Marti

This forum is littered with auto shift problems, please forgive me for asking more questions - I did search, but did not find the answers

First, my problem.
The car is a 89 S4, the box seems to shift fine around town, but when hot and shifting up under hard load through 3rd and 4th gears it 'stumbles' between shifts. 'Stumbles' means it stops accelerating slightly as if you backed off the accelerator slightly.

Another problem is when the box is hot and shifting down to 1st when slowing down (not stopped) it will not always select 1st gear cleanly, the engine will rev slightly before it snatches 1st. (I think this might be governor pressure?) When the box is cold it is fine.

Also when the box is hot it will not reverse smoothly, it will hop or jerk at low speed. When the box is cold it reverses smoothly.

What I must also add is that these issues were more acute prior to me removing the ATF pan, removing the valve body, cleaning it, replacing the filter, flushing the system and Converter.

The reason I did all this was when I bought the car the car had some work on it due to a failed radiator which had contaminated the fluid. The car was handed into a shop who replaced the valve assembly and changed fluid.

The previous owner did nothing more but sold the car as it had shift problems, told me it just needed more flushing.

When I removed the valve assembly it was quite dirty (although this was a replacement) and the converter fluid was still contaminated. I actually flushed it 3 times to make sure it was totally clean.

I think it might be the governor?
Anyone have any suggestions?

Marti

I wanted to follow up on my original request for help in case this benefits any other owners with a similar problem.

The gearbox is now working fine, I believe the problem to be a hang over of the contaminated fluid in both the box and converter. It needed flushing 5 times before the problem disappeared.

It now selects 1st gear without issue and does not 'hop' when reversing even when fully warmed up.

linderpat

Thanks for the follow up. These transmissions are very sensitive to fluid levels and contamination. Always best to do what you did first with those symptoms, before jumping into an expensive rebuild.

WallyP

Congratulations on being persistent enough to solve the problem, and thanks for the follow-up, even though no one offered any help!

M. Requin

Followups like this are real contributions. Thanks.

Mrmerlin

I would venture a guess that the water contamination was boiling once the system got hot thus the strange operation.
Glad you got the trans working

FredR

Quite unusual that you should have posted like this and not a single response- most unusual. Very glad to note that you got a result and thanks for updating. Do not hesitate to send a "wakey wakey" follow up if you do not receive a response within a day or so of posting.

Did you solve this problem recently or just after you originally posted?

Rgds

Fred