I replaced intake manifold gasket about a month ago and at the same time cleaned it until nice and shiny on the inside. For some reason I still have a vacuum leak and yesterday I took it off again to investigate and found oil on gasket and in manifold. Could it come from the valves or does it come from flame trap hose? It wasn't a whole lot but enough to think twice about it and that I wanna fix it.

Thanks
John

I cannot believe the stock breather box is large enough to slow down atomized oil droplets so they will run back into the crankcase. I installed a racing style 1 L. catch tank and did away with the breather box all together. It is mounted next to the carbon canister. However, I have not had my intake manifold off again to tell if it works. The tank seems to collect only oil foam.

I noticed the same thing on my '92 B230F motor. The oil on mine is coming through the small vacuum line from the flame trap to the intake manifold. Have you cleaned the flame trap and oil separator box? I read somewhere that deposits in the separator can cause it to allow raw oil into the hose to the flame trap to be picked up by the vacuum line. It could also be increased blowby past the rings due to wear. How many miles on car? I plan on removing and cleaning my separator when the weather warms.

It's around 200k miles on it and just cleaned separator box a few weeks ago so it should be fine. What do you mean with "blowby past the rings"? Leaks by the separator ring seals?

I mean excess blowby past the piston rings in a worn engine. This could cause a little oil to back up into the bottom flame trap hose also. Mine has 219k and I suspect increased blowby is the cause of the oil being drawn into the small flame trap vacuum line. Like yours, mine is only a few tablespoons of oil.
Where do you think your vacuum leak is?

It comes from the flame trap hose. Probably more from the large one, connected into the accordion (AMM) hose. The oil is normal condensing oil vapor from the crankcase being driven by the blowby the PCV system is meant to recycle.

A certain amount of it is a sign of health, for if it stopped, you'd blow your seals. Of course, too much (and who can describe that?) may be a result of poor oil change maintenance over the motor's life. I haven't encountered that yet in a Volvo, but have seen excessive blowby in other ruined motors.
--
Art Benstein near Baltimore

A boiled egg in the morning is hard to beat.

A few table spoons maybee isn't anything to worry about then. Actually also I had a little gasoline in the throttle body, is that only because of a leaky membrane in FPR or could it have other reasons?