AudiQC

Hello Fellows,
My allroad 2003 tranny, with 350,000 km (216 kmiles) is slipping in 1st gear on medium throttle. As soon as it goes in 2nd, i can push it to the floor and it goes......
I do also (sometimes) experience some bizare reactions changing rapidely from front to reverse gear...Is the tranny gone or just the TC ? My mechanic told me not to touch it (oil change) or rebuilt it. What you guys think about my problem?
Thanks in advance....

G0to60

First. Do you have anything plugged into the OBD port like a scan gauge, gps, etc? I have found that these devices can sometimes send so many requests to the ECU for data that it causes weird problems. For me the trans would downshift then upshift very quickly. It felt like a big clunk when it did this. I had a bluetooth plug in for the Torque app in the port at the time and unplugging that fixed the issue.

If that's not the case then you may have a couple of issues. The reason you mechanic won't do an oil change is because he is scared that the trans will fail shortly after. The fact is that if the trans fails after an oil change the trans was on it's way out any way. I changed the fluid on mine at around 175k miles with no issues. I would change the fluid (~$100 in parts) with the hope that it will fix the problem but with the expectation that there are deeper problems.

I'm not sure why your mechanic wouldn't recommend a rebuild unless he doesn't have the skills to do it. That is usually the fix when the trans shows problems like yours. It's usually either the torque converter or the reverse drum that is the problem. Talk with a transmission shop that is familiar with these transmissions (these were also in BMW's of the same era).

The other option, if the trans turns out to be bad, is to convert to a manual transmission. This is usually about the same price as an automatic trans rebuild.

AudiQC

I don't have anything plug in OBD port or the like. I have probably express myself a wrong way. My mechanic told me "no oil change" but a rebuild is the "solution". But after all I may try the "oil change" and see the results

crono35

bad TC is usually evident in all gears, and should throw a check engine light. I'd hook it up to a vag com and scan for codes before anything else.

amiram

Check trans' fluid level (37 C \ 100 F )

AudiQC

I finaly decided to go my way !! I had the oil changed. It's only few days and i can feel the improvement. The oil was so dark and full of black "particules" ...I couldn't believe it when my mechanic showed me the old filter and some of the oil that was "extracted" from the tranny.
Yet i am very happy with the results......
Happy New Year to all allroaders and drive safely....but "sportly"!!!

jjrichar

I would suggest doing another oil change after you have driven a bit. You will only have been able to remove about 60% of the oil that's in the transmission due to a lot of it remaining in the torque converter.

The problem is the transmission clutch characteristics are hugely determined by the quality of oil. At 350,000 km, your oil was beyond its use by date about 250,000 km ago. You need to get out as much of the old oil as possible. The only way to do this easily is to do multiple oil changes after the previous good oil has been mixed. For the consequent changes, you don't have to drop the pan and filter. Just drain and refill. Eventually you will have a high proportion of good oil in the TX.

Of note, the filter is more like a sieve than a filter. It's just for coarse particles, which there should be very few. It's very different to an engine oil filter, and is pretty much impossible to clog. The smaller particles are suspended in the oil or collect on the magnets on the pan. The oil molecules break down over time, and hence the problems. This is why just draining the oil after you have done an initial filter change is all that is necessary.

We bought our 4.2 allroad when it was 117,000km old. Soon after buying it developed a shuddering on acceleration. I did transmission oil changes every 10,000km for about 5 changes, and now just drain and refill every 20,000km. When I drain the oil now it is the colour of new oil, so I'm considering draining at a longer interval. The car has now over 200,000km, and interestingly, the transmission performance, after an initial improvement after the first oil change, seemed to get better after each additional oil change.

AudiQC

Thanks jjrichar! I must say that i had made an oil change 2,5 year ago at around 250 000 km, but i am not sure if my mechanic (at that time not the same as now) did it properly. And i remember that i had the "converter" changed on waranty by the dealer at around 100 000 km. The "dealer" told me that they also changed the oil.
I must say (if i haven't aready mentionned) that i have towed a camping trailer (of aroud 4000 lb) in the last few year in very tough conditions (hot weather and hilly road).
But i love your idea of doing some more oil changes to improve oil quality overall.
Thanks again for the suggestion.