Oil filler cap leaking

[Mongo]

Hi all,
My oil filler cap has been leaking for years quite badly iv tried aftermarket rubber seals, genuine volvo seal, home made seals and a new cap and it still leaks. Has anybody else had this? The only thing i can think of is on the cam cover there is a small breather hole between two bores (3+4) i think and i had it blocked off after a diagnose of a bent rod because it was leaking oil after they resealed it. Any idea would be helpfull getting on my nerves a bit now.
Thanks

[nobananas]

What about the breather pipe to the left of the cap, is it leaking or split at all ?. The other thing could be that the PCV system needs and overhaul and you are getting excess pressure building up that's pushing oil past the cap seal.

[Mongo]

What about the breather pipe to the left of the cap, is it leaking or split at all ?. The other thing could be that the PCV system needs and overhaul and you are getting excess pressure building up that's pushing oil past the cap seal.

Yea breather on the left is fine ive checked it a few times. Pcv was renewed when i done all the work but im goin to be fitting a catch tank soon so ill be replacing all the pcv again. I might try unblocking that breather hole between cylinders on the cam cover now its sealed properly just left it blocked off for the last few years. Its there for a reason i spose.

[nobananas]

Don't think the other hole goes anywhere. Another possibility is that the neck that the oil filler cap sits on top of is pressed into the cam cover, there's a chance it could be leaking where it's pressed in .

[Mongo]

Don't think the other hole goes anywhere. Another possibility is that the neck that the oil filler cap sits on top of is pressed into the cam cover, there's a chance it could be leaking where it's pressed in .

Thats a good call i didnt think of that its so hard to diagnose because if you leave it idling it doesnt leak so youve got to drive it and by the time you pull over its all arround the cap and cam cover. Ill try the dip stick to see if ive got smoke in the tube.
Cheers

[weagie]

Mines does the same, at first I thought it was spillage and cleaned it up but is covered again.

[Mongo]

Mines does the same, at first I thought it was spillage and cleaned it up but is covered again.

Pain in the rear aint it deep down i think it leads to pcv but it dad have a new one not so long ago so i will redo it and try again.

[Harvey]

Try putting a latex glove over the oil filler hole cable tie it in place start engine if it inflates at tick over, or when engine revs up there is to much pressure in the crankcase.
Does the 850 engines have a grid in the neck of the filler like the s60R engines if not don't try this unless you can stop it getting sucked into the engine.

[960kg]

I have the NORMAL flimsy smoke coming out the dipstick but this is not a case of PCV blockage as one has merely given the blowpast or crankcase pressure a different opening of release instead of going the normal route!!

When you have oil squirting out the dipstick hole, as i have seen on engines, that is the time to worry.

The hole in the head is there for a reason on all whiteblocks. It must be there to allow crankcase pressure to escape when the PCV has a blockage resulting in oil under the spark plug cover and will prevent main bearing seals from blowing. It is really a safety valve which i believe you have blocked up!

As you are producing so many brake horsepower why don`t you do a compression test to see if you are within limits which will give an idea to blowpast etc.

[Harvey]

When I did PCV which was very blocked I had a fair bit of steam coming out of the dip stick tube when the engine was hot,but no oil.

A latex glove would inflate very well at tick-over and the oil cap would dance if it was placed on the oil filler neck.

After it was done the engine at tick over now has a vacuum present and the cap stays put when placed on the neck at tick over.

[merc85]

drive it a short distance with the dip stick partially out see if that helps?