crank case to barrel leaks

How common are these leaks, they seem to have been an issue for 40 years, when I refitted my barrels 10000 miles ago they were refitted using a good quality silicone,no gasket, have been dry as a bone until yesterday, after 600km round trip on all types of roads, 30km of gravel and nice winding country roads( tennis raquet country) :shock: ,with 80mph sweeping corners, wasn't all good poured down for 1/4 hour wet arm pits and nuts for 2 1/2hours, talk about shrinkage need to carry extension tube just to clear jeans. Any way get home and it looks like the through bolt behind tach drive must have loosened,was hoping it was the tach drive but no.Happened to others has it, dont want to fit a gasket as i consider that even worse, may be a good anerobic sealant?

Nope. Never heard of it.

splatt said:

dont want to fit a gasket as i consider that even worse, may be a good anerobic sealant?

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From previous forum discussions* on the subject of anaerobic sealants, Loctite 518 appears to be what's recommended. http://www.loctite.co.uk/cps/rde/xchg/S ... 000000IVH6

*(I suggest you do a forum search, using the word "anaerobic" for more information?)

I've used Yamabond (Permatex Ultra Grey, etc.) with good results. Sir Mick Hemmings recommends Wellseal. Probably a lot of good products that would do the job. Silicone maybe not.

BrianK said:

I've used Yamabond (Permatex Ultra Grey, etc.) with good results. Sir Mick Hemmings recommends Wellseal. Probably a lot of good products that would do the job. Silicone maybe not.

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Permatex Ultra Grey is an RTV silicone, I don't know about the Yamabond.

Yamabond's a different brand of the same basic stuff. May be silicone, but it doesn't set up like it. Much better for this application, I think. FWIW/YMMV.

I believe Yamabond is a re-brand of Threebond 1104, which is a synthetic rubber (non-silicone) and a semi-drying system and similar to Hylomar. I'm not 100% sure as I have never actually had a tube of Yamabond, so I'm just going by the datasheet.

Wellseal has worked er....'well' for me; my T140 suffered from loosening of the barrel flange nuts after its last rebuild (some prat forgot to re-torque them after 50 miles ), and it looked a real oily mess, but after nipping everything up the barrels re-sealed themselves fine with no leaks since - I was both suprised and relieved.
I don't know any other sealant which would do this. Previously I've used Hylomar with good results, but it wouldn't have tolerated this sort of abuse.