No reverse, whining noise

MSPSIMS

MEMBER
2001 GMC YUKON
5.3L
V8
4WD
AUTOMATIC
236,523 MILES

I was driving with no issues. All of a sudden there was this whining noise coming from what I thought was under the hood, but I think it's coming from underneath the truck; the transmission maybe. Anyway, I pulled into a parking lot and tried to reverse. It reversed slowly but I was able to back up and make it home. The whining noise eventually stopped and I made it home, but could not reverse into the driveway. Now it wont reverse at all. Had absolutely no problems prior to this and there is transmission fluid in the vehicle, looks and smell normal. Please help! I am hoping it is just I need to change the filer and fluid and not a rebuild. I'm praying it's not the sun shell. Anyone think they know?

7 Replies

STEVE W.

MECHANIC
13,441 POSTS

Well, as you check the fluid already I'll skip that. Here is a way to tell if it's the sun shell: First you have no reverse that is a bad sign. Take the truck out and use the shifter to put the transmission in low, Start off does it move okay? If yes, shift it up one gear into second, what does it do? If it suddenly starts revving up with the truck slowing down it's not looking good, so now shift to third, if it starts moving again go to drive, if you feel it shift into 4th gear and it starts slipping, the sun shell is the problem. The good news is that if the rest of the truck is in good shape you can have a shop rebuild the unit and install all the good parts to make it better than OEM. Plus being you lost reverse the transmission would need to come out anyway as that section is inside the case. Sorry to be the bearer of bad news.

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Saturday, December 5th, 2020 AT 12:37 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

Good morning,

I would change the fluid and filter. It is worth a shot but I doubt it will resolve this issue.

https://www.2carpros.com/articles/how-to-service-an-automatic-transmission

https://www.2carpros.com/articles/automatic-transmission-problems

Keep me updated with the results.

Roy

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Sunday, December 6th, 2020 AT 7:43 AM

MSPSIMS

MEMBER
3 POSTS

Okay. I have yet to find a trustworthy mechanic or shop. But I may have found one. I'm just waiting for an appointment (thanks Covid-19 ). Anyway my sons and I were able to push the truck backwards to get it out of the driveway to park on the street for easy access for a tow truck but it drove fine in all gears except reverse. It still makes the whining noise and now shakes a little. So, maybe the reverse pump is gone out? Maybe change the oil and filter on the transmission and maybe the reverse pump? I wonder if that will work. How extensive is replacing the rear pump?

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Sunday, December 6th, 2020 AT 12:37 PM

ASEMASTER6371

MECHANIC
52,797 POSTS

There is no rear pump. There is only 1 pump and that is the front pump.

Roy

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Sunday, December 6th, 2020 AT 12:42 PM

STEVE W.

MECHANIC
13,441 POSTS

As Roy says there is only the single pump, if all the forward gears work but no reverse and it is rattling and whining, the likely culprit is still internal to the transmission and I doubt a fluid change would do anything simply because if it was fluid related there would be issues in the forward gears as well. The 4L60-E you have has a few known issues and the sun shell is one it has a few symptoms, if the splines strip it can cause loss of reverse but usually a loss of 2nd and 3rd as well. However if it simply cracks through the shell it will cause a loss of reverse and noise, another is the reverse clutch pack coming apart or the snap ring that retains the reverse input drum has come off. The snap ring usually causes the loss of reverse but no noise or shudder. In all cases I would expect the transmission needs a rebuild.
The attached is what the internals look like on that transmission. The reverse input clutches are part #110 the snap ring is #892 and part #624 is the sun shell.

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