Dr. Gizmo Column

"Dr. Gizmo"
By Phil Arendt

No Code For Troubled Air Bags 

Question 1
Our 2010 Chevy Impala is showing that our air bags need service.  My dealer mechanic says he doesn’t get a code.  We have to bring it in again.  Shouldn’t he be able to find a code?  B.S., email

Answer 1

Yes and No.  If the air bag system is working properly a malfunction code should pop up when your technician performs tests.  The issue might be that the air bag control module has a fault.  The result is what you have experienced. 

The control module knows there is a fault and turned on the light indicating trouble.  It just does not know the source of the trouble resulting in no malfunction code.  More tests should determine why.

Collision Damage Causes Leaky Transmission 

Question 2
Several months ago I was in an accident with my 2008 Chevrolet Uplander with an automatic transmission and 3.9-engine.  My body shop repaired the body damage and they replaced parts in the driver’s side suspension and drive shaft.  Since the repair, fluid leaks from the transmission on the driver’s side where they replaced the axle drive shaft. 

I’ve returned to the body shop.  Three times, they have replaced the seal on the shaft.  It was still leaking so when I returned the third time they installed a seal from the factory.  They were confident a factory seal would fix the trouble.  It did not.  Now they want me to take the van to another shop that specializes in transmission repairs.

So far I have not had to pay for any of the extra work, but inconvenience is a big problem.  What could be wrong?  K.N.W., email

Answer 2

I’m sorry to hear of your plight.  It’s possible that there is a defect in the new axle shaft.  It’s also possible the body shop installed an incorrect shaft.  Perhaps, the seal is incorrect.  It’s also possible there is an issue inside the transmission where there is too much play in the output shaft that connects to the axle shaft.  There might be a small crack in the case where the seal mounts in the transmission. 

While this issue undoubtedly has caused much inconvenience it is a good idea to give a shop that specializes in transmission repairs a shot on curing the trouble. 

Make sure to contact your insurance company about the issue before you take the vehicle to the next shop.

Parts Swap Needed On Newly Installed Engine

Question 3
I have a 1993 Mercedes-Benz 400 SEL with a 4.2-liter V8 that I purchased two years ago.  It now has 151,000 miles.  It’s in great condition except recently the valves bent in the engine.  This has turned out to be a huge project. 

I decided to install a used engine from a junk yard.  The yard that sold it to me said it has only 25,000 miles.  When I brought it home to my shop everything matched perfectly including wiring harnesses.  I didn’t have to swap any parts with the old engine.  I installed it and it started right up and ran fine.  I drove it around the block a few times and parked it.

The problem is that the next day it would not start.  It had spark and fuel but it still did not start.  I checked the spark plugs.  They were wet with fuel.  I finally got it started but now it runs rough, misfires and backfires in the exhaust.  I’m at a loss as to why.

Do you have any suggestions?  N.T., email

Answer 3

Congratulations for tackling this project.  When complete you will beam at your accomplishment.

As for the trouble, take into consideration how long the engine probably has been sitting around at the salvage yard.  It could be 20 years.  Since you did not swap parts from the original engine to the salvage engine it’s possible some parts need replacement. 

Since the trouble appears to be caused by issues in the ignition system it might be a good idea to check the cap and rotor in both distributors.  You might find spider webs, dirt or corrosion inside them.  If so, replacing them might get your Benz on the road.  If this isn’t the trouble check the ignition coils.

Vibration Eludes Repair

Question 4
My 2000 Buick LeSabre Limited with a 3.8-liter V-6 engine shakes when accelerating.  My car is great condition.  I follow the factory maintenance schedule to the letter.  

I took the car to my local repair shop.  A mechanic found cracks in the front axle boots.  He said all the grease had run out of the constant velocity joints.  He also found that one tie-rod in the steering was bad and the motor mounts were bad.  He also checked over the engine and transmission. He said there are no problems with either.

My mechanic replaced all the bad parts all to no avail.  The vibration continues.  Once I reach cruising speed, the vibration stops.  Do you have any suggestions?  R.M., email

Answer 4

Since the engine and transmission are in good shape and all the worn parts have been replaced the best advice I can provide is to replace the car.  I’m just kidding.  At this point ask your technician to consider checking the tires and wheels.  It’s possible the wheels need balancing.  It’s also possible a tire or wheel has excessive run-out or is bent.  There might even be a broken belt within a tire.  Since the issue is during acceleration it might be a good idea to focus on the front tires.  They are the drive wheels so an issue such as a bent wheel could cause vibrations.

Original Equipment Part Might Fix A/C

Question 5
The air conditioning in my 2007 Volkswagen Jetta with a 5-cylinder engine is not cooling as it should.  When stopped at a light the temperature of the air blowing from the vents warms.  Also, the temperature gauge on the dash goes up.  Once I start moving the engine temperature goes down and the a/c cools down.  At cruising speeds everything works fine. 

I went to my local repair shop.  A technician found that the electric fans by the radiator are not working properly.  One does not work at all and the other makes unusual noises.  He suggested that I take the car to a dealership because he does not work on VWs that often. 

I went to a dealership.  Their mechanic determined that new fans were needed so I returned to my local shop.

My local shop installed new fans.  They did not work at all so he returned them and installed another new set of fans.  They don’t work either.  He says he is going to ask his parts supply house to get parts from another source.  Does this sound right to you?  N.M.B., email

Answer 5

Yes.  He correctly diagnosed the problem the first time you brought the vehicle to his shop.  His diagnosis was verified by a dealership technician who likely used factory diagnostic equipment to determine the cause of the trouble.

There is one thing your local independent shop technician might consider.  He is having problems with the parts from his supplier.  He might consider that aftermarket replacement parts will not work in your car.  Sometimes when this occurs installing a factory original equipment part cures the issue.

Low Voltage Disables Hybrid Vehicle

Question 6
I have been out of the country for nearly two months.  Upon my return my 2005 Toyota Prius will not start.  Normally when I start the car a ready light turns on in the dash but it is not turning on.  Is there anything I can do to start the car?  R.P., email

Answer 6

The issue might be caused by low battery voltage in the hybrid battery so consider having the car towed to a shop equipped to repair it.

There are two batteries.  One is the hybrid battery pack that is high voltage and could cause serious injury or worse if proper safety precautions are not followed.  It powers the motors that start the engine and power the electric motor.  The other battery is an auxiliary battery that powers accessories such as the instrument cluster.  If either battery lacks power the vehicle may not start.

If you are not inclined to have the car towed consider calling a service that can jump the auxiliary battery.  In the engine bay fuse panel is a connection for the positive jumper cable.  A good ground connection is at the strut tower near the fuse panel.  Your service provider will make the proper connections to jump the battery but even if it is jumped the car may not start.  If so, it’s time to tow it to a shop.

Thank you for all the 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@hotmail.com. 08/11/2014 ® DR. GIZMO © 1989 - Present