Oil leaking from.......?

[Expat]

Been working up to try and stop or reduce oil leaking, mainly from the chain case and quite badly now somewhere from the cylinder area, but tracking the actual source of the leak is proving difficult.

I had almost convinced myself that oil is leaking from the head gasket somewhere. There's quite a lot appearing on the left hand side of the cylinder fins and dripping/running off when on the move, some onto the carb and air filter cover, then generally making it's way lower and lower. Often upon stopping, oil can be seen to have dripped onto the top edge of the chaincase. If left on the side stand, quite a lot drips from the fins onto that area, and after a while, there's quite a oily patch under the bike.

There are signs of oil on the head fins and adjacent to the spark plug but not nearly as much as on the cylinder. This can't be from the head gasket as it's obviously lower down.

I'm sure the rocker feed pipe is secure and there really doesn't seem to be loads leaking from the rocker box or inspection cover gasket areas.

Thinking back, the leaking seems to have started or become much worse since I nipped up the head steady fasteners when the tank was off.

Is it likely this could have started the leaking by pulling up on the rocker box\head?

Is it even possible that oil can leak from the head gasket area? Are there oil ways through the gasket?


Any comment welcomed if others have had similar baffling (to me) experiences before I yank the head off perhaps needlessly.

Thanks

Steve

[JohnHewes]

I have a similar problem to a lesser extent which I put down to oil leaking down the head bolt holes and coming out at the head/barrel joint. John

[clive]

Oil has a habit of running around the cylinder especially when put on the side stand. The first suspect for me would be the rubber seals at the top of the pusrod covers, they need special washers which are often forgotten as they embed in the rubber and get missed when the old ones are changed. They need to be prised off. Even if they are there the seals always leak after a while and its usually a reminder that a decoke could be needed.
The leak higher up is possibly due to an uneven rockerbox cover, possibly due to tweaking the centre bolts which hold the head steady. The head gasket is copper and there are no oilways in it, however if it is leaking and the bore is worn it can result in oil being breathed out. I would buy a full gasket set and open up the head, keeping an eye out for those washers.

[saltbox alf]

If you have a rocker mounted de-compresion lever, that can weep a bit.

[clanger9]

Is the rocker inspection gasket OK (and do the two ends meet)? On my Lightweight, there was a small gap between the ends of the sealing rubber and on a long run it would blow a spray of oil out of the gap, which then dribbled down all over the head...

[Expat]

Thanks for all the tips chaps, much appreciated.

John, I can't quite get my head round oil getting down the head bolt holes, probably coz I've never looked close enough, or had the engine apart to see how this could happen, but if you say it's possible then it's something I need to consider.

I'll look closer at the inspection cover gasket as I've had the cover off recently to check rocker clearances and could have upset the fit of that sealing rubber, though the oil leak was present before. Likewise, I'll check out the de-comp lever in the rocker box.

Clive, I reckon the pushrods covers are the most obvious suspects. I've only just noticed how far into the head they are inset, so I will be following your suggestion....off with her head , in a week or two though.

I have a gasket set containing the rubber sealing collars and two O rings but no metal washers, can they be reused if in good condition? Hopefully there will be washers in place that can be re used, or if not there will be another order placed with AMOC!

Thanks again

Steve

[Mick D]

Hi

No reason not to re-use the push rod tube seal metal washers as long as they're not distorted / damaged / corroded - but for the sake of a few pounds I'd replace for future peace of mind.

Edited to add: Don't forget to clean the sealing surface of the bores in the head before you re-assemble.

Regards Mick

[dave16mct]

I wouldn't use the rubber sleeves for the pushrod tubes which come in the gasket set. They don't last very long at all. Use Nitrile or Viton 'O' rings available on-line from 'Simply Bearings' etc. The ones I used are BS210 Nitrile. 3.53mm section, 18.64 bore and 25.7 O.D. You can either remove a section of the original sleeve and use one O ring. Or stack 3 or 4 rings in together.
They don't leak and last well.
Dave.

[Pharisee]

I wouldn't use the rubber sleeves for the pushrod tubes which come in the gasket set. They don't last very long at all. Use Nitrile or Viton 'O' rings available on-line from 'Simply Bearings' etc. The ones I used are BS210 Nitrile. 3.53mm section, 18.64 bore and 25.7 O.D. You can either remove a section of the original sleeve and use one O ring. Or stack 3 or 4 rings in together.
They don't leak and last well.
Dave.

A good tip... thanks. I've just replaced the cylinder head on my 18S and used the rubbers supplied in the gasket set (not knowing any different). Should they start leaking, I'll use o-rings but I'll try to source some 'Viton' ones rather than 'Nitrile' as they are better with hot oil.

[Expat]

More great tips, thanks Mick.

Dave, your info on 'O' rings is just what I wanted to hear. I had read about them elsewhere on the forum and was going to search again.
After reading your detailed post I remembered where I'd seen some rings in a store cupboard at work so went to check. Can you believe there's a bagful of viton rings, the exact size you quoted!

Result Boss said help yourself, so I did. Couple of dozen in my sweaty palm :

Feeling more positive about sealing those pushrods tubes and Pharisee, I read the same things about viton too.

Good times, Christmas came early. Just gotta do it now