I have a 1988 Oldsmobile Delta 88 110k miles with the 440-T4 transmission, when pulling away from a stop sign the car revs up like it was put into neutral and when the RPMs come back down it will go with no problems. Sometimes if I give the car gas between downshifting from 2nd gear to 1st it will rev up for a second or two and then move with no problems. Sometimes I will drive the car and you can step on it hard with no slipping whatsoever and it shifts fine. This problem has happened both at operating temp and cold. Fluid is brand new Mobil 1 Dexron 3.

Any ideas?

Matt

Did the problem start before the new fluid or after?

After...Gulp

Actually i'm wrong to say that. It dropped into neutral at a stop sign ONE time right before I changed the fluid a few months ago.
I used this stuff here,

https://www.summitracing.com/parts/mob-123130?rrec=true

Matt

Uh oh, I've seen this happen before. New fluid makes the older ones slip sometimes.

Like dropped into neutral or it did the slipping thing like in your original post?

Dexron III not VI so that'* good for this transmission, good manufacturer.

My guess at this point: It'* starting to slip in first and/or the pump isn't keeping pressure up. It might be a bad vacuum modulator stuck at high-vacuum (therefore lowering line pressure), but that would be a huge stretch and would be secondary to an internal issue.


Did you change the filter?

This is how everything happened, I bought the car in June of last year with 98k miles on it. This is actually my daily driver and the only car I own... I noticed the transmission fluid was darker colored but still had a hint of red to it. I did a pan drop and changed out 6.5 quarts with Dexron VI along with a new filter. I drove around on that fluid for a little over a year with no problems until Sep of this year when I noticed that the car reved up at a stop sign in drive, I waited for the RPMs to come back down and the car started to move and it never did that again for a few weeks. At this time I bought 12 quarts of Mobil 1 Dexron 3 and flushed 4 quarts of the CURRENT Dexron VI fluid out the cooler lines and replaced it with the Dexron 3 being careful not to run the transmission dry. I drove around for a few weeks and did ANOTHER pan drop and replaced the rest of the fluid with the Dexron 3. So all of the Dexron Vi has been cleaned out of the system and replaced with the proper fluid. All was well until mid October when the stop sign or red light issue happened again. upon takeoff the car will rev like its in neutral, no shuttering or clunking just a rev with no movement until it comes back down to idle and moves on its own. Later that week I was pulling into the driveway after the car had shifted from second into first doing about 20 MPH I hit the gas and nothing happened so I manually shifted from Drive to Neutral and back to drive really fast and the car took off fine. These issues happen off and on hot or cold and i'm not yet sure as to why. I pulled the vacuum hose off the STOCK modulator and no fluid came out. I inspected the little vacuum hose for cracks and its in good shape. I unhooked the battery to reset the computer with no change.

Not sure where to go from here,

Thanks,

Matt

I shouldn't say dropped into neutral, It slipped like it was in neutral.

Hmmmmm . . . maybe it'* a bad shift solenoid or one or more of them has gotten plugged or some junk is floating around behind it. If it'* slipping it would usually be all the time, but junk in a solenoid or a bad solenoid can be intermittent.

I woke up this morning to a flat tire and about a quart of transmission fluid sitting on the garage floor I looked underneath to find a leaking axle seal.

This car just doesn't want to cooperate!

Wow, that'* unfortunate timing!