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Turbo spool-down noise?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=78533		 Page 1 of 1
Author:  arasb [ Mon Mar 10, 2014 12:30 am ]
Post subject:  Turbo spool-down noise?
So I'm trying out a dry flow filter (thanks dthdcrd). Excuse the cardboard, it's just for measurement :-)r

Image

As expected, the turbo and air flow are louder, but when I shut the engine off, I hear this sound as its spooling down:

http://youtu.be/bL2BmYvFW7U

Sounds a little more friction-like than I would expect. When I recently had my head gasket, TB, WP replaced, and ARPs put in, the guy mentioned that the turbo looked great and was most likely replaced by the previous owner. Bought it with ~30k and now I'm at 94k. I've always heard air rushing noise when shutting the engine off. Just seems different and maybe shorter than I remember.

I see no oil leaks and oil level is normal.

Is this a normal sound?

Thanks,
Aras
Author:  papaindigo [ Mon Mar 10, 2014 8:11 am ]
Post subject:  Re: Turbo spool-down noise?
Honestly do not know but is does sound a bit raspy. I'd suggest taking the intake hose off at the turbo and checking the fan for play. Very slight fore/aft is ok as is barely perceptable side to side. If that's the case just drive it.
Author:  arasb [ Mon Mar 10, 2014 9:38 am ]
Post subject:  Re: Turbo spool-down noise?
Thanks, I'll check for that tonight.
Cheers,
Aras
Author:  arasb [ Mon Mar 10, 2014 11:53 pm ]
Post subject:  Re: Turbo spool-down noise?
Took off the turbo inlet hose and found a crack in the hose.

Inspected the turbo fan and found some play side to side, but not really any front to back (axial). See video:
http://youtu.be/AnYNBs-FmYs

Replaced the hose. I'm wondering if the sound I'm hearing is due to the FCV closing at shutdown, causing back pressure that forces the turbine to slow down quicker while making some air noises. I'll see if this changes after I get weeks101 intake elbow.

Thanks,
Aras
Author:  papaindigo [ Tue Mar 11, 2014 10:05 am ]
Post subject:  Re: Turbo spool-down noise?
Inlet hose crack is fairly common but in my opinion that's way too much side to side play to expect long turbo life. Let's see what other's post although you may want to email Keith at GDE for his opinion. With that amount of play I would not be surprised if the sound is the tips of the blades scraping on the housing as the turbo spools down.
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