440 exhaust manifold head stud keeps leaking

[Sonny]

I’ve put Teflon pipe thread sealer (paste type) on this stud twice and it works for two weeks and leaks again. What should I use to stop the leak? The other seven don’t leak at all. Of course it’s the number 7 cylinder with the 2” stud/nut in the hp manifold

 

[moparedtn]

I dunno if it's the best, but it has always worked for me:

 

[Paul Secoy]

The last one I did I drained below that level, cleaned/dried the hole out as best I could, and used Permatex Ultra Copper silicone. Never leaked a bit. Good luck.

 

[Sonny]

I dunno if it's the best, but it has always worked for me:

View attachment 874670

Yep. That’s what I used.

 

[1967coronet]

Napa sells a small 1/2 pint can of hydraulic pipe thread sealer it is not teflon base.
Works at high or low temps and high pressure, I am pretty sure its a lead or metal base.
anyway, if you just can not get something to seal you may want to ck on that sealer.
If I get out to the shop later I will add a napa part number on here.

 

[moparedtn]

Yep. That’s what I used.

You can always use the tape, followed by the sealer.
Sounds like there's a bit of excessive gap between stud and hole?

 

[Paul Secoy]

I do let mine dry overnight before refilling the coolant, I'm not sure if you are or not. I have heard of others struggle with the same leak.

 

[Sonny]

I do let mine dry overnight before refilling the coolant, I'm not sure if you are or not. I have heard of others struggle with the same leak.

I’m assuming since that is the heaviest part of the driver side hp manifold it probably shakes the stud the most.

 

[khryslerkid]

Wish I had a dollar for every thread on this...

 

[Sonny]

Wish I had a dollar for every thread on this...

View attachment 874785

Thanks! Misery loves company.

 

[1967coronet]

I’ve put Teflon pipe thread sealer (paste type) on this stud twice and it works for two weeks and leaks again. What should I use to stop the leak? The other seven don’t leak at all. Of course it’s the number 7 cylinder with the 2” stud/nut in the hp manifold

here is that napa stuff, back side says it contains lead.

 

[moparedtn]

Wish I had a dollar for every thread on this...

View attachment 874785

Is that the "blue"? Good stuff, yep. I like the copper as well.
Honestly, I use the "pipe dope" Teflon stuff because I have a ton of it (we "tape n dope" all threaded
connections in fire sprinkler world).

 

[khryslerkid]

Is that the "blue"? Good stuff, yep. I like the copper as well.

This stuff has been around for many years. I remember my Dad useing it before I even had a clue about working on cars.

It's dark brown in color and has a strong smell to it. It has to be a oil base and it never hardens. It will get really stiff but remains somewhat pliable. I've removed header bolts, water pump bolts and the like that I had used it on months ago and it was still soft enough to reinstall and make a good seal.

I've removed leaking manifold and water pump bolts, applied it right on the threads, installed the bolt and it stopped the leak. Never drained the system. It reminds me of the old pipe dope, acts the same, smells bad. Don't get it on your fingers, you'll need gasoline to remove it.

It's not a silicone by any means. Silicone is for rain gutters.

 

[moparedtn]

This stuff has been around for many years. I remember my Dad useing it before I even had a clue about working on cars.
It's dark brown in color and has a strong smell to it. It has to be a oil base and it never hardens. It will get really stiff but remains somewhat pliable. I've removed header bolts, water pump bolts and the like that I had used it on months ago and it was still soft enough to reinstall and make a good seal.
I've removed leaking manifold and water pump bolts, applied it right on the threads, installed the bolt and it stopped the leak. Never drained the system. It reminds me of the old pipe dope, acts the same, smells bad. Don't get it on your fingers, you'll need gasoline to remove it.
It's not a silicone by any means. Silicone is for rain gutters.

Ah, from olden days Permatex. #1 and #2.
One hardened, the other didn't. Depended on whether you were concerned with future disassembly.
Both brown, smelled all to hell.
They were fine in their day - and probably still are.
Now - blue for water seals, red for high temp gaskets, copper if you REALLY wanna get after it and thread seal
for threads is the Permatex way.
Works for me.

 

[MoparGuy68]

I cleaned the dirt out of my exhaust manifold stud holes with a chaser/cleaner tap. The dirt buildup inside is what was keeping the header bolts that were in there from leaking.

Now I need a sealant to put on my studs or they will leak badly. I put 4 studs, two in each head (first and last position) in anticipation of running headers about a month ago. I used the Permatex High Temperature Thread Sealant. This stuff is rated to 400 degrees F, which actually doesn't seem like a very high temperature to me. My toaster oven can get hotter than that.

I needed to pull 3 of them out, to replace with longer length studs, because I now have to run HP manifolds instead of headers.

After being in there for a month, with the cooling system partially drained, this is what they look like. When I pulled them out the sealant was moist to the touch when I ran my fingers over it. I could wipe it off with my fingers. I'd describe it as clumpy. Isn't the sealant supposed to harden after 72 hours?? The studs were in there for a month!

I removed 2.5 gallons of coolant from the system, before installing these studs, along with making sure the coolant level was low enough in the heads so none would leak out if all stud holes were left open.

I want to make sure this is going to work, or if I should be using some other kind of sealant.. To the guys who have used this Permatex sealant, is this what the sealant should look like and be like after a month inside the heads?