JacRyann

Overheating it could wear out the bearings. Excess radial play would have the wheel self-destruct against the compressor housing? How much play do both of your turbos have now?

Player0

Oh! I've been listening to the video! It's subtle, but the turbo noise changes a little before it explodes. It sounds more... grindy. I don't think a stone got in. I think it wore loose.

Player0

Here's the video. Skip to 20:40 to see the groundhog that cursed me right before the turbo shatters.

https://vimeo.com/130509803

divil

Nice driving up to that point. I was in that run group too. The noise in the video is weird...sounds like a siren!

Player0

Thanks, were you one of the red 951s? Yeah the siren noise is the hot side I think. I guess it still spins somewhat. I'm not sure why it's not shattered too, but it seems typical.

divil

Yep, red 89 951, #811. I'm not in your video though - my plate has my rennlist name on it

lejams

Yesterday I heard about another guy here in Atlanta who found his impeller in the air filter. Spoke with Charley who owns Evergreen Turbo. When the impeller breaks off and is thrust out into the filter, it's called a burst. A burst condition is caused by a bearing failure which destabilizes the axle allowing the impeller to make contact with the housing. Following this, when the axle breaks, if the engine is under acceleration/boost, the compressor wheel is pushed out by the exhaust pressure resulting in a burst condition. When mine went, I had just shifted into 4th and hit full boost when it popped, so there is a correlation.

Good catch on your video. You were on boost when it went, so the burst theory sounds about right.

Sounds like we both had bearings fail. Different things can cause bearing failures. The turbo auxiliary pump on mine had been making some odd noises prior to the failure, and I had not gotten around to replacing it. If it wasn't working properly, it may not have been cooling down the turbo and allowed damage to the bearings.

Additionally, I knew #3 was scored for the last 10k miles. When the head was pulled, the scoring had graduated to more of a galling. This could have contributed some metal contamination into the oil that also compromised the bearings. Charley has seen this many times.

lejams

I think it is the cold side making the noise. When the bearings fail and the compressor wheel starts to wobble or vibrate, theoretically it could produce some harmonics.

Player0

Ugh, I don't want to hear about galling and shavings getting in to the turbo. That makes me not want to put in the new turbo.

How do you prove that this happened? Are there any signs on the turbo itself to suggest it?

Are there any pre-filters that could be put on the turbo oil line?

lejams

I'm not saying this is your scenario. I had known scoring for some time that could have "possibly" been a contributor. My gut feel leans more towards the pump not working right allowing the bearings to over heat.

Different things can compromise the bearings, outside of a defect or normal wear, heat and/or contamination would be the most common.

Until the turbo is taken apart, won't absolutely know, but this is a reasonable assumption at this point.

lejams

Exactly, I agree. Haven't measured it, but there is definitely too much axial play prohibiting rebuilding it.

lejams

I just bought a turbo from a RLister Brian, (the edge). He had a prefilter on it. Might be something to check into.

Player0

Just noticed that the turbo shaft left in the compressor wheel was bent. The shaft is snapped off flush so it had to have bent before breaking. The turbo was spinning before it broke so the only way for it to have bent like this was to have seized up very suddenly.

I was using Brad Penn 20w50 and a Lindsey Racing oil line. I wonder if either of these were inadequate for the k27-8?

Does the 944 motor tend to have any turbo feed starvation issues? I'm betting one of the relatively new turbo bearings seized up, and geez, I would think it would have to be an oil issue.

reno808

never had an issue with 20w50. whats Lindsey Racing oil line? Most of time i hear Lindsey racing its always blowing up

Player0

http://imgur.com/a/a667b

Got the turbo off finally. Found the giant hole. Still finding pieces of it all over the engine bay. And also inside the intake and cylinders. I've been pouring thin oil in to the intake valve holes as well as the spark holes and using a vac to suck all that oil back out. I've flushed it a few times. I had noticed little specs of turbo dust resting on the intake valves so I wanted to do whatever I could. Short of taking the head off. I really just don't want to do that right now.

I cleaned out the intercooler with some carb cleaner and a hose. Got a bunch of shrapnel out. The tank ends look clean but I'm not sure what's in the fins. Suppose I'll have to junk it :P

Now just waiting on all sorts of new parts. Maybe the hard part is over with?