CAR DOCTOR Q&A: Time Is The Best Diagnostic Tool

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This week, AAA Car Doctor John Paul follows the Bert Lance School of Auto Maintenance regarding a 2001 Pontiac Bonneville with a whistle, suggesting “If it ain’t broke, don’t fix it.”

Q. I have a 2001 Pontiac Bonneville with a 3.8 liter V6 and four speed automatic transmission. The problem is the car has a high pitch whistling/whining noise that’s loudest when I start off and louder now with the colder weather. The noise stays with you almost all the time going from loud to softer at will. I have had both the alternator and air conditioner compressor changed. I’m now being told it’s the transmission. I went to a have the transmission checked but, one transmission guy said the transmission wouldn’t make that kind of noise, one said it could. Neither mechanic heard the noise and only was going by my description of the problem. Any thoughts on what this could be?

2001 pontiac bonnevilleA. The first thing is to determine if the noise is a component driven by the engine. This can usually be accomplished to removing the various drive belts to see if the noise disappears. This should be done with caution since one of the belts drives the water pump and you don’t want the car to overheat. These engines were very fussy about drive belt alignment. If one of the pulleys is out of alignment even by a bit the belts will make noise. Once you have determined the engine is not the problem. then you would want to eliminate any rotational noises causes by wheel bearings and brake components. Once you have eliminated all of these possibilities the transmission is about all that is left. Considering the age of the car I think I would drive it until the noise becomes more apparent or effect the operation of the transmission. This may be a case of time being the best diagnostic tool.