Calling all turbo gurus. Weird failure, looking for a diagnosis.

[bigbird94]

A little background on the car...

Stock longblock
Stock drivetrain
Stock ecu/560cc injectors/2g maf
14b w/7cm hotside
4an turbo oil feed w/ stock return
Short route FMIC
PCV routed properly and functional
Always ran slightly rich but never any issues and pulled great @21-22psi

I've ran this same set up for 3 years and 12k+ miles with no issues until this last week.

I was doing a pull merging onto the highway (steeply downhill) at the top of 3rd gear when I heard a pop and saw plumes of smoke behind my car. I got off of the highway as soon as I could (terrible timing) and limped it home at 2-3k rpm smoking the whole way.

When I got home I was about 2.5 qts short on oil, stupid of me, I know, I didn't realize I lost so much. I checked the magnetic drain plug and it only had a silvery coating on it, no grit. I'm thinking the bottom end made it out ok but I worry about debris in the oil pan.

When I went to check the turbo it was clear the turbine snapped. The compressor wheel was just sitting in the compressor. The turbine wheel was lodged in the o2 housing with the rest of the shaft and a bearing. The only piece I haven't found is the compressor nut. My oil feed was clear of debris and return was fine as well.

My question is, what could cause this to happen? Bad fuel? High EGT's or back pressure?

The turbo boosted fine and had no shaft play the day before. I want to say it's just an old turbo letting go but I would have expected some signs first.

Also, is there anything I should worry about as far as the engine sucking in debris? The spark plugs were all fine but I have my doubts.

Is it possible that any debris could have made it up and into engine or even went down the oil drain into the oil pan? And lastly what could have cause my turbine to snap like this of it wasn't a lubrication issue?

If you have experienced a similar problem, or have an idea as to what happened please speak up.

And this may sound ridiculous but is it possible that I was going down a steep enough hill that the oil drain was getting blocked by oil that was sitting in the the pan? Just a thought.

 

[donniekak]

I've had a few 14b's fail in that way. Usually it's the earlier ones without the reverse threaded compressor nut. In any case it's from overspeeding. Running a 14b at that boost level is running shaft speeds over its design limits.

 

[bigbird94]

I've had a few 14b's fail in that way. Usually it's the earlier ones without the reverse threaded compressor nut. In any case it's from overspeeding. Running a 14b at that boost level is running shaft speeds over its design limits.

I'm not sure if this was the reverse threaded 14b or not, the compressor nut and threaded piece of the turbine shaft were the only things I didn't find. Your explanation does make sense though. Just an old turbo being pushed too hard I suppose.

Did you experience any engine failures when your 14bs went out on you?

 

[donniekak]

I've never had a turbo failure damage the engine.

 

[dustyboner]

Have you checked your intercooler for compressor nut?

 

[JusMX141]

Older right-hand threaded 14B's will definitely have the compressor nut come loose any time they're pushed. These turbos typically have a part number ending in 01010 or 01400, but I've seen a couple early 01030 14B's with right-handed locknuts, too.

 

[Diamond Star Werks]

I've never had a turbo failure damage the engine.

I have. Pieces from a t25 ended up going into the combustion chamber caught between the wall and cracked the ring land and scarred the walls. Didn't know of the damage till I took it apart 20k miles later. At least that's the only traumatic thing I know that could have caused it. My tbelt stripped at the crank about 5k or so after the turbo blew. I pulled the plugs and seen something I thought was a chip from a valve sitting on the piston in number 2 cylinder. Pulled the head thinking I had to fix it and it turned out to be part of the journal bearing from the t25 that blew and got replaced 5k miles earlier. I never could figured where that was sitting that it could end up there that much later.

On the subject for OP, my sister subaru with a BNR 16g (mhi 16g adapted to subie housings) just blew the other week. Shaft snapped off on turbine side. I found the wastegate nipple missing and the T in the line coming of the comp[ressor housing was broken. So it broke due to overspinning.