While driving after reaching thirty five mph the RPMs go way up

BYRON HAKEEM MCNAIR

MEMBER
2003 GMC ENVOY
4.2L
V6
2WD
AUTOMATIC
200,000 MILES

My car idles good when I crank it up. I recently added transmission fluid because it was low on transmission fluid. When I'm driving it drives smooth until I reach about 35 mph then my rpm's shoot up to between 4-5 rpm's. That's way too much rpm's and i'm barely pressing the gas. What do you think could be the problem?

1 Reply

JOETECHPRO

MECHANIC
705 POSTS

Hey BYRON HAKEEM MCNAIR,

It sounds like your transmission is slipping.

For you to have to top up the transmission fluid it is highly likely you have a leak.

Please ensure you are checking the transmission oil as per your owners manual whilst the engine is at operating temperature with the engine running.

Also that you have topped up with the correct transmission fluid.

If the transmission was running with a low fluid level for a period of time you could have caused some internal transmission damage.

Once you have ensured you have the right oil level if the fault still remains you can try replacing the transmission oil filter apart from that you will need to scan for transmission codes and see what you have.

I have found a TSB (technical service bulletin) that seems to describe your issue.

If you can inspect your transmission for leaks, attach a picture if you find any.
The TSB describes an issue with the output oil seal to the left front driveshaft leaking.

TSB attached.

Hope this helps.

Regards, Joe

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