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High Flow Turbo, Then Detonation Problems......

yug_r34

By yug_r34,
in Engines & Forced Induction

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yug_r34 Enthusiast

yug_r34

Posted
Posted (edited)

Hi all,

Just hoping someone out there can help me with a problem my old man is having with his ST185.

He's getting white smoke coming from the exhaust & we're not sure where it's coming from. His mechanic told him it was the turbo, but upon removal, we found oil between the AFM & the compressor inlet.

A little background.......

Dad bought his GT4 a year ago. Blew a little smoke, but not too bad, mainly on start-up. Turbo started leaking water behind exhaust manifold (in the end it was the water feed gasket). I suggested changing the turbo for a high flow one (corruption!) which he did, along with a s/s dump & exhaust manifold (the type you see on e-bay).

Engine started detonating, which was tracked down to a cracked rubber hose between the compressor outlet & i/c inlet. Changed that & detonation still happens a little, but not as bad & above 4500rpm, but still not good.

Ok, now for the questions:

1. Is the detonation because of the high flow? How do we fix it - programmable ECU, bigger injectors, etc....

2. Where the hell is the oil coming from? I own a skyline GTR & I realise that with high revs some oil can make it's way from the rocker cover to the linlet duct, but the old man drives his GT4 like a volvo (ha ha ha) & this pretty much eliminates the possiblity of oil getting there under high revs.

Like I said there is oil before & after the compressor & in the intercooler, but not at the throttle body.

I'll post pics tommorrow to give you all a better idea of what I'm talking about.

Help please.........

Here's the AFM, the breather is between the AFM & the compressor inlet, so the AFM is getting pretty dirty.

post-7282-1142460818.jpgpost-7282-1142461000.jpg

Edited by yug_r34
yug_r34 Enthusiast

yug_r34

Posted
  • Author
Posted (edited)

Ok, I know that the e-bay gear leaves a bit to be desired, but changing dump & manifold shouldn't cause all these hassles.....

Can someone suggest where this oil is coming from, I think it's from the rocker cover as the hoses connecting the rocker cover & the turbo inlet pipe have oil in them. But what would cause oil to reach that far? Maybe blow-by & worn valve stem seals?

Cubes: White smoke happens when on boost, hard accelleration, maybe oil seal on turbine?

Edited by yug_r34
Sydneykid Grand Master

Sydneykid

Posted
Posted

Oil in the combustion process causes detonation. It also coats the inside of the intercooler and oil is a great insulator, so you lose intercooler efficiency. Higher inlet temps cause detonation. Maybe the oil is the root of all of the problems. Try a temporary catch can (eg; Coke bottle) to make sure all of the oil stays out of the inlet. You can then measure exactly how much oil it is. Flush out the inside of the intercooler with 50/50 metho and kero, keeps flushing until it comes out clean. Wash with water and let dry in the sun.

Hope that helps

:P Cheers: D

yug_r34 Enthusiast

yug_r34

Posted
  • Author
Posted

Thanks Sydneykid, I didn't think that the oil could cause so many problems, but what you say does make sense. I'll do what you've recomended.

Originally we thought it was the turbo oil seal so we've pulled the turbo off for reco. Do you think we refit the turbo & try the catch can, suppose gaskets & a can are cheaper than a turbo rebuild.

Sydneykid Grand Master

Sydneykid

Posted
Posted
Thanks Sydneykid, I didn't think that the oil could cause so many problems, but what you say does make sense. I'll do what you've recomended.

Originally we thought it was the turbo oil seal so we've pulled the turbo off for reco. Do you think we refit the turbo & try the catch can, suppose gaskets & a can are cheaper than a turbo rebuild.

Don't bother with a can to start with. Just use an old coke bottle and a piece of suitale size hose for testing. Cost = zero. If it makes a difference, then go out and buy a nice shiny one.

:) Cheers ;)

rob82 Mentor

rob82

Posted
Posted (edited)

I would be checking that you PCV vavle is working as if it is blocked it will pressurise your entire crankcase including rocker covers which may be causing excessive blowby. You'll be able to blow thru it only one way thou; towards the intake pipe.

Edited by rob82
NAman Collaborator

NAman

Posted
Posted (edited)

I'd be looking at the turbo

Oil is getting into your engine- I recon from the turbo get it checked

Maybe get the various gaskets checked as well [head, exaust, various turbo gaskets]

But a good clean of the pipes maybe all that is needed

I'm no mechanic but this is my two cents!

Edited by NAman
BHDave Grand Master

BHDave

Posted
Posted
I would be checking that you PVC vavle is working as if it is blocked it will pressurise your entire crankcase including rocker covers which may be causing excessive blowby. You'll be able to blow thru it only one way thou; towards the intake pipe.

A busted pcv valve wont pressurise anything as there is a straight vent on the rocker cover running to the inlet pipe.

The pcv valve is an emmisions device that it sucked open by vacuum in the plenum and it is blown closed under boost so under boost any blow by will go out the breathers anyway.

yug_r34 Enthusiast

yug_r34

Posted
  • Author
Posted

The pcv valve is an emmisions device that it sucked open by vacuum in the plenum and it is blown closed under boost so under boost any blow by will go out the breathers anyway.

BHDave, does this mean the boost will blow by & out the breather, into the turbo inlet pipe? Along with some oil?

rob82 Mentor

rob82

Posted
Posted
A busted pcv valve wont pressurise anything as there is a straight vent on the rocker cover running to the inlet pipe.

The pcv valve is an emmisions device that it sucked open by vacuum in the plenum and it is blown closed under boost so under boost any blow by will go out the breathers anyway.

What I meant to say is that if it was stuck open manifold pressure would then pressurise your crankcase system causing excess oil to vent into the intake pipe. Its a common problem on VL's. And does cause lots of oil smoke when the car is on boost.

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