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jbres's avatar
jbres
Explorer
Jan 28, 2014

whining noise on 2007 GMC Sierra 2500HD

I always enjoy coming on here and getting advice on minor bumps I come across along the way..
My current issue is on cold days only, I have a "whine" when first driving my truck until it warms up after about 10 mins. It occurs ONLY when temp is about 32 or less. I start it up, let it warm up for 10 mins or longer, pull out of my driveway and as I approach first stop sign on my street my truck has a SLIGHT "whine" as it downshifts in the lower gears only. I continue to hear it every time I slow down say like coming to stop signs or lights. The whine is almost going synchronized with the downshift of the transmission. The transmission still performs 100% perfect even with the noise. No rough shifting or any codes or anything.

Once the truck is warmed up, absolutely no "whine". Also, if it gets parked in my work garage overnight where its warm, you wont hear a thing.
Truck is a 2007 GMC Sierra 2500HD 2wd with the big 4L80e transmission. Only has 68,000 miles on it, and I bought it in fall. Transmission was serviced, filter changed and fluid change in fall.

I took it to my very reputable and trusty transmission repair shop and the first time he left it in garage overnight and said didn't hear a thing test driving it the following morning.
The next day he left it parked outside overnight and test drove in the morning and said he heard the SLIGHT whine as it downshifted coming to the first few lights. The noise went away on him and he brought it in and looked it over.
He calls me today and said he highly recommends not to even dig into transmission because he said there isn't enough concern to take it apart etc etc.. He said he could spend the time and money taking it apart putting it on the table and find nothing wrong with it then I will really be mad. He says to ignore it.
He says he has to much doubt in his mind its even the transmission. Said miles are too low and way to well kept to think its the trans making the noise.

Any ideas on what the noise could be?
Or anyone ever have a similar sound in the Chev Gm transmission?
I pulled off all 4 brakes and they look perfect. Truck is in pristine condition, was meticously maintained by previous owner.
I was thinking about taking it to the local "stealership", but not sure that is even a good idea