Oil cap leaking - a lot.

[Johnfm]

Replaced the rubber seal - still a lot of oil leaking though. Not just a weep.

Oil breather isn't blocked (I.e. I could blow through it easily enough) - but I note there must be reasonable crankcase pressure as oil wants to come out of the dipstick area too.

Any ideas? Is there a replacement oil cap that is completely leak proof?

[mbell]

Is the breather on the head clear (in the head)? Does it still leak in you remove Your breather?

Have you checked the compression on the engine? May be too much blow by.

[prezoom]

Mine leaked as well. I tried a number of things, but the easiest is to shim the rubber gasket between the gasket and the cap. A piece of thin cardboard from the back of a note pad was enough to stop the leak. Just cut a circular ring about the same size as the rubber gasket and give it a try. My piece of cardboard is still in place after about 6 years. If it starts leaking again, I think I will try some exotic higher priced material...........

Rob Walker
26-4889

[Johnfm]

Cheers. I think the shim is the way to go.

[john.p.clegg]

John
Yes,the replacements are readily available (auto jumbles),

maybe you need belt and braces...

just a bit of ally bent and shaped to stop the cam flinging oil onto the cap...

John

[Chris]

Years ago, I also fitted a piece of shaped aluminium over No 4 exhaust cam to prevent the oil being flicked onto the oil filler cap. No more problem
Chris

[Johnfm]

Don't think blow by is the issue - compression numbers are strong and consistent. But the dipstick is being pushed out a bit and a lot of oil is coming out of the filler cap - even after shimming the new seal.

Very annoying as the engine is running really really strong now.

[mbell]

Are you sure the blow by gases are able to escape via the breather and aren't having to force there way out elsewhere?

[types26/36]

Do you still have that conical filter/breather thing fitted? if so try taking it off, looks too restrictive to me.

[Johnfm]

Do you still have that conical filter/breather thing fitted? if so try taking it off, looks too restrictive to me.

Bingo!

Removed - cap leak now reduced 99% to a mere thin film.

Thanks chaps.

[EnfoKen]

I'm confused.
You had some aftermarket crankcase breather attached and removed it and now the problem is solved?

Thanks

[Johnfm]

Not solved, but greatly reduced.

How much air should I feel at the filler cap with engine running?

I reckon 'not much' - but I am feeling 'quite a bit'.

[jk952]

I had an annoying leak, couldn't solve until for whatever reason I shinned (had shawn? ah the humour of English.. think thank thunk etc.) a flashlight near the filler casting top and found a pinhole just below the cap, and I mean pin hole! A touch of metal repair epoxy and leak solved. Jk

[AHM]

John,

I did comment in the "Head back on" thread where you added the "Improved Breather" that the original is designed to benefit from negative pressure.

If you plug it in where it should go it might be better still!

[vernon.taylor]

Salut

I think the original vented to air through a long tube to the underside - would there be negative pressure there ?

I put a compressed air filter between the block and airbox - worked OK until the filter-mesh got clogged with oil at which point leaks appeared around the cam cover nuts. Took out the mesh-filter and it seems OK and still catch oil in the filter body.

@+

Vernon