Oil among cooling fins

[Bill18]

When I start up the A10 I am getting oil appearing on the cooling fins of the head and engine. Can oil escape through the head gasket? I have eliminated oil leaking from the rocker cover. The engine was rebuilt some time ago but has not been running until recently. I have kept the barrels lubricated while idle. The engine starts and runs - if a little slow to warm up and idle.
Bill

[beezermacc]

Hello Bill. This happened to a friend of mine recently. On his bike it turned out that one of his spark plugs wasn't seating properly and oil could be seen running out of the spark plug hole, then down through the gap on the outer edge of the spark plug hole onto the fin below. Sometimes spark plugs vary in thread length very slightly so a previous plug hadn't reached all the way down the plug hole allowing carbon to build up on the bottom thread in the head, so the new plug didn't tighten down fully. I lent him a plug thread restoring tap, job done! If you have been squirting oil down the bores it is also possible the oil has been exiting down the exhaust posts then blowing back along the fins. It is possible you have oil leaking from the head gasket but this would not normally allow oil onto the head. Regards, Happy New Year!

[Bill18]

Thanks very much beezamac. Yes I have been squirting oil in the spark plug holes and in the exhaust openings while it has been idle. I will also check the spark plugs. (Mine also is "not for the purist". I don't know what the forks came off and it has a Thunderbolt seat - still a beautiful thang.)
THanks again.
Bill

[manosound]

Bill,

You say you've eliminated the rocker cover,  how about the rocker box?  My guess,  and I suppose the most popular answer,  will be that it's leaking between rocker box and head.  Mine does it (birds do it,  bees do it...) This is pretty common due to the head steady tranferring vibration to that joint. Due respect to Andrew,  but I think the spark plug possibility is more obscure. If it turns out to be the plug, I benefit by learning somethiing new.  
 
Richard L.

[bsa- bill]

Bill I agree with Richard having gone through this myself

Go here http://www.audioworld.net/BSA/forum/index.php/topic,3385.0.html for more info also search for "rocker box gasket" in the search feature below your avatar

[orabanda]

Sometimes it can be leak(s) from either end of the rocker spindles (Acorn nuts on RH side, rocker oil feed banjos on LH side);  can be difficult to spot.
Richard

[Bill18]

Thanks to all those who replied. I did check the spark plugs and the problem is not there. I have also eliminated the acorn nuts - I replaced the soft metal washers and now no leaks. The oiliest part seems to be in the recess in the head  at the front . I will clean things right up and see if I can located where the leak starts.
Thanks again.
Bill

[beezermacc]

From what you say my money is on the rocker box gaskets. Don't forget the bolt on the inside at the rear.

[Bill18]

Thanks beezamacc. I will have a good look at the seal between the rocker box and the head. Luckily I now have a gadget for lining up the valve stems. What a job that is without one!
Bill

[Bill18]

I should have said a "push rod" gadget of course, not "valve stem". The error came to my mind's eye on waking this morning.
Bill

[madsens]

Hello gents
I have the same problem with oil leaking all over fins.
Being a complete novice on spannering A-10 I took a deep breath and then took of the rocker box and iron head. It seem to me like its leaking from the front part of the head, thats where the coppergasked is black anyway... But I would like all you experts to bid in with comments and views, please

Kind regards
Joergen

[A10Boy]

Hi Joergen

I agree it looks like your head gasket has been blowing. I would suggest that you give is a good clean up and de-coke the head. Then when you come to re-fit the head, use a new head gasket and new iron head bolts. You might also clean the threads into the cylinder block to make sure the bolts go in without binding and giving a false reading on your torque wrench.

You will need to anneal the head gasket before fitting, this involves heating it on the gas until it glows cherry red then plunge it into cold water. This softens it and allows it to compress as required when tightened down. Torque the head bolts to 35 Ftlbs [is what I use] and all should be well.

Good luck

Andy

[muskrat]

 G'day Jorgen,
                   yep she has been blowing at the front left combustion chamber and blowing the oil out of the front drain holes.
Check head for flatness on a thick glass table top. It may need a light skim.
Threads are 3/8"BSF. The gasket is annealed  right if you can mark it with your finger nail.
Cheers

[madsens]

Hello Gents

Closing info on my case - after de-coke and valve lapping and change of all gaskets and bolts my A-10 is back together again!
As said before I'm a complete novice in working on 4 strokes, all these valves and pushrods... and it was with held back breath I did the starting routines - but lo and behold, she fired up on second kick, and acted perfectly on the short test run, and so far no oil leaks ( from the top anyway).
Without this forum I would never have dared doing open surgery on my A-10.
I might not be a very frequent contributor but use the forum as a kind of big DIY manual.

So once again thanks a lot for keeping this place alive and kicking! 

Regards
Joergen