8 replies to this topic

[JimmyHoffa]

I just took my turbo center section off today to fix a leak from my drain and I noticed some damage/erosion on the turbine wheel tips. I have a feeling it's from elevated EGTs. My car has also not been building boost as fast, or generally feeling as quick as it once was (probably partially due to the turbine damage). I'm thinking it may have something to do with my timing being retarded which usually raises EGTs. I've got a DM billet crank pulley and I think my knock sensors may be picking up excess bottom end noise that would usually be damped out by the stock harmonic damper, and since the ECU thinks it's knocking, it's pulling timing, making my car slower and cooking my turbine wheel.

Has anyone else had issues like this, or has any advice? I might try swapping out my knock sensors since I have a spare set. Is there any way to test them to see if they're in spec other than putting a scope on them?

[7MX63]

Does the center section have a lot of play? Not side to side, but front to back? This will also cause the turbine wheel to get f'ed.

It'll start to touch the housing and as it breaks or rubs away more boost leaks around the wheel, and the problem gets worse.

[JimmyHoffa]

Nope not much in/out play at all, and what I would call normal side to side shaft play (a few thou, maybe .010" max) on the compressor side, even less on the turbine side. It aslo doesn't look like contact, it almost looks like it's being sandblasted and eroding away. It's not looking great but it's also not terrible yet. I'll definitely need to replace the turbo before too long, but hopefully it'll make it through this season if I fix the root cause of the problem.

[Jason]

ATI fluidamper

or put the stock crank pulley back on and test your theory. if your logic is sound (and it sounds like it is) then the fluidamper will be the logical choice.

[Kyle]

Is there any way for you to tap in and monitor knock sensor voltage in real time? I was gonna say run it through the revs and record, then switch pullies and repeat. Only way I could think of definitively ruling this true or false

[Mo]

In my Peterbilt, I fried a turbine on the exhaust side from high EGT's caused by a back up in this newish system called a DPF which is like a oversized catlytic converter with a fuel injector designed to burn out all the trapped unburned particulates aka soot. The exhaust out the tip reaches 1300 degrees if the system is functioning correctly. Based on my experience, I'd say EGT is your cause but then again your engine doesn't rely on 30+psi of boost lol.

[JimmyHoffa]

AFAIK diesel exhaust is usually lower temp, lower energy than gasoline exhaust , part of why holsets respond so well on gas engines less than half the displacement they were designed for. I don't know much about the new diesel systems tho.

[JimmyHoffa]

I just put on the stock crank pulley, unplugged the battery for a bit to reset the ECU and then took it for a drive. The turbo seems to spool a little bit faster and definitely idles a lot lower than before (I have no working tach so I'm not sure exactly what rpm). I'm probably going to pick up an EGT gauge to see what the EGTs are like, but that might not be for a while. Now I just have to pray the pulley doesn't separate.

[Bill]

i've got an old autometer EGT gauge kit if you want to borrow it for testing. used to use it on a 2-stroke snowmobile about 9 years ago. works great. let me know.