Transmission noise, what is it?

spunkymonky · Post by **spunkymonky** » 21 Feb 2020, 10:16

I'm going nutz trying to isolate a noise that has suddenly appeared on my wife's 2000 S80 T6. It sound like a knocking and/or rubbing noise, moderately loud. This noise follows engine rpm and is there in neutral or park and when driving, however when you shift into drive or reverse at idle the noise gets noticeably quieter almost non existent. Once you start moving and accelerate the noise again follows engine rpm, however if you take your foot off the gas completely and coast, the noise disappears totally. I have put a stethoscope on the car and have been unable to locate the source although it is on the drivers side and sounds like it's coming from the transmission. I have hooked the car up to VIDA and there are no DTC's. Eliminated turbos as source. The only things I can think of is the transmission oil pump but I've always heard that's more of a whine and I would expect drive ability issues.It has been driven about 2000kms now while making this noise and speeds up to 210km/h with no other symptoms.

any guesses? Video is in neutral idling, shifting into drive when noise disappears and then accelerating back in neutral.

Post by **RickHaleParker** » 21 Feb 2020, 12:53

spunkymonky wrote: ↑21 Feb 2020, 10:16 I have put a stethoscope on the car and have been unable to locate the source

In this case a Ear Trumpet may work better then a Stethoscope.

spunkymonky · Post by **spunkymonky** » 22 Feb 2020, 11:59

Thanks, I'll give that a shot next. I was hoping someone would have insight on why the noise would disappear in drive/reverse.

Post by **SuperHerman** » 23 Feb 2020, 23:15

Sounds like the flex plate - maybe something got stuck up there or it is failing. I am not sure if that car has a metal space plate near the bottom, maybe this is loose (could be a design on another car). I suppose you can crawl under there and try tightening the bolts that you can see.

Other possibility is the torque converter bolts are backing out.

Check all your serpentine belt bearings, a/c clutch, alternator and power steering pump. It may not be the transmission.

spunkymonky · Post by **spunkymonky** » 24 Feb 2020, 22:03

The only problem with flex plate theory or TC bolt is that the noise shouldn't stop when put into drive or reverse or coasting in my opinion . It should stay consistent no matter what as long as the engine is turning don't you think?

It's also definitely not on the belt side of the engine or at the turbos. Very pronounced on the drivers side and unfortunately there are no rotating external parts on that side.

Post by **RickHaleParker** » 24 Feb 2020, 23:02

It is rare but starters have been known to knock. You might get your stethoscope on the starter and check the mounting bolts.

spunkymonky · Post by **spunkymonky** » 28 Feb 2020, 08:42

I sent an email to David Norris from Triple Edge Performance who specializes in these transmissions and his guess based on all the details was the Drive Sprocket Bearing. So I assume there will be no drive ability issues until the bearing completely blows up. Looks like a removal and rebuild.Oh joy.