Crankcase ventilation/turbo smoke

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Luke2152
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Crankcase ventilation/turbo smoke

Post by Luke2152 »

Having replaced all the standard inlet pipework with my own I'm at a loss for how to plumb the crankcase breather. Normally I would just vent it to atmosphere but when I do that the engine starts pumping out lots of oil smoke. If I block it the oil smoke stops. I can't remember exactly how the original breather was routed but I think back into the inlet before the turbo? That's what it looks like in the pic on the know your mk2 section here. I tried that and it made no difference as I don't think there is enough of a depression there at idle to create a good vacuum. Or maybe my turbo seals are just on the way out. So I tried (with a one way valve) routing it downstream of the throttle body which creates a very good vacuum and stops the idle smoke but as soon as you get into boost it smokes as the crankcase fumes have nowhere to go.

I'm presuming here the smoke is caused by the crankcase pressure making it hard for the turbo to drain back to sump and then it getting into the exhaust side. Could also be forcing it down the valve stem seals for the same reason.

Any suggestions?


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