rebuilt ct20 turbo not spining at idle

[ae86levin]

I have recently installed a factory ct20 setup off a 2L-T onto my 3L - pretty common mod.

The Turbo was old and the carbon seal was finished letting heaps of oil into the compressor and inlet.
I got a seal kit that effectivly converted the carbon seal to a dynamic. I had the new parts and the old shaft/wheels balanced by MTQ and have installed using their marks.
When rebuilding it the shaft turned well and felt much tighter (less shaft play) than previously. When I started the engine after putting it back together I noticed that the compressor wheel wasn't turning at idle. I does spin when you rev it a bit.
With the engine off it turns by hand without any noticable problems. When idleing it is very hard to move by hand.

I took it for a 400m drive round the block and can hear the turbo stop spinning when I'm of the throttle - makes a sort of zzzz sound.

My questions are:
Will a rebuilt turbo behave like this? Is it because the new journal bearings are tighter than the old ones?
Should it spin at idle? I never checked this when it was in 'original' condition.
Have I made a mistake rebuilding it that would cause it not to spin?

My searcing of google gives conflicting advice on this.
Some say it's poor oil flow causing it to lock up and others say it's normal for a rebuilt turbo to take some break in time.

[RAY185]

You tried to turn it by hand while idling?

I've never seen a turbo not freewheeling (spin) at idle. I'd suggest you have a bearing issue and would agree it may be due to oiling issues. Remove the oil feed pipe to the turbo and make sure it is not blocked. You should be able to blow through it very easily. This is usually what blocks up when people don't use turbo timers or forget to allow the oil to cool a bit by letting it idle for a minute or so before shutting the motor down after a hard slog.

I'm no turbo guru but theres something for you to check. Thought about ringing MTQ for advice?

[ae86levin]

You tried to turn it by hand while idling?

Yeah only after it was obvious it wasn't going to start spinning while idleing. I wanted to feel if it was locked up or not.

I will call MTQ on Monday to see what they think. It's probably worth pulling it apart again to see what's in the journal passages.

[80's_delirious]

i would say you have a problem.
I have rebuilt CT26 turbos myself, they spin freely by hand when on the bench. the fan will keep spinning for a few moments after a spin with one finger.
It also span freely with the engine at idle as soon as the engine was started

[ae86levin]

Well it seems the ct20 definetly should spin at idle.
I have found the problem was a piece of the rubber o-ring that seals around the seal plate was pinched off when I installed the seal plate.
It was in the area of the thrust bearing and I thibk it was forcing the compressor wheel into the housing once oil pressure was applied. The wheel was spinning fine by hand when the engine was off.
The wheel and housing aren't 'badly' damaged (slight grazing on the edge of the blades) but I don't think any damage on a compressor is good.
So there goes my $120 balance job and my compressor wheel / housing.


For anyone else doing this if the wheel doesn't spin with the blip of the throttle after rebuild DO NOT rev it to get it spinning.

Anyway it's all back together and working now - and the compressor spins at idle.
Will have to keep an eye out for another turbo to get the wheel and housing off it.

On the plus side I can remove and rebuild one of these in around 4hrs now.

[thrashlux]

well have done good and thanks for the heads up u got there in the end

where did you get your parts from and how much did they cost ?
did you get them from MTQ?
were they helpfull for guys wanting to do it on their own?

[ae86levin]

I got the parts from a seller on ebay in the US called 'Allzone' for under $50.
The only complaint I have now is that the piston ring on the compressor still alows a bit of oil through (not as much as before). Of course this could be because my compressor wheel isn't balanced following the contact with the housing.
MTQ were really good the guy offered me advice on cleaning the galeries in the turbo when I picked up the balanced shaft.

[thrashlux]

I got the parts from a seller on ebay in the US called 'Allzone' for under $50.
The only complaint I have now is that the piston ring on the compressor still alows a bit of oil through (not as much as before). Of course this could be because my compressor wheel isn't balanced following the contact with the housing.
MTQ were really good the guy offered me advice on cleaning the galeries in the turbo when I picked up the balanced shaft.

sounds great sure beats getting ripped off
thanks for the advice