Minimoke8394

Hey all,
First of all, thanks in advance for what will be a bit of an essay, but please read on as I'd love to get the opinions of some more seasoned A8 owners who might have done this job.

Right. My 4.2 PF A8 has done 103k, and had a tranny rebuild at 70k. So I thought I'd give the transmission a service in the sense of a filter and fluid change. Preventative maintenance and all that. Dropped the old oil, changed the filter, bolted the sump back on, filled it up until it flowed out of the fill hole, then started the car.

It sucked a fair bit away, so I filled it up until it overflowed. I then went through all of the gears and kept the box at a slight overflow as often as I could. I must stress this took a long time as the pump I was using was very slow. The fluid was hot. The car was also slightly higher at the front. I popped the filler plug back in and turned the car off. I was pretty sure I put in about what came out.

On the initial test drive something was obviously wrong. A noise that is best described as pump cavitation between changing, delayed changing, but apart from that the car felt fine. I took it back to my workshop, got the car a lot more level, and managed to get more fluid in it. Took it out again, instant improvement. Goes through the gears lovely. BUT. At higher revs there was the pump cavitation again if you booted it. Sigh....

Got it back to the workshop AGAIN, managed to get slightly more fluid in. This improved it again. The noise between shifts was gone, but if you were to use the kick down and let the revs wind right down you would hear it again. Only at those revs the pump cavitation was at a much higher pitch, and only really noticeable when you came off the throttle and the revs dropped fast. Almost sounds like straight cut gear whine.

Now. I understand that the way I filled the car up was far less than ideal, and that it's important that the temperature of the ATF doesn't go above 40c when filling the gearbox/sump. I believe this is because of an oil cooler valve opening? The whole episode has been pretty distressing and the only thing I can think of trying is dropping the fluid overnight and refilling it the next day, with a better pump. And by monitoring the box temp via VAGCOM if I can borrow it from a friend.

My question, and the reason for this (very) long essay, is has anyone had a similar issue before? Does it sound like I've caused any damage? The 'how to' I followed was from Audipages.com, and it simply states that "If you hear any noises, check the level again." I can only assume that the level isn't quite right? I must have only got another 200ml in the box the last time I filled it, and it made a definite improvement. Does my plan for remedying the issue make sense?

Thanks in advance for any help any of you can give on my problem. At the moment I feel like I've spent quite a bit of money on service parts, only to make my car worse....Frustrating eh.

Regards,
Chris.

C.O.R.E.inMinnesota

My main concern would be if there is an O-ring between the filter and the sump, perhaps it is not sealing. This will allow proper transmission function while the level is above that oring. Then during higher rpms the sump level will be less.
And this may seem obvious but ensure that ATF is Audi spec.
Was the filter you removed the same type as the one you installed? I.e. paper versus screen type?

twentysevenlitres

There has been a lot of trouble with filter oil pick up tubes on aftermarket filters being too long.
This will result in oil starvation issues due to far too little clearance between the pick up and the bottom of the sump.

Unfortunately the only way to check it is to pull it back out and sit it on a nice flat bench and compare it to the old one!

Minimoke8394

Thanks for the replies guys. I got everything from my dealer, so the fluid, filter, o ring etc is all from them. The filter looked the same in terms of the material inside yes. When I fitted the new filter I vaguely remember making sure it was sealing, and I couldn't move it around in the pipe if that makes sense. But when I looked at the old filter, the top pipe did look different to the new filter....This is once I'd had issues though so I don't know if I was just looking for a reason. About 6 of the 25 bolts were really rounded so getting them out and back in was loads of fun....What you say about the higher revs needing more pressure does make sense though yes. Would you guys suggest doing what I plan on doing? The fact that adding more fluid improved the fault massively makes me want to go through the filling procedure one more time. And if that doesn't work, then off with the sump I guess....Joy!

Thanks.

silverd2

Following the correct filling procedure IS critical to success. Car DEAD-level whatever it takes...start stone cold, fill, start, keep filling till overflow and no hotter than good bath water, plug it, shut it off.

No noise is preferred, but high pitched "whirring" from the trans pump is not totally uncommon in older trans's without eminent failure...mine has had a quiet (louder when cold) whir for at least 60K miles (before and after atf/filter change) and operates perfectly at over 130K miles.

Unless you want to spend a lotta $$, if the trans is operating properly, A little pump noise is not necessarily sudden impending doom.

Minimoke8394

Thanks for the reply mate. I don't think it's actually doing any damage, but obviously it's nice to give the car a bit of stick every now and again (I'd have bought a 2.8 otherwise) and the straight cut noise when the revs drop makes me want to not do it. I'll drop the fluid overnight and go through the procedure properly. If it comes out looking like a West Coast Customs paint job I'll know I've done some damage....All I've changed is the filter, so it has to be the fluid level that's wrong....Hopefully.

Cheers for the replies guys.

Chris.

pocketchange

Interesting OP,

Was curious what your fluid looked like after the second draining?

I'm partial to Allison Synthetic spec ATF since I've had good luck with it in my A8
and everything else with an automatic in my stable. pc

Minimoke8394

Hey,
I'm away at the moment so haven't got around to it yet. I'm thinking the same thing though. I've done less than 100 miles on this fluid so I'm hoping it comes out looking brand new. When I parked it up before going on holiday it didn't go straight into reverse, took a split second and then went back. I was in a hurry though so hit the throttle quite hard. I know that is a telltale sign of a filter past its best, so I'm hoping that it's just the fluid level doing that. I shall be sure to update this thread with my findings.

Ta,
Chris.

Minimoke8394

Hey,
I'm away at the moment so haven't got around to it yet. I'm thinking the same thing though. I've done less than 100 miles on this fluid so I'm hoping it comes out looking brand new. When I parked it up before going on holiday it didn't go straight into reverse, took a split second and then went back. I was in a hurry though so hit the throttle quite hard. I know that is a telltale sign of a filter past its best, so I'm hoping that it's just the fluid level doing that. I shall be sure to update this thread with my findings.

Ta,
Chris.

Minimoke8394

Well I just went for a standard top up, but did let a bit of fluid out for inspection. It was as clean as the new stuff, didn't smell burnt etc. I managed to get a bit more fluid in there, but it made no difference. I am now going to drop the sump and compare the filters. Wish I never bothered with this job....Will update here when I've made some progress.

Chris.