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1995 R33 Gtr Oil In Intake Pipe

judasentinel

By judasentinel,
in Engines & Forced Induction

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judasentinel Explorer

judasentinel

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I have a 1995 R33 GTR, and have been noticing oil coming into the intake pipe between the rear MAF and the rear turbo.

Someone suggested it could be from the exhaust crankcase ventilation (PCV) connected to the rear intake pipe, so I installed a catch can between the pCV and the rear turbo. However, the oil is still showing up in the rear MAF intake hose. I see oil coated on the turbo side of the MAF.

I have twin BOVs recirculating back to the Y pipe between the turbos, and when I rev the engine, I can see the air coming back out of the rear MAF (and not the front). The front MAF and turbo intake pipe are clean, which makes me think that the oil might be coming in from the rear turbo. This theory however, seems to suggest that the rear turbo may be leaking and blown.

However, the car boosts fine, all the way up to 1 bar without any hesitation. If the rear turbo was blown or had issues, would the car still boost? There is no oil leak under the car, and no black or blue smoke coming out of the exhaust. It idles fine as well.

I am totally stumped. I dont want to push the car if the rear turbo is blown, because some people have suggested it might be, but then others say that if it were, I wouldnt be able to boost the car to 1 bar.

Any ideas or suggestions to check?

Please help me as I want to make sure that the car is fine.

Thank you,

Munib

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https://www.sau.com.au/forums/topic/459082-1995-r33-gtr-oil-in-intake-pipe/
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djr81 Grand Master

djr81

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The blowby that gets sucked out of the head by the turbo (As opposed to the drivers side which goes into the engine on over run) goes to the rear turbo. This is almost certainly what you are seeing. Usually it ends up dripping out of the bovs. Even the crack pipe priced Nismo catch can doesn't stop it from happening.

judasentinel Explorer

judasentinel

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So how does one discern if it is the blow-by oil or the turbo is shot/leaking oil from the compressor side? If there is a compressor oil seal leak, will it also go into the intake piping? If so, how do we determine what is actually happening without removing the turbo piping?

Also, if there is an exhaust oil seal leak, will that also cause the oil to come up front of the turbo towards the compressor and go into the intake piping?

Surely, there would be a way to identify if the oil is from the blow-by or the turbo oil seal leak....?

judasentinel Explorer

judasentinel

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In addition to this, I do not see any oil at all in the catch can....maybe a tiny droplet, but that's all. And while the car is running OR I am revving the engine, I do not detect any suction from the catch can into the hose I am running to the rear turbo-MAF intake pipe. If this means the turbo is not spinning, it wont be sucking in any air from that hose, could this also be causing the recirc from the BOV to come out of the rear MAF? When I let go of the accelerator, I can see air/oil blow out of the rear MAF filter. This has me perplexed.

judasentinel Explorer

judasentinel

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If it is just blow-by coming back from the BOVs, and oil is returning with it, why is it escaping though the rear MAF only, and out the rear filter, and getting sucked in by the turbo since the whole point of recirc is to keep the metered air within the intake system?

I dont know if what I am saying makes sense....the BOVs recirculate air, it comes back into the MAF-turbo pipes (through the Y-pipe that connects to both turbos), and ideally, should at stage be sucked back in by the turbos. Instead, it is escaping out of the rear MAF...

fatz Grand Master

fatz

Posted
Posted

If it is just blow-by coming back from the BOVs, and oil is returning with it, why is it escaping though the rear MAF only, and out the rear filter, and getting sucked in by the turbo since the whole point of recirc is to keep the metered air within the intake system?

I dont know if what I am saying makes sense....the BOVs recirculate air, it comes back into the MAF-turbo pipes (through the Y-pipe that connects to both turbos), and ideally, should at stage be sucked back in by the turbos. Instead, it is escaping out of the rear MAF...

That is just because of the stock setup it takes the easy way out

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