. It’s in excellent condition and runs great. The trouble is the exhaust fumes smell like rotten eggs. At first I did not notice the odor but more recently since spring I’ve noticed the odor especially when the windows are open. At first I thought the smell was from other cars and I was shocked when I realized it was mine. It’s embarrassing. I’ve noticed other drivers looking at my car at stops lights.
I talked with a mechanic
about the trouble. He suggested that the
catalytic converter might need replacement and to take the car to a dealership
to have the work done under warranty.
I took his advice and went
to a dealership. It was told that the
catalytic converter is fine and the gasoline I use is the cause. They told me to switch to a different gas
station but the odor is not gone. Do you
think the gasoline is the cause or is it something else? Can I add something to the gas to get rid of
the odor? D., email
Answer 3
Sure, add any deodorant or
lemons to the fuel tank. All kidding
aside, the likely cause of the odor is sulfur.
Some fuels contain higher than average sulfur however, there are
regulations as to how much sulfur can be in gasoline. Gasoline that contains close to the limit and
don’t have additives to combat sulfur are more prone to develop rotten egg odors
than gasoline that contains the additives to reduce the odor.
Since deodorant or lemons
are not an option, consider purchasing top tier gasoline. Top tier gasoline meets higher standards for
fuel additives but may not contain less sulfur.
Fortunately, detergent additives in top tier fuels are better at
controlling sulfur odors.
To find out which brands of
fuel are top tier go to www.toptiergas.com. Once you have decided which brand to
purchase, drive until your tank is nearly empty. Fill the tank with top tier fuel. As you drive, the odor should diminish and
might be completely gone after two or three tanks of top tier fuel. Of course, to make sure the odor does not
return, continue to burn top tier fuel.
Adjustment Needed
Question 4
A few days ago I replaced
the master cylinder in my 1991 Toyota Celica.
Since then I have noticed after I drive a while the front brakes drag
and get excessively hot. I have checked
everything at the calipers. They are
fine. I’ve also checked the hoses and
lines for damage and there are no bent or kinked lines.
I don’t think trapped air is
the problem but I bled the system three times to make sure.
I’m about to return the
master cylinder to my auto parts store but before I do I want your
opinion. Do you think the master
cylinder is defective? G.G., email
Answer 4
Perhaps it is. However, the push rod between master cylinder
and brake booster might need adjustment.
You may need to shorten the length by giving it a few turns. To do a proper adjustment, refer to a repair
manual. Once the adjustment is correct,
the trouble might be resolved. If not,
it’s time to exchange the master cylinder for another.
Yikes! Brakes Failed At
Intersection
Question 5Recently, the antilock brake warning light turned on in my 1999 Chevrolet Cavalier. I took the car to a repair shop where they determined that the module was bad. They replaced it and all was well. Three days later when I applied the brakes I was slowing to a stop when the brake pedal went to the floor and the car barely stopped. I almost went into a busy intersection. I was able to safely drive the car to the side of the road, shaken but not injured. Immediately, I called my repair shop. They sent a tow truck.
The next day the shop called
to tell me a brake line at the rear of the vehicle had popped. They inspected all of the lines and suggested
that I have all the flexible lines at the wheels replaced due to cracks.
I’m a college student who is
short on funds. Did the mechanic have to
remove the line to replace the module?
If so, did the mechanic do something incorrect? Is it necessary to replace all of the
lines? T.B.A., email
Answer 5
The module is at the front
of the vehicle. There is no need for a
technician to fiddle with hoses at the rear wheels.
Each wheel has a flexible
rubber hose that contains brake fluid.
More likely than not, due to vehicle age, the rubber has
deteriorated. When you applied the
brakes, hydraulic pressure caused the brake hose to fail and brake fluid
escaped from the system. The pressure
loss impaired braking power but at least you had one front and one rear wheel
stopping the car due to vehicle design.
As for replacing all of the
hoses, it’s a good idea. If one hose was
suffering from age related degradation, it is likely the remaining hoses are
suffering as well. As a preventive
measure against another failure, consider replacing all of them.
Stuck In Four-Wheel-Drive
Question 6
When making tight turns in
my 2002 GMC Yukon the entire front of the vehicle shudders. I asked my local shop about the trouble. The manager said it sounds like the
four-wheel-drive is engaged. As far as I
know it is not engaged. He said I should
bring the vehicle in to have it checked out.
Does what the manager said
sound right to you? R.B., email
Answer 6
Yes indeed. It is possible the front drive portion of the
four-wheel-drive system is engaged. When
this occurs on dry pavement torque builds in the driveline and causes the wheels
to stop, shudder and slip especially in tight turns. There are instances when torque energy
becomes so great a vehicle will not move except in reverse gear. In such incidents driving a long distance in
reverse gear dissipates the torque so the vehicle can move forward. This likely will not happen in your vehicle
as long as the wheels continue to shudder and slip in response to the power of
torque.
The trouble might be due to
electrical faults but more than likely an actuator is stuck and will not
disengage the system. Replacing the
actuator might be a lasting cure. Ask
your favorite technician to consider these thoughts when you take the vehicle
for repairs.
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. 07/16/2012 ® DR. GIZMO © 1989-2012
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