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+--- Thread: block to crankcase joint - external seal? (/showthread.php?tid=6378)
RE: block to crankcase joint - external seal? - John Mason - 16-07-2021
I know it sounds obvious but has anybody tried thread lock on the crankcase to block studs to keep them tight or is the problem more than this. I am aware of having to use heat to removed them should that be necessary and the problems of distortion with an alloy crankcase.
John Mason.
RE: block to crankcase joint - external seal? - Colin Morgan - 06-08-2021
Going back to considering how a crankcase/block silicone gasket might be achieved with the engine in the car. I have not decided to have a go at this yet, but am trying to think though the process.
The "What have you done today with your Austin Seven?" thread has recently contained advice on how to loosen the less accessible of the seven block hold down nuts. The block would then be have to be lifted clear of the studs? And kept reasonably square? Then the surfaces to receive the gasket need to be assessed for flatness and cleaned? Then the gasket would have to be stretched into place having had all the internal links cut so it would go round the various obstructions. Has anyone tried this yet? Can it work, please?
RE: block to crankcase joint - external seal? - Hedd_Jones - 06-08-2021
Are you suggesting you
1. lift the block up a bit,
2. scratch off the old gasket (depositing most of it into the guts of the engine).
3. Realize the crankcase isn't flat, and isn't going to be flat without spending lots of money
4. Decide ''it'll do''
5. Stretch a new silicone gasket on it like a rubber band, having first damaged it by cutting it
6. Put the block back down.
7. Wang the nuts up and call it good?
Can it work? Yes.
Will it work? I'm not a betting man, but if I was, my money would be backing the horse called ''not a chance''.
RE: block to crankcase joint - external seal? - Colin Morgan - 06-08-2021
Thanks - that is a great answer.
Only other questions would be: Has anyone tried it? What happened?
RE: block to crankcase joint - external seal? - Chris KC - 06-08-2021
Colin, few of us can claim oil-tight block to crankcase joints even with everything set up sweetly on the bench... I most certainly can't.
RE: block to crankcase joint - external seal? - Colin Morgan - 06-08-2021
The silicone gasket does seem to offer the promise of a better seal here? It is worth exploring under what circumstances it might work? I suppose it depends how bad the joint is at the moment - the odd drip in the drip tray is not a problem.
With any given engine, there are a lot of variables - most of which are under control when the engine is fully dismantled - but it sounds like it would be a leap of faith with the engine in the car? To disturb all this and end up with more of a leak (and the potential for further damage) would not be clever.
RE: block to crankcase joint - external seal? - JonE - 06-08-2021
Wouldn't you need to cut the outside perimeter - as well as all the inner links - of the sheet silicone to get it round the conrods?
Would it not be better to do it with the tubed silicone product (recommended by others elsewhere) for a complete joint where it is additionally going to properly adhere to both faces?
RE: block to crankcase joint - external seal? - Howard Wright - 06-08-2021
Hi Colin
My old mum used to say “If a jobs worth doing it’s worth doing well first time”.
I’d bite the bullet and lift the engine out of the car. It’s not that much of a job.
Cheers
Howard
RE: block to crankcase joint - external seal? - Reckless Rat - 06-08-2021
It's much easier to work on the engine with it on the bench rather than in the car. Fitting a silicone gasket is dependant on clean mating surfaces. If not, then it will leak like any other. The engine on my RP used to leak oil like a sieve until it was rebuilt in 2019. It is now to all intents and purposes, oil tight.
ish
RE: block to crankcase joint - external seal? - Alan - 06-08-2021
It takes about 20 minutes to get the engine out and maybe an hour to put it back in, if you are in practice. Probably takes longer than that to work out a way to undo the back block stud, and then you have the conrods to undo from underneath or the pistons to ease back into the block. Honest guys taking the engine out is the easy solution