Head Stud Sealer

If you are talking about screwing the studs in the block, I use a plumbing product, teflon pipe dope(not the tape).
 
I have not had good results with the white teflon paste products. Aviation Permatex has worked best for me.
 
Five replies and five different opinions. Funny, it would have seemed strange to me if they were all the same! :)
 
Steve, if you can find Tite Seal medium Part # t25-66 you will be amazed at how good it is. A 1 lb can will last about 200 yrs. We used it on all kinds of joints and threads on submarines and it was great stuff. Check at a plumbing supply house.
Don
 
Permatex is a good product.
But, be careful that you don't electronically isolate your heads from motor ground.
When I brought my 39 home (drove it), it was running very poorly and would not maintain 20 mph up hill.
We stopped at the half way point (25 miles) for gas and I checked for the obvious.
First thing that I found was that the AC plugs were not seated and a few plugs were no more than finger tight.
I cleaned and gapped the plugs (later replaced with correct Autolite 216L) and the truck seemed to pull somewhat better.
When I got it home I decided to have a look under the hood -after dark.
What I found amazed me.
There was an electrical arc running around the end of the studs to the nuts holding the heads down.
Each head showed 2 or 3 studs with glowing coronas dancing around the stud to nut transition.
The engine is a very fresh rebuild and the builder made use of every trick in the book to seal the heads.
Gooping the studs and using fiber gaskets physically isolated the head from receiving the ground that the spark plugs required. The spark plugs were firing but were not transmitting the coils full potential to the tang on the plug (the ground). This weak spark was responsible for the very poor performance of this fresh rebuilt.
As a result, the new engine has never been properly broken in and the oil was somewhat diluted with excess hydrocarbons (partially spent gasoline).

The prior owner had trailered this truck to car shows and the only time it ran was when it was put on the trailer. The truck was very under powered to say the least.
It was an easy fix though, I simply ran a ground strap to each head from a stud on the back of the block/intake. That's not the proper way to do things but it saves pulling the heads and studs out of a brand new rebuilt when a guy doesn't have to.

Unfortunately, my work schedule is horrendous and the truck has been garaged since I brought it home. I have on occasion started it up just to bring the temps up and I will usually let it run for a couple of hours once it is up to operating temperature. I have been varying the idle to help get this engine broken in. Although this is not the best way to break an engine in, it sure has helped clear up the cold and rich idle that the truck started out with. -Cold as in the engine never physically made enough heat to come up to temperature while driving or idling as most of the gas going thru the carb was exiting the tailpipe. This engine never had a chance to make horse power or heat. It has also been a real bear to get started.


When I first discovered the dancing arcs on the cylinder head studs I was amazed and a little bewildered, electricity does funny things. We all know what a poor ground does to tail/headlights and after seeing this it now makes sense that using all the tricks to bolt our heads down can also isolate them from receiving a proper ground, a ground that the spark plugs absolutely need in order to fire to their full potential.

I have always been in favor of gooping up the studs but will now pay close attention to the holes that do not really need to be sealed as a result of being to close to a water jacket. Some holes/studs might be better off with a little coppercoat and holes that are closer to the water jacket can take on some aviation form-a-gasket (permatex). Coppercoat, unlike form-a-gasket, will promote a proper ground.

jmho

moe


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Russ/40 said:
I have not had good results with the white teflon paste products. Aviation Permatex has worked best for me.
Click to expand...
Being a plumber I have used the teflon pipe dope on all the engines I build and have had ZERO problems with leaks. Maybe there are different grades of the product. I buy mine at my plumbing supply house.
 
flatjack9 said:
Being a plumber I have used the teflon pipe dope on all the engines I build and have had ZERO problems with leaks. Maybe there are different grades of the product. I buy mine at my plumbing supply house.
Click to expand...

I used the "Loctite Thread Sealant With PTFE" Did not work as well as the Aviation Permatex. The plumbing stuff must be better.
 
when you change or rebuilb an eng you schould fill the cooling system with water for several reasons 1-if you have a leak you don,t have to recapture the coolent 2-any reduse left in the system will be cleaned out when you drain the water & add the anti freez 3- the water will will carrey rust to the studs thus sealing them.they may leak for a while but they will seal them self,s. 4- if you have a runing hot proulbem you can correct it whith out spending money on lost anti freez plus if it gets into the eng it can caust more proulbems when eng is runing right drain water & add anti freez if you are in a cold cilmet & must use anti freez from the get go i use indean head gasket sealer.
 
The consensus seems to be for a Permatex product. There's a vote for Permatex #3, and Permatex #1. Any discussion on the merits vs disadvantages of those two?

Bob
 
I use Prematex #2 it is non hardening. My theory is that the non harding will flow to the area with least pressure (leak) vs hardening becoming ridged. As well hardening does not respond to heating and cooling....ie...expansion and contraction......my 2 cents.
 
"We used it on all kinds of joints and threads on submarines and it was great stuff."

Did you use it on the SSBN-632? Thats the boat I qualified on in 1968.
 
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