Oil leaking out of filler neck...why?

foresthump · Post by **foresthump** » 10 Nov 2020, 06:58

2001 Volvo C70 coupe with built engine and suspension plus 5 speed manual, @400hp at tires.
Copious amounts of oil leak out of filler neck, with filler cap and rubber seal in place. It runs all over the surface of the head with gravity pooling it into the cyl 4 and 5 spark plug opening as well as running down the back side of the block.
This car is a daily driver as well as a HPDE participant.
WHY the leak?
As a daily driver, it leaks @ 1 quart every 700\800 miles. As a track car, it leaks 1 quart over a full HPDE day.
Is the leak created by any abnormal pressures within the engine? For instance high boost and/or constant high rpm?
I change the filler cap rubber seal with every oil change. Also I replaced my PCV breather system this year.
Any solutions please?

Post by **abscate** » 10 Nov 2020, 07:00

Put the glove on the neck and let’s see what the crankcase pressure is like

There is also sealer at the base of the filler neck which leaks on rare occasion

foresthump · Post by **foresthump** » 14 Nov 2020, 13:35

I spoke to a volvo mechanic yesterday who said he had seen this one time before. It turns out that the problem is probably not the filler cap/filler neck but instead either a loose cam cover bolt or a small crack in the cam cover. So, I should have an answer to that soon and will post here.

Post by **scot850** » 14 Nov 2020, 15:26

+ 1 with abscate on this. Before going down the 'big' issue route, check the 2 issues he mentions. The oil filler cap seal, especially aftermarket ones, can either be too thin or hard to seal correctly. Also check the cap itself is not clogged.

Glove test will also clear or fail the PCV system being clogged. If it is clogged, it will eventually blow out your cam and rear main seals.

That does not mean the other issues are possible, but check the easier stuff first.

Good luck!

Neil.

Post by **scot850** » 14 Nov 2020, 19:30

I should add that on some Volvos I have found the 2 'lugs' on the oil filler cap have been bent allowing a gap to appear. Sometimes bending them slightly will improve it but usually end up replacing the cap with a good used one.

Neil.

foresthump · Post by **foresthump** » 15 Nov 2020, 06:06

Thanks for all the helpful hints guys. Will put them all to the test. Also, I bought a new filler cap.