Topic: Bubbles from head stud, 21-Stud V8


Howie1935    -- 08-10-2026 @ 4:53 AM
  Coolant issue last year or more, losing about a gallon over 40 miles. Had heads surfaced and used 'Best' brand composite head gaskets.
I did not replace existing studs since no consensus on doing or not doing.

I have coolant and bubbles on one stud after first heat cycle. I have retorqued to 50 foot pounds but have not run again.
Question if still leaking up through the stud:
1. Pull head, and replace stud
2. Pull and replace all studs
3. Different gasket brand
4. Put thread sealant (Permatex #2) at base of stud at head

Thoughts?



marko39    -- 08-10-2026 @ 5:19 AM
  there is a good chance it will seal itself after a while. give it some time .


kubes40    -- 08-10-2026 @ 5:37 AM
  I'm with Marco. This is not uncommon at all. Nearly always it cures itself.
If it really bothers you, remove the head nut, pack some plumber's graphite packing string in there and replace the nut.

Mike "Kube" Kubarth

This message was edited by kubes40 on 8-10-26 @ 5:38 AM


carcrazy    -- 08-10-2026 @ 9:32 AM
  If you are losing a gallon of coolant after just driving 40 miles, I would be very worried that you either have leaking head gaskets or a cracked head or block. I am assuming that you didn't overfill the cooling system. Only put enough coolant into the radiator to have the level be about one inch above the top of the core. If you put more coolant than that in the system, it will just be pushed out of the radiator through the overflow tube during the natural heating and cooling cycles of the engine.

Things you can try to prevent the leaks are:
Remove the stud that is leaking and coat the threads that screw into the block with Permatex #2

If you are unable to stop the leaks by just using the correct amount of coolant and sealing the leaking stud, you may want to ad a bottle of Bar's Stop Leak to seal all of the coolant leaks in the system. This product uses rice hulls which will impregnate the leaks and seal them.


pauls39coupe    -- 08-10-2026 @ 10:33 AM
  We have had better luck with Felpro gaskets. Seal the studs to the block with a good thread sealer made for the job. Use K-seal in the water to seal minor leaks.
As others have said it may cure itself after several heat cycles.


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