Not Duramax, but can anyone ID this noise?

[Cougar281]

My wife blew the turbo (broke the shaft) in her TDI Jetta two weeks ago this coming Saturday. I've spent the last week and a half getting it apart and back together (mostly about 1hr per day of work on it).

Got it all together after replacing the turbo (Boy was that fun - especially the stupid DPF.....) and there's a new noise that I can't ID. It seems to only be there at idle. If I increase the engine speed by just 100 RPM, it seems to be gone. It also is gone once the engine is at operating temp. Drive tests are normal - no odd noises, plenty of power, etc.

Here is the engine running cold:


Here is the engine running at temp - sounds normal:


It doesn't sound like a bottom end issue, and while the failed turbo puked oil into both the intake and exhaust (probably 1qt drained out of the intake and it smoked like crazy burning the oil out of the DPF), it didn't get run dry. It wasn't on the dipstick post failure, but it only took 1/2 qt/L to get it showing on the dipstick and another L put it well in the safe range. At times, it seems almost as if it's coming from the DSG bell housing, but it could also be exhaust... but nothing jumps out at me.

Anyone have any ideas?

 

[02greysixer]

I can't see or hear the videos but maybe something broke loose in the dpf or doc. I've seen them get hot enough to break apart on bigger vehicles after turbo or injector failure

Sent from my SAMSUNG-SM-G870A using Tapatalk

 

[DAVe3283]

Yeah, something loose would make sense. That is a strange noise for sure. I could easily believe part of the DPF mesh broke loose and vibrates when cold, but once warm, it expands and snugs up.

You might pick up a cheap mechanics stethoscope and poke around to narrow down the location of the noise.

 

[Cougar281]

I'll poke around some more this afternoon... The only reason I somewhat doubt it's the DPF (and I REALLY hope it isn't) is this was present from first key-on post repair, so if it had cracked, it almost certainly would have had to have done so pre-teardown. There is no way the DPF could have gotten hot enough in the first 60 seconds of runtime. While I had the DPF out, I shook it best I could and I didn't hear anything rattling. Maybe that doesn't mean anything though :dontknow:

 

[Cougar281]

Well, after getting a mechanics stethoscope and poking around, the noise is most pronounced when touching the bottom of the DSG transmission. It's faintly detectable on the engine block, but very noticeable on the transmission. So it seems it's related to the transmission, from what I gather, probably the lovely dual mass flywheel going bad and almost certainly has been going bad for a bit, it's just getting noticed now.

 

[subman1980]

I think you found the source, sounds just like videos on you tube of a dual mass flywheel failure. I hate those DSG's.

 

[Cougar281]

Can't say I hate the DSG - the trans itself is decent tech. The DMF that's in front of it (and in front of VW's manuals) is arguably a pile of junk tho. I replaced a DMF on an 05 Jetta with a manual trans a while back and boy was that fun. I anticipate this will be even more fun since the DSG is heavier