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Best Silicone or JB Weld for Engine

1987 Integra, 146k

There is a tiny valve, 1 mm diameter, related to bleeding coolant - coolant is leaking there.

Its in the corner of the Engine, so it can get hot.

A friend said get a Silicone to seal it off - called Kragen - they said not Silicone, but JB Weld.

Any recommendations?

Also what temp engine block gets to ?

Maybe 2 hot for jb weld
The trick for any sealer is to make sure you give it PLENTY of time to set up.

JB-Weld will work if you do it right…Surfaces must be spotless, allow 48 hours undisturbed to cure. Just when you think it’s clean enough, clean it again with MEK or acetone…

JB Weld can be used up to 500F. Some (not all) silicones can be used up to 600F, though 450F to 500F is more usual. Some high temperature silicones need higher temperature to cure, too.

Fixing the problem right is not a option?

This is the coolant system bleed valve so air can be removed from the cooling system.

It just might be this bleed valve is defective, And a replacement with a little pipe joint tape/compound will fix the problem. Instead of doing the Mickey Mouse fix?


My recommendation is fix it right and forget the goop 'em.
Weigh the price of JB Weld against the cost of a lost engine.

If it’s corroded and replacement is impossible, drill it out and tap it to 1/8" pipe threads and put a brass plug in the fine hole you just made…In an aluminum head, this should be quite simple.