Manifold gasket replacement

[Quentin_D]

Hi all,

I have an exhaust leak between my block and the manifold around one of the studs.

I tried to tighten the nut of the stud but the stud is so corroded that I just destroyed the thread. I couldn't remove the stud with the stud removal tool as there is almost no thread left and the stud is too short anyway...
Then I have to remove the exhaust manifold and I will install the new studs I just received.

Do you know what kind of permatex I have to put on the studs going into the block ?

Thanks

[Tim]

I tried permatex #2 on the head and exhaust studs on my rebuild, but at least half of them were leaking when I pressure tested the engine. On advice from Ken and Don, I cleaned off the gasket sealer and reinstalled the studs using red Loctite, no more leaks.

[Marty Levenson]

sealant

Hey Tim - Was there something special about your install? I have always understood that permatex _ not sure which one - was there for a gooey air and water tight seal....?

[Al Schober]

Come on folks, you know better! Permatex is a trade name, not a product. They make everything from silicone sealants to thread lock compounds - and more.
I like JB Weld for installing studs.

[Tim]

Al, you are right, Permatex makes both the #2 gasket sealant and Loctite.

Marty, there didn't seem to be anything unusual about the rebuild or the head installation. I did some research on Permatex's website after the studs were leaking. The none of the gasket sealers are recommended for thread sealing. The Loctite tech. sheet stated that it locks AND seals threads. I ended up using red Loctite on the head studs, manifold studs and the water jacket cover studs with no leaks.

[Quentin_D]

Hi all,

Finally I used Permatex Aviation #3 as suggested in my old Moyer manual.
Thanks Marty for providing it !

I re-assembled the parts all together but I got a very bad surprise.
The thread in the block where the exhaust leak was coming from just broke up. I didn't tight it that much tough.

Then, what to do now ? Any suggestion ?
Any temporary fix to go sailing this summer ? Or it is worth fixing it right now for good ? How to do that ?

Thanks for your suggestions ! My C&C want to go sailing !

[edwardc]

This is a very common problem. MMI sells a repair stud kit for this. It consists of a special stud with a larger thread diameter on the block end, and a tap to tap out the block to the bigger size.

The alternative is to drill and tap the block to accept a threaded repair bushing that restores the original thread size. The repair bushing is similar to a helicoil, but it is a solid piece because a helicoil is more likely to leak in this application.


Stud repair kit: MMI OBLK_06_446


Repair Bushing: MMI OBLK_09_114

[Marty Levenson]

choice?

Hey Edward - what are the advantages/disadvantages of repair bushing vs old school drill and tap?

Thanks!

[Quentin_D]

Thanks for the quick reply Edward !

As Marty asked, what are the pros and cons of the two approaches ? Maybe it has been discussed many times in this forum.
I guess that the using the repair stud is more robust.

I have something that looks like this repair kit in my boat from the previous (or previous previous) owner.
Otherwise Marty just told me he has it !

[edwardc]

Because the repair stud has a larger diameter at the lower end, it won't fit thru an unmodified head. You either have to install it before the head, or drill out the head slightly. The repair bushing allows you to use a standard stud.

[Quentin_D]

Thanks all !

My Atomic 4 is now running pretty well !

Let's go sailing !