oil in intake manifold

[harold30]

hi guys,

earlier i removed the airbox to replace the afm. i also removed the rubber boot. inside the rubber boot i saw amount of oil coming from throttle body and some amount inside intake manifold. the worst part was it reached in air filter.

i searched around the net and some mention about blow by and it needs to rebuild the engine :( (hopefully this is not the worst case scenario as its expensive to have the engine rebuild). could this also be a cause of worn intake manifold gasket? (cheap solution :) )

the estimated mileage of the car is 130K - 140K as the odo stop working around 107K+

please share your experience about this problem and the solution. thanks in advance.

-harold

[harold30]

any inputs guys?

[nando]

try replacing the o-rings for the "tube of death" under the intake manifold. there's an upper and lower o-ring, you can't replace the lower one without removing the manifold, unfortunately, but that's still better than redoing the entire head.

Blowby can certainly cause this, but when there's a big vac leak around those o-rings it causes oil to get sucked from the head to the rubber breather hose (the one that goes from the VC to the TB) into the manifold. The tube doesn't actually go into the intake, though.

[harold30]

hey nando, thanks for you reply. aside from oil return tube o-rings, i also need intake manifold gasket, right? since manifold will be removed when installing those rings. any other things that i need to replace? i really appreciate your response because it helps a lot to newbie like me.

[nando]

yes

I'd get some new high pressure fuel hose as you have to pull the fuel lines off the injector rail, and they could be brittle if they're original. you could also replace the o-rings on the FPR and injectors. Good to have around at least in case one of them tears.

[harold30]

noted all things needed as you suggested. will post update here after the work. thanks again!

[bmwstephen]

i'd also run a leak down test to see if you are blowing oil past the valves. also if the rings are worn between the oil return tube, wouldn't his engine block be covered in oil?

[nando]

no, because air is being sucked in, not pushed out. most of the oil drains on the passenger side of the head, the tube is mostly to equalize head/block pressures and provide a way for them to be vented into the intake stream.

it's very well possible that it's caused by blowby/worn rings, but it's also possible to be a simple O-ring problem.

[harold30]

update: i did everything as suggested by nando and drove around the city for few hours. so far so good...

@nando, thanks for your insightful advice...