Broken crankcase under camshaft

I don't think it's worth the fiddling around to try to remove one case, If as Colin reports there is some swarf on the magnet a complete strip, investigation and thorough cleaning would be a good idea.

Yup, the swarf report changed my mind, I guess I'd have to look inside now.

hi colin, another possible theory is one of the stelite pads has come off the cam follower,allthough very rare its not unheard of,especially if a high lift cam is used

Reading Colin's post from earlier when he had the canmshaft chain tensioning issue he noted he had had the follers refaced. Could be the brazing was weakened if the grinding put too much heat into the follower, is stellite magnetic ? , if so a hard material stuck to the magnet says it looks like it is the stellite pad let loose.

i guess all we can do is speculate until he opens it up.

Took the big crankcase filter out tonight and out dropped a roller bearing. I am now presuming that the drive side main bearing has broken up.

The main bearings were the original ones fitted in the factory and have never been out the cases. They were cleaned and oiled. There were no tight spots or any feeling that the bearings were not spot on. When I put the cases together they seemed fine and gave me no cause for concern.

I have no idea what could have caused the bearing to break up like that.

Could one (or more) of the rollers have simply dropped out of the bearing cage unnoticed, as you assembled the crank and cases?

Oh well, at least you know what caused it now.

It does sound like a heartbreaker but off hand nothing that cannot be fixed. As LAB says you have more of an idea of what is going on now. Pulling it apart will be interesting.

Cookie said:

Pulling it apart will be interesting.

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Taking and posting pictures would be doubly so.

Heck, if we were over there I'd have the air wrench ripping by now.

Cookie said:

Heck, if we were over there I'd have the air wrench ripping by now.

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Beers and and air wrench. I think he has enough problems as it is. :lol:

Colin, Although you are obviously disappointed, this sounds like it might be less of a problem than some other possibilities. You were going to have to take it apart anyway and now you have a good idea what the problem is, plus you haven't actually blown it up which would have been inevitable if you had been less fastidious with your post-build checks or had just gone down the Araldite route. You will need new main bearings, a small weld repair on a part of the case that is neither stressed nor size-critical and whatever else you might find. If the cam is damaged you can repair one lobe at any decent cam specialist for not much money and if the follower is scored you may have to face it up. I would pay particular attention to the push rods-prior to reassembly, the kind of force required to damage the case could easily bend a push-rod if there was debris between it and the cam. good luck with it.

Depressing as it is, I quite agree it may not be all that bad. It is a lot of work though. I was a bit burnt today to find that in our moving some sort of solvent had hit the nice old paint job on the Norton tank. A bit more practice in blending paint I reckon.
A job rarely goes perfectly and there are ups and downs, just sorry some of us aren't nearby to lend a hand.

Just saw your tale of woe. Feel for you but it looks like you've had some luck (well not as bad as it could have been). At least it doesn't look like this I posted before.

Mine had been welded under the tach drive by a PO so something similar had happened on the opposite side to yours.
This was the real problem so don't feel too bad, at least it seems fixable without new cases. Have you got any pics? I guess the cases will need good degreasing for welding
Best of luck and hope you get it going soon.

Hello Collin, did you dismantle your engine to find what happened, it's been a while and I am interested to know the cause.
Last I read it seemed to be a main bearing roller.
Graeme.