cylinder to down pipe gasket sealer

[lam1962brettagg]

just wondered if anyone has used this copper heat resistant up to 350 degrees silicone gasket seal on a downpipe and if so is it anygood?
cheers

[ULC Soulagent]

Yes and it’s rubbish

[bennn]

I've also used it and it had mixed results, sometimes seals - sometimes not.

Only used it on 'slip joints' to try and stop oil etc leaking out, anyone know of anything better?

[lam1962brettagg]

thanks for input, thought as much but thought I would throw it out there for a kick about.

[Warkton Tornado No.1]

I use it only when necessary for head to cylinder sealing. Spigotting is the best sealing method & the process centralises them too, but that's not always practicable.

However, I agree that the stuff is not good for the exhaust seal.

Silicone bathroom sealant (smells like vinegar) has never failed in over 20 years.

[Ken Tucky]

Another vote for silicon sealant, and its cheap and readily available.
I too have used it for years (clear), a lot of years, on my sprinter........so its not road use, with methanol btw..............seems to work........lol
Mr Tucky

[lam1962brettagg]

thanks for the post Ken, looking like the sealant to use is the one everyone is mentioning. not the copper one I asked about.
cheers

[Danbretta]

I've used that same copper sealant, both times its ended up blowing out at the manifold flange. I'm going to use the bathroom sealant (as warkton has suggested) when I get around to putting the exhaust back on.

[bennn]

Looks like I'll be joining the bathroom silicone club too!

Thanks lads, Ben.

[lam1962brettagg]

I use it only when necessary for head to cylinder sealing. Spigotting is the best sealing method & the process centralises them too, but that's not always practicable.

However, I agree that the stuff is not good for the exhaust seal.

Silicone bathroom sealant (smells like vinegar) has never failed in over 20 years.

spot on mate! used the silicone you suggested, not a spot of oil in site, nice light brown electride on plug now instead of black oily.
really appreciate your advice.

[Wombat67]

Dumb question time - I'm assuming this is instead of, not as well as the copper exhaust gasket? (i've got a blown gasket to fix at the weekend so this thread is perfectly timed ) Thanks

[lam1962brettagg]

Dumb question time - I'm assuming this is instead of, not as well as the copper exhaust gasket? (i've got a blown gasket to fix at the weekend so this thread is perfectly timed ) Thanks

Hi,
solid copper gasket(not the cheap nasty copper ones in gasket sets)
Plus sealant (port side of gasket very sparingly!) Then when gasket in place offer up the down pipe with sealant applied to the gadket face of downpipe. I also used it on the downpipe to exhaust joint.
not a sign of a leak now.
hope that helps.
note! if you put the sealant on the port side(which I did) put it as near and as thinly as you can to the edge of the gasket to avoid surplus accidentally obscuring the port.
LEAVE FOR 24 HOURS TO CURE BEFORE STARTING THE ENGINE
the sealant will give of a little steam/smoke to begin with but soon disapears.
Forgot to mention, dry fit the gasket and downpipe first and use a phonetorch to make sure it is a good flat fit.
my cylinder exhaust port RT195 had a slight ridge that had to be removed to allow the solid copper gasket to sit perfectly flat on the port. removed it with a dremel or similar.
its also a good idea to get a helping hand made it alot easier.
cheers

[Wombat67]

Thanks

[Warkton Tornado No.1]

Dumb question time - I'm assuming this is instead of, not as well as the copper exhaust gasket? (i've got a blown gasket to fix at the weekend so this thread is perfectly timed ) Thanks

Needs must & all that.....When racing, there is hardly ever the luxury of spare time. So the bathroom silicone sealant is literally spread on to the (very! Use Meths or a solvent) clean faces & the fasteners tightened up & lockwired.

That's it, with no time to allow cure or removal of excess.

Often, a grubby looking oval ring of snot will get blasted from the tailpipe. That will be the excess removed nicely

Put simply, it seals brilliantly, but cannot allow for fasteners coming loose. Therefore, I just find it easier to always lockwire pre-drilled longer nuts (10 mm across flats hexagonal extension nuts created from M6 with an M7 tap run through from Toolstation) with thick, hard, plain washers. This modification is one of the best you can do to a Lambretta. Even better than whip aerials, fox tails & disc brake windows

No need for a gasket (which as said previously) must be solid copper if using one. I only continue to use a gasket as it is the best way of matching the port to the flange.

I have dispensed with the gasket on occasion (Ha! When trying to obtain a Nat's more ground clearance ) & the bathroom silicone sealant works just as well.

[lam1962brettagg]

Dumb question time - I'm assuming this is instead of, not as well as the copper exhaust gasket? (i've got a blown gasket to fix at the weekend so this thread is perfectly timed ) Thanks

Needs must & all that.....When racing, there is hardly ever the luxury of spare time. So the bathroom silicone sealant is literally spread on to the (very! Use Meths or a solvent) clean faces & the fasteners tightened up & lockwired.

That's it, with no time to allow cure or removal of excess.

Often, a grubby looking oval ring of snot will get blasted from the tailpipe. That will be the excess removed nicely

Put simply, it seals brilliantly, but cannot allow for fasteners coming loose. Therefore, I just find it easier to always lockwire pre-drilled longer nuts (10 mm across flats hexagonal extension nuts created from M6 with an M7 tap run through from Toolstation) with thick, hard, plain washers. This modification is one of the best you can do to a Lambretta. Even better than whip aerials, fox tails & disc brake windows

No need for a gasket (which as said previously) must be solid copper if using one. I only continue to use a gasket as it is the best way of matching the port to the flange.

I have dispensed with the gasket on occasion (Ha! When trying to obtain a Nat's more ground clearance ) & the bathroom silicone sealant works just as well.

yes all relevant for racing, but for those who bimble around with whip aerials and such like great, And I do use the wire lock nuts too!

[Warkton Tornado No.1]

yes all relevant for racing, but for those who bimble around with whip aerials and such like great, And I do use the wire lock nuts too!

I think we are singing from the same hymn sheet .

I only wanted to convey that the stuff cures by heat so there is no issue with how soon you can restart your engine, regardless of it being for racing or a road scoot broken down @ the side of a busy road

Similarly, the excess will find it's way out with no risk of danger to engine internals. I have used it on inlet & base sealing faces. All joints on a (several) part construction exhaust are best sealed with the stuff, such as sprung slip joints, mufflers etc.