Diagnosing turbo - failing bearings??


Coincidently the days after I put in my MS2 Extra I noticed my car wasn’t boosting nearly as fast. I have my AFR’s running decent and then got a VVT controller and thought - ok all my problems with slow boost will go away. Well they didn’t. I highly highly highly doubt its ECU related though.

My spool is bad - In 2nd gear at 2K if I hold there then go WOT, I get 5psi by 3600rpm!! 10 by 4500 and bam 12 at 4700. Today on the way to work after I was fully warmed up and had boosted under load a few times I thought I’d rev the car in neutral while driving down the road. If I do that it spins to around 5k then hesitates then my boost gauge flutters at about 5psi then the revs start to climb past 5K – I don’t think that is normal?
I also drove with the top off yesterday (finally had a day above 12 Celsius – arghh Canada !!) and with mild boost between shifts I can hear the BOV but also the sound of the turbo spinning. It’s a very light sound, barely noticeable (I can only hear it with the top down) but it sounds like what you would hear as your turbo is spinning down – almost a bearing rumble??

I’m going to take another look at it from the intake side and feel for play in both axis and see how it spins by hand. Can I also have someone rev the car under slight load and watch it spin down? Or will this not have it spinning fast enough to tell ?

I would normally take it off and get it diagnosed but I use the car for work. My plan is to find out before I dismantle then order another one and make the swap when it arrives to minimize downtime.

Thoughts please?

 

Shaft play?

 

Pop off the intake and check for shaft play and see if it spins freely by hand. IF thats all in order next logical place to look would be your wga can and boost controller if you're using one.

 

There was a minute amount when I recieved it and it had sat for a long time.

I'm going to get out my dial indicator and if I can fit it in there get some numbers. I suspect there is more now, how much and in which direction we shall see!



I should add - it will boost all the way to 12+ psi if I keep in it but by then I'm in a new province!! So I suspect the WG and MBC are doing an ok job.

This Thursday night I have arranged another vehicle so I'm going to take of the DP and check hot side.

 

You don't need the dial indicator. If there is any thrust on axial play or the compressor touches the housing, it's over for the turbo. I know Garrett's are overpriced and all, but mine has been fine for 2-years of racing.

 

Landrew:

Clear out your PM's.

 

done

 

Thanks for the PM. I'll take a look around.

 

I have to ask- how is boost response after going to redline at WOT, changing gears and going back to WOT? Does it seem normal or almost normal to maybe it's a bit slower? Sounds like what mine was doing in the month or so before it failed. Oddly enough, there wasn't even that much shaft play after it failed...so little that neither wheel made contact with the housing. Only the compressor blade "wiped off" some of the intake grime at the compressor inlet. It didn't even make a scrape in the metal, proving that you can have a bearing failure without much play.