Broken Turbine Shaft
 

Ok, so here's my story: I bought a pair of used turbos and installed them. At the same time I did the vacuum hose job among many other things. I was done with everything late sunday night and took it out for a drive. I got on it a few times and I noticed that there was a sound like compressor surge coming from the engine bay. I was running with my boost controller turned off so it was only ~7psi. I could hear the bypass valve when I let off. so I'm thinking that it is from the secondary turbo. Anyway, i run it up to about 5000rpm in second and then poof.......instant, constant smoke screen. i baby it home, smoking profusely all the way. I ended up pulling them off monday morning. I snapped the shaft next to the turnbine wheel on the secondary turbo.


my question is, what are some possible causes for the shaft to snap at such low boost levels?

if the charge control actuator was not working properly, could that do it? due to compressor surge.

I ended up rebuilding my original set and put them in there, but i am not boosting until i figure out what the problem is.

I'm going to check the vacuum and pressure readings at various points in the system to see if everything is working correctly.

Does anyone have any ideas why the shaft would just break like that?

i'll try to post pics later.


Thanks,
Ryan

Ouch. That's some bad luck :( I hope you got those turbos for free or have some money back guarantee.

How was the condition of the turbos before you put them on?

I've never seen one fail. Only thing Ive seen on stock twins are stuck turbines or the nutt came off the shaft and shaft an wheel exit car.


For it to fail I'm going to guess lack of oil to turbo's.

Check the inside of the turbine housings. If there's a groove carved into the housings, then that's your root cause. When the turbine shaft gets too much play, it starts to wear a groove into the housing surface and, eventually, that groove can get deep enough to start catching the turbine blade. At 100,000 rpm, guess what happens .... the point of weakest mechanical strength gives; either the turbine shaft cracks or the turbine blade shatters. At this point, I'd be thankful that the blade is still relatively intact. I don't know how you clean out metal shards INSIDE the rotor housings .... that is, other than pulling the engine and rebuilding it. :eek:

That sucks, dude. I know your pain. I've gone through 3 sets of turbos myself. I learned the long and painful way that rebuilt/used turbos are always a risky adventure. Well, time for a new set .... or perhaps it's an opportunity for a new adventure - single turbo. ;)

the turbos visually appeared to be in good shape.

I think they were getting plenty of oil....hence the smoke screen; Spy Hunter style. and the other one was still in good shape. it broke on the exhaust side of the bearing/bushing.

the inside of the turbine housing was polished up nicely. the turbos appeared to have an acceptable amount of play. yeah, luckily, the wheel was still intact.


to top off my crappy couple of days, i took it in for an alignment today and i found out that one of my wheels is cracked. but wait it gets better......while one of my friends was doing the alignment and the tie rod was so corroded that it broke :mad:

when it rains, it pours. up until now, my car has been basically trouble free for 2 years/35k miles.

The problem with used turbos is that if the previous owner had an intake leak or other engine ailment that had the turbos working overtime on boost, the shafts get so hot that they will either melt :eek: or become so brittle over time that they'll just snap when the time to give up the ghost comes (which is usually when you're out in the middle of BFE testing'em out or trying to impress the hottie in the passenger seat :doh: ).

hey i had teh same thing happen.... look at it in a positive way.... law states if any emissions affecting part breaks that is non replaceable you are allowed to replace it with ANY part or setup..... now i have a legal single turbo rx7 but u gotta put in the paperwork... mine is still goin through... and i KNOW u cant find that shaft anywhere anymore

oh u get smog exemption too :D

well, I'm in Iowa. They aren't too strict on emissions. :)


back to my original question, could a faulty turbo control system ruin a turbo in a short amount of time? I don't want my current ones to break on me while i am diagnosing any abnormalities.