Primary chain case gaskets

[jhg1958]

The last time I put the chain case cover on I put my favourite sealant hylomar with the gasket. It was oil tight!  On taking it off the gasket was damaged and I spent ages cleaning up the surfaces.

I know some people put grease on gaskets with great success. I had an idea of putting grease on the inner and hylomer on the outer thus getting the benefit of the flexible sealant and letting the gasket come away when opened.

Is this a stupid idea?

John

[berger]

not stupid at all but you might find the hylomar creeps and causes sticky unexpected problems on the next removal , i'v tried it.

[sean]

I remember back in the 60s using red Hermetite and thick cotton thread for case gaskets

[berger]

yes sean i used to borrow tins of red from the coal board stores i was fed up when i opened up an untouched one after 30 years and it was bin time , green i used on blowing cylinder head pipes it was made for steam joints , rate good.

[Swarfcut]

 Hermetite Red used alcohol as a solvent, so mating faces can be cleaned up with old fashioned meths if you can get it. Steel wool, elbow grease and a slug of meths does it without damage for the last remnants.

 Hylomar is cellulose thinners/xylene based so again to take your chance inhaling this vapour, same as you did backyard paint spraying.

 Grease on gaskets ensures parts come apart, but the joint may not be fully oil tight. Good flat faces, jointing compound and adequate clamping force does the job. Make sure blind holes don't have debris at the end...bolts bottoming on this before the joint is fully clamped is a sure recipe for a leak.

 Swarfy.

[Colsbeeza]

Another thing is when you do up the chaincase screws, I remove the rear chaincase bolt and then refit it after the screws are tight. This ensures that the covers can bend a fraction to ensure the gasket is clamped evenly. You can then be sure that the spacers (washers between the chaincase lug and frame} are correct and will not put strain on the chaincase.
Col

[muskrat]

G'day John.
I use Permatex Aviation #3 on most gaskets (I make my own). 90% of the time the parts come apart and the gasket is reusable. https://tinyurl.com/2c9onntb
Cheers

[BagONails]

There's a guy on YouTube , professional classic mechanic, not a satanic mechanic as far as I know, . He swears by Stag Wellseal for pretty much every gasketing job. I've not tried it but by appearance and consistency it looks very much like the Permatex Aviation non-setting goo that Musky uses and I have had a lot of luck with (except those pesky rocker boxes but I don't think it matters what you use on those buggers!) Loctite No3 is also similar.

The one I am hoping will do the trick and I have used on the A65 for all non-maintenance ie. semi-permanent joints is Threebond 1215 which I think is Japanese and sold by various OEM's under their own names i.e. Yamabond! It is good but not if you want to disassemble and reuse the gasket.  Anyway thus far NO LEAKS!

[BSA500]

No gasket and wellseal got fed up with replacing the gasket everytime I had the chaincase off. Doesnt leak

[Slymo]

I use 0.8mm Flexoid and no sealant at all. It needs a couple of retightens but then settles down to be a reusable and leak free gasket ( at least it doesn't leak from that particular pair of mating faces) 

[fffcycles]

I worked on a crew doing electrical work and startups on Stal Laval steam turbines. The factory mechanic Bjorn ( of course a monster of a fellow) would recruit all and sundry in taking rolls of Teflon tape and twisting them into long strings he used on all large flat joints. Never saw anything leak that he put together. Still sometimes use this strategy on large difficult services

[Nourish]

Watching Mick Hemmings on his Norton engine build DVD - he used to use Wellseal on the crankcases and left it overnight before assembly.

[jhg1958]

Thought I would follow up on this. No sealant just a thin film of grease seems to have done the trick.

No oil leaks (up to now)

John

[Colsbeeza]

Hi John, I have used Hylomar or Hermetite on the outer and Lithium grease on the inner, hopefully to be able to reuse the gasket. It was a good seal but I could not save the gaskets. The gasket got a bit floppy upon removal and I suspect that oil or grease soaked through the gasket and softened the adhesive, which pulled off the outer chaincase fairly easily. I now use grease on both sides and do not try to save the gasket. But I do cut my own from 0.8 gasket paper so not too expensive.
Col