ars

Hi,

I've faced some transmission issues on my -99 S8 recently. Been searching the forums for hours, but couldn't find any posts on exactly similar issues.
It had a rebuild done 30k km ago, and the filter and fluid change 10k km ago by the previous owner.

It works fine cold, but when it warms up, especially engaging reverse is delayed/clunky, and feels like it engages a little first, then thumps in properly. Also braking down to traffic lights, but accelerating before coming to a stop often clunks quite nasty.

Would this be caused by the torque converter, and would doing this help? https://www.audiworld.com/forums/sho...php?p=15613320

dreamhope

better than if it doesn't work cold. guess it could be vacuum related.

twentysevenlitres

Have your fluid level checked.
Get it done by someone who knows how to check it properly too.

ars

Ok,

Checked fault codes, nothing there.

Drained the fluid and dropped the pan just to see if the fuild, filter and the magnets seem fine. Started with running through gears, and opened the fill plug. Ended up spraying a lot of fluid all over myself and the floor. The transmission was warm since I had just driven to the garage, which explains the overflow, but there was a lot of it, so could have been just that.

Continued with draining, fluid was quite allright, filter and magnets covered only with some minor goo. So nothing special there which was quite expected with only 10k km since the previous fluid and filter change done by the previous owner.

Next morning proceeded with putting it back together with a new filter and filling with new fluid as instructed on audipages.

Had a test drive last night. Oddly enough I couldn't replicate the laggy reverse engaging, but engaging D and gear changes are still sometimes a bit clunky. Also noticed a completely new problem: During a maximum acceleration felt slipping on the high revs accompanied with a whizzing sound. Testing was a bit tricky due to temp dropping below freezing making parts of the road slippery.


TL/DR - Laggy reverse engaging could have been caused by invalid trans fluid fill, but came across a new problem with slipping clutch. Need more investigation.

tozoM8

I would cut off 10mm of the filter pickup pipe. it gets too close to the bottom of the pan and causin slipping. If your pan has a slightest dent on it the gap is only 2-3mm. I've seen this way too many times.

ars

This was my first quess too, since just before the problems occured my wife's sister drove it and had it scratch the bottom when going over a speedbump. However, the pan doesn't show any damage to it whatsoever, and is rather well protected by the two strut bars (which are obviously scrathed), which had me rule this possibility. I'll lift it up anyway to double check.

Also, after driving around the town for some time yesterday, the lag and thump problem with reverse is definitely still there, and slowing down to traffic lights and moving on just when downshift happens causes the gear to engage with a bang.

dreamhope

I still think you could have the MAF sensor and vacuum leaks checked. Common problem as well.

The filter is unlikely to be the cause of your problem because the transmission could theoretically work perfectly without a filter (until it breaks down). An overfilled transmission could have your problem, but as per your description you have have the fill plug opened after prolonged operation - now it's almost certain your transmission fluid level is low. (There's one correct temperature at which the transmission fluid level could be checked, and this temperature is not that after driving 10+ miles to the shop.) It's also impossible for all your clutches and gears to fail at the same time, so most likely it's something peripheral.

I had a little rough shifting when warm, not very harsh. It was only a broken hose.

tozoM8

Have you ever seen a 5HP24 filter? And no, it won't work without the filter.

ars

I suppose faulty MAF would give some fault codes in VCDS? Could still clean it up though. Will need to run through vacuum hoses and check them. Had plenty of vacuum problems on my previous S3.

As instructed in audipgaes, I let it cool overnight, and went through the fill operation properly.

Hope that's it.

dreamhope

OK, the ZF filters are filters in casings, but if you take the filter core out and put it back the car should still work. That said, I do understand that if the filter tube is blocked due to lack of clearance fluid can't be drawn.