Complete Northwest Herald Dr. Gizmo Column For June 22, 2012

Sometimes space is limited in the newspaper so not all of the column appears every Friday.  Last week was one of those incidence.  Here is the complete column.

06/22/2012

"Dr. Gizmo"
By Phil Arendt

At Times Trans Shifter Fails To Unlock

Question 1

Intermittently, for the last two years the shift lock in my 1998 Toyota RAV4 has been sticking.  The occurrence was maybe once every two weeks.  Now it is getting worse.  Before the trouble began I would start the engine, step on the brake and the transmission shifter would move without any trouble.  Once the trouble began I started the engine, pressed the brake pedal and the transmission shift would not move.  When this happened I could turn off the engine and restart, press the brake and the transmission shifter would move to reverse or drive.  More recently, I had to turn the engine on and off several times before the shifter would move.  Now it is to the point where I need to override the shift lock by inserting a key in a slot before the shifter moves.

My RAV only has 36,000 miles and is in great condition.  I have owned it since it was new and I’m not about to get rid of it.  I have taken it to two different repair shops.  Mechanics at both shops have done tests but can’t determine the source of the trouble even though they have been able to duplicate the trouble.  I’ve asked them to start replacing parts, but they are reluctant to do so.  Do you know what is wrong?  B.G., email

Answer 1
It certainly is not time to dump the vehicle.  I hope your mechanic has not suggested this as a resolution to the trouble. 

More than likely tests have found all components have the proper voltage and are working at the time of testing.  What’s puzzling is if the technicians encounter the trouble they should be able to determine which part is failing.  Be this as it may, it is possible a spilled beverage or dirt is gumming up the shifter in the center console.  This is a condition that eludes tests.  Cleaning may cure the condition.

If the shifter and electrical connections are clean in the console the most accessible part in the system is the brake light switch.  This might have an intermittent fault.  Replacing it may be the cure but this is only a guess.

Ask your favorite technician to take a chance on replacing this part because it has a history of failure.

Additionally, in the future when starting the vehicle apply the brakes first and then turn the key to start the engine.  This procedure will activate the shift interlock as soon as the ignition is activated. 

Oil Smells Like Gasoline
Question 2

I have a 1997 Chevrolet Silverado with a 4.3-liter engine and 80,182 miles.  I purchased the vehicle in 1998 from a new car dealer who used it for demonstration purposes.  It had 3,500 miles on the odometer.  Since then the truck has never given me any problems.  It’s in great shape.  I have changed the oil and filter every 3,000 miles and follow the factory schedule for everything else.  It’s almost like new.

The trouble is that the last time I changed the oil it had a gasoline odor.  Since then I have been checking the oil level more frequently.  It seems to be rising and still has the odor of gasoline.  The engine runs fine.  I have no trouble starting it and the gas mileage has not changed.

The engine starts fine, there is no black smoke from the exhaust, it does not misfire or stumble but I’m concerned that gasoline is mixing with the oil.  Is this due to a bad fuel injector?  Will adding fuel injector cleaner solve the trouble?  Is there anything else I should look for?  S.E., email

Answer 2
Normally, a sticky fuel injector causes hard starts and black smoke from the exhaust especially in the morning before the engine and catalytic converter heat up.  Your nose probably is not misleading you.  If the oil smells like gasoline more than likely gasoline intermixed with the oil.  This is reason for concern because gasoline mixed in the oil reduces the oil’s ability to lubricate the engine.  This could lead to engine failure.

Causes for such a condition are dirty or failed fuel injectors.  Testing the injectors is in order.

Additionally, the design of your truck’s engine is somewhat unique.  The fuel pressure regulator and fuel lines are hidden under the intake manifold.  Any of these parts could spring a leak resulting in gasoline mixing with the oil.  Since your engine is running fine, and taking into consideration the vehicle’s age, it is more likely one of these parts is leaking and the fuel injectors are okay.  To determine if a line or pressure regulator is leaking the intake manifold needs removal.  Repair all depends upon what trouble is found under the manifold. 
Transmission Falters When Hot
Question 3
I have a 2002 Volvo S60 turbo with a 2.3-liter engine and 157,000 miles.  I have maintained the car according to the book since it was new.  Recently, the transmission shifts fine for the first few miles but once I have driven about 10 miles it does not shift normally.  When it upshifts to the next gear it takes longer for the next gear to engage.  The transmission disengages first gear and then it seems to go into neutral and then it engages second gear.  The engine revs a little in between shifts and then second gear engages sometimes a little more abruptly than usual.

These conditions are intermittent and do not occur every time I drive the car.  Some days I can drive thirty miles or more without any trouble at all.  On other days after I drive ten or so miles the transmission acts up.

I have taken the car to two different repair shops.  Both shops checked the computer for trouble codes and test drove the car.  No codes were found.  One shop updated computer software.  The other shop flushed the transmission and checked for computer codes and updates.  Both shops experienced the trouble during a test drive.  Neither shop is exactly sure what causes the trouble but one shop suggests replacing a valve body might solve it.  Do you think this makes sense?  N.N., email

Answer 3
Obviously there is no guarantee that replacing the valve body will cure the trouble.  Be this as it may, the valve body has a number of solenoids and valves that direct hydraulic pressure to various parts to shift the transmission.  When a valve is excessively worn or sticks the shift pattern and quality of the shifts can be adversely affected.   Certainly the symptoms you describe might be resolved by replacing the part.  Also, it certainly is much less expensive to replace the valve body than to overhaul or replace the transmission.

Front Brakes Become Excessively Hot
Question 4
After I drive a while the front brakes in my 1998 Mazda 626 seem to get hotter than the rear brakes.  I discovered this when I stopped in the parking lot at work.  I smelled something and found the odor is coming from the front brakes.  I spent the day at work and drove home and encountered the same odor.  I took the car to a repair shop the next morning. 

A mechanic said the brake pads are fine but the rotors look discolored from heat.  He said that the brakes are working fine and the odor probably was due to heavy stop and go traffic.

The next day when I drove to work the front brakes smelled and I thought I saw smoke coming from them.  I called my repair shop and was assured the mechanic did not find any problems.  Despite this the manager said I should bring the car back for another look.

The next morning I drove over the repair shop.  A mechanic checked over the brakes and agreed that the front brakes look as though they have been hot but the wheels were turning normally so the brakes were not dragging which would indicate a problem.  Once I arrived at work the odor at the front brakes returned.  I called my repair shop.  They sent a tow truck to pick up the car.

Two days have passed since the shop picked up the car.  The mechanic can’t find anything wrong other than the brake rotors have a dark color.  Do you have any suggestions?  A.H., email

Answer 4
The fact that the brakes emit an odor, smoke and are discolored is indeed cause for concern.   The technician at your shop needs to drive the car the distance you drive to work under similar conditions.  Once he experiences the odor he likely will agree something is malfunctioning in the brake system.  Right now he may not think there is a problem except that perhaps you have a lead foot and make jack rabbit starts and stops or ride the brakes.  Give him authorization to drive the car the distance you drive to and from work.  He certainly will encounter the symptoms.

A problem such as this can be caused by a fault in the antilock brake pump, a stuck proportioning valve, sticking caliper pistons or slides, a fault in the power brake booster, misadjusted brake pedal push rod, faulty or misadjusted brake light switch, a fault in the brake master cylinder, or condition such as a restricted hose or kinked line. 

There is no doubt your technician has much to examine but he will find the cause of the trouble once he drives the vehicle under conditions similar to your commute.

Height Of Right Front Corner Drops While Driving 
Question 5
After driving eight to ten miles in my 2005 Land Rover Range Rover the front passenger side drops lower that the rest of the car.  I took the vehicle to an import repair shop where a mechanic scanned the computer that controls the suspension.  He found codes that indicated a problem, cleared the system and activated it to see if there were any leaks at the right front strut.  The vehicle was parked all night in the shop but no leaks were found anywhere in the system.  He drove the vehicle 14 miles and the passenger front dropped.  When he returned to the shop he did some tests but could not find any leaks or other problems in the system.  Now he is at a loss as to what is causing the trouble.

Can you help?  R.M., email

Answer 5
Sometimes all the high tech equipment available to a technician just cannot find the cause of a problem.  When this happens sometimes low tech old fashioned methods can rule the day.  Since we know that there is a leak somewhere in the lines or strut at the right front suspension soapy water applied to all the parts might bubble at the site of the leak.  If so, he will know exactly which part has failed.

Since it is rather easy and obvious to find leaks at a line he may find that the strut leaks in an area that can only be seen when it is fully extended.  If the strut has sprung a leak, replacement should put an end to the trouble.

Murphy’s Law Strikes 
Question 6
I replaced the front and rear brake pads and rotors in my 2004 Acura RL.  Before the replacement no warning lights were on in the dash.  After the repair I backed out of my driveway and as I started to drive away the red brake warning light turned on.  The brakes worked fine.  I returned home pulled the wheels and checked all of my work and made sure the fluid level in the master cylinder was proper.  Everything looks fine.  After I checked everything I went for another ride.  This time the yellow ABS light turned on.  The brakes still worked fine.

For many years I have been replacing the brakes on my cars and have never had a problem like this arise.  Do you know what causes the lights to shine?  M.N., email

Answer 6
Sometimes, as diligent as a person can be in repairing a vehicle trouble strikes.  At this point, it is time to take the vehicle to a repair shop to have tests performed on the anti-lock brake system.  It’s possible something has failed but more than likely the system needs resetting.  The trouble probably is not due to an error on your part.   Chalk this up to Murphy’s Law which is anything that can possibly go wrong will go wrong at some time.  It just happened to be your time for something to go wrong.

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.  6/22/2012 ® DR. GIZMO © 1989-2012