(Home) Oil from rockerbox into (big) air inlet hose

Is it normal (2CT) to find a puddle of oil inside when you remove the big air inlet hose with the air filter top? I find 5ml or so gather at the joint above the inlet manifold, below where the small hose comes across from the rockerbox.
It's a particular problem to me because the EGR bracket has chafed a small hole in the bottom of the large hose at that point and this oil seeps out over the engine and the ground underneath. I repeatedly patch the hole but I wonder if the presence oil there indicates another problem.
Is that small hose just to create negative pressure in the rockerbox or to deliberately inject some oil/mist into the airflow?
(I find that I need to top up the oil once between changes, which I do at 5,000km.)

- (#5978) Dave Mason, 29 Oct 02

Normal. There's always a degree of oil mist in the blowby gasses, it condenses out on the inlet hose.
You might want to try fabricating an oil seperator- I had one nearly sorted until one of the hoses kinked and had me believing that my turbo had failed...
There's even more oil gets into the intake via the turbo compressor seal. Add all that to the soot from the EGR, and you wanna see the mess...

- (#5979) david miller, 29 Oct 02

Thanks David. I've never seen a comment on it before. I too wondered about some kind of collector which would drain back into the rockerbox but I'll leave well alone.

- (#5980) Dave Mason, 29 Oct 02

David, I can't stop wondering about your remark, "one of the hoses kinked and had me believing that my turbo had failed".
The kink presuambly stopped air and oil getting into the big air inlet hose, and increased the pressure in the rocker box. So what symptom did you observe that pointed to the turbo?

- (#5981) Dave Mason, 1 Nov 02

What happens then, Dave, is that the turbo's bearing housing is pressurised also( via the drain tube to the sump). This pressure opposes the pressure in the compressor and turbine housings, and literally blows oil into the exhaust and to a lesser degree the inlet.

The seals on this type of turbo are dynamic, and depend on the positive pressure in the ends to force the seal against it's face on the shaft.

- (#6012) david miller, 1 Nov 02