Nobody seems to have a good word for using sealant on the O rings. I did mine with new viton rings last year and the right hand side has been totally dry. The left however leaks as bad as ever. Tom Wilson however recommends Permatex 3H or an RTV silicon sealer on the O rings so I might give it a go. Comments anybody?
The usual reason for avoiding using sealant is you have to clean it all off very thoroughly before fitting new pushrod tubes, or lumps of sealant will push the seals back and will tend to cause leaks. On a clean cylinder head it should not leak with only the proper seals, and just a smear of oil, and a little jiggle as the head goes down to centre the tubes (on a type 1) Did you stretch the pushrod tubes to the correct length again before re-installing ?
As Zedders has noticed, its a type 4 so that doesn't apply. I cleaned everything carefully and I've even since checked that the seams on the tubes are on top as Wilson recommends. I can see how sealant might make it difficult next time round though.
My builder used a smear of stuff called Wellseal. It sticks like **** to a blanket and left a ring of green o-ring stuck to the head when I finally managed to pry it free. If he'd used it seal/tube as well as seal/head I can't imagine it leaking ever again. Thinners and a plastic scraper got it off.
When I built my type 4 I used a smear of oil on new seals. The right hand set leaked straight away. I give them all a twist and that worked .
love the smell of wellseal use to use it when at the MOD I sure some of the fitters had it in their tea.
I used plain oil first time but the rubbish black rubber gaskets. Leaked. Then I used Hylomar and better viton gaskets. Still leaked and was a nightmare to clean up. Then I bought Permatex Aviation sealant on reccomendation from someone on here and viton gaskets and a little twist. Seems to be holding up OK...but I have another leak somewhere. Suspect its the dipstick boot. https://www.ebay.co.uk/itm/80019-Permatex-Aviation-Form-A-Gasket-No-3-Sealant-Liquid-/254414117464 I found Hylomar is more 'gummy' than the Permatex.
The crankcase, heads and the O-ring grooves in the tubes need to be scrupulously clean and all burrs removed, if there’s traces of old sealant or damage, they’ll leak whatever you do. I just use a smear of o-lube on the rings; but if you must use sealant, only use it on the crankcase end, the head end needs to be free to slide as the engine expands – not a lot but enough to cause a leak if the O-ring is gummed up with sealant.
