Allroad 4.2 engine mounts?

[maulroad]

I'm new to Audi, Audizine and the Allroad. I bought a 2004 Allroad 4.2 that had a known torque converter failure. The car is back in one piece after TC rebuild, main seal, oil pan gasket, tranny filter service, spark plugs, coolant flush, expansion tank, aux radiator replacement, air/cabin filters, [wrench] etc. I got a clean read from vagcom except for the p1577 motor mount failure for the right mount. The car shakes from what feels like the drivetrain. I can't really tell a difference at idle versus motion or at any particular rpm. On the test drive, I also noticed more engine/fan/belt noise inside the cabin than before. Shifting seems smooth and engine power seems to be normal. The engine seems to be in the correct location and the snub mount appears free from the carrier.

Prior to the tear down, I scanned the car with a generic OBD2. The only code it pulled was for the torque converter. Currently, the CEL is off but the VCDS finds the engine mount code. I guess the mount(s) could have been bad before - but I didn't have the same vibrations. I crawled under the car while it was running to inspect the mounts. I can see the transmission mounts moving, but both (left and right) engine mounts are static. I assume that's a sign that the engine mounts are not functioning correctly; however, when I search for threads on the subject, motor mounts seem to deteriorate over time rather than abruptly fail.

New mounts are on the way and I'll dive back into it over the weekend.

Does anyone have suggestions on other things to check before or while I'm at it? Or is this an obvious case of bad mounts?

[crono35]

did you do the labor yourself? If someone else did it, it's possible that the mount was damaged during installation. Not sure how the 4.2 mounts work but on my old b5 a4 it can be very easy to miss an engine mount hole and destroy even a new mount.

[maulroad]

I did the labor with the help of a mechanic (not Audi specialist). We did a little jiggling to get things in place but weren't too ham-fisted about it. I guess we could have snagged them.

[maulroad]

New motor mounts are in. The car isn't throwing any codes. Unfortunately, it's still shaking.

Now the shake is worst at idle and about 2k rpm. Seems to smooth at higher rpms but it's never gone.

[S4NOWRS4L8ER]

Is it possible the tc is not balanced or not evenly torqued down? Don't know much about auto trans...


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[maulroad]

A few people suggested tc balance as the cause of the vibration. I called 517 Trans (who rebuilt the tc) and Sam didn't think my symptoms were consistent with bad tc balance. Paraphrasing, he expected the vibration to get worse with more rpm if the tc was the problem and suggested I check my crank pulley. I had it off for the main seal replacement and may have re-installed incorrectly which could be throwing off the balance.

This sounds good to me since pulling the carrier is easier than the transmission.

[maulroad]

I have some updates!!

(1) Sam from 517 nailed it with his over-the-phone diagnostic. I put my crank pulley on wrong (180 degrees off).

(2) 4.2 Allroad crank pulleys should have dowel-sleeves installed on one of the bolt holes. This aligns with a counter-sunk hole in the crankshaft. This is also why Alldata says the pulley will only go on one way.

(3) My sleeve is missing (either due to my own sloppiness or a prior mechanic). I'm certain that it is removable because (a) it's gone and (b) JHM's lightweight pulley installation notes say: "Also note that one bolt hole has a dowel in the stock pulley and must be removed and inserted into the JHM pulley."

(4) Audi does NOT have a part number for the dowel-sleeve for the 4.2 Allroad

(5) Awesome parts guy at the dealer was able to look up ALL alignment sleeves and narrow it down to one possible part (11.125mm x 6.5mm). This is the sleeve used in the R8...so my car will be pretty fast after this mod.

The sad wagon has been in the garage since Thanksgiving. With a little luck, she'll be on the road by Sunday!