Shaft Play

[talontsi01]

How much is too much? I know that it is alright for you to be able to move the turbine side to side. But my question is about up and down. How much is too much?

When a turbine gains more and more shaft play over the years, how exactly does that effect the turbos performance? Does the turbo work fine up to a certain amount of play, then just go bad when it gets beyond? Or, does the turbo gradually get worse with more and more play? I ask this because all of a sudden, I had no boost. I was boosting fine one minute and the next, I had nothing.

But back to the main question, at what point does shaft play start effecting turbo performance and how exactly does it effect it?

 

[ZachM31]

i dont think shaft play is good at all, my compressor doesnt move up and down (i am sure at a microscopic view it does) but nothing that i can see or feel. back and forth movement should be minimal, just enough for the shaft to expand and sit tight with the bearing, if it is extremely loose, check and see if the compressor retaining nut is loose, if it is, the shaft will be able to spin inside of the turbine, therefore reducing boost pressure... thats all i can think of as for the turbocharger internals affecting boost, you say it would be boosting one second and not the next? does that mean sometimes it will boost, and other times not? or just that it would boost and then you would let off, and if you tried again it would jump to 0 and do nothing? do you have a boost gauge? MBC? i'll try and help you out...

i just read your post again, to answer the second part, shaft play will cause drag in the turbo, so it can't spin as fast and make pressure, are the compressor blades fine? or are the chipped or broken? you could also look into the wastegate, a mechanical problem with that could allow it to not seat properly, creating a large exhaust leak around the turbo, a bad wastegate valve will seldomly keep the turbo from producing the normal amount of boost.. so basically the system must produce enough revs just to overcome the leak before producing any boost.. <-- the last part was derived from pg 178 of Maximum Boost By Corky Bell... i didnt know how to put it in my own words... and i know enough about plagiarizm. <-- except how to spell it haha

 

[talontsi01]

I was driving one night and I was boosting fine. Then upon acceleration one time, I had no boost. I could barely get to 0 vacuum. I took it home, let it sit. Tried boosting again, no luck. I believe my gauge still works because the vacuum still seems to read normal as I accelerate/decelerate. I have a EBC -AVCR and autometer gauge. Its set at 15 psi. I've messed around with different settings now that this has happened. When I would accelerate hard, there would be a howling sound from the engine bay. I imagine the turbine actually starts to turn before any boost is made. I'm guessing thats what was making the noise, but still no boost. The compressor blades look perfect. The wastegate looks to seal normally. If the wastegate was the problem, wouldn't it sound very loud and almost like a machine gun? What I've narrowed my conclusion down to is that the little shaft play that I do have is disallowing my turbo from building boost. But I just don't understand how. I appreciate your reply.

Jim

 

[ddavisaf]

If you're not building boost then your wastegate actuator could be holding the flapper open. Or you have a boost leak. Or your turbines are catching on the housing to the point where it won't allow you to build boost. You're correct that the turbine is always spinning.... as long as your car is on the turbine is spinning. Check for shaft play. Then see if your wastegate came off the flapper.

 

[TurkF26]

back when i had my 92 TSI AWD, my 14b one day decided to crap out. It was the same thing you are having. All of a sudden it sounded like a police siren and would not build any boost at all. when i got home i pulled that turbo off, it had more shaft play, but what had happened was the turbo blew the oil seal and was shooting oil all out through the intake side all through the IC piping.

so it sounds like the turbo took a crap.

 

[ZachM31]

as long as your car is on the turbine is spinning.

that is not entirely true, the turbine stops spinning before the engine stops turning. like when you shut it off, the turbine will stop a little bit before the engine stops. i dont want to be a smartass or anything, just wanted to point that out. but yes the turbine will be spinning anytime the car is running.

 

[ddavisaf]

*sigh* Okay fine