Big block coolant leak out lower head bolt

[William H.]

I have a 1968 big block L-89 engine that I had to pull the driver side head off of. There was a pin hole leak in the exhaust port which we welded. When I re-installed the head, I have coolant leaking out the 3rd bolt back from the front on the lower side (short bolt under exhaust manifold). It's a small drip type leak. I understand the four lower short bolts go through the water jackets. I used permitex thread sealant on the threads and black RTV on the bolt shafts when I installed and torqued. The three other bolts seem good and dry. There was still a little water in the hole when I installed because I was not able to drain fully from the radiator. Any suggestions other than block sealant? Thanks for your expertise.

[Dick W.]

Re: Big block coolant leak out lower head bolt

Are you sure there is not a crack? Loctite (Permatex) pipe sealant with teflon almost always seals any leaks.

[William H.]

Re: Big block coolant leak out lower head bolt

Dick. I am almost positive it is coming up through the bolt. I used permatex thread sealer but not locktite. There was also water in the bolt hole when I installed so I did not know if that could have caused the problem. Thank you for a suggestion. Bill

[Dick W.]

Re: Big block coolant leak out lower head bolt

Dick. I am almost positive it is coming up through the bolt. I used permatex thread sealer but not locktite. There was also water in the bolt hole when I installed so I did not know if that could have caused the problem. Thank you for a suggestion. Bill

Bill Loctite and Permatex are one and the same, Loctite owns Permatex.

[Michael G.]

Re: Big block coolant leak out lower head bolt

Bill Loctite and Permatex are one and the same, Loctite owns Permatex.

Both name brands may be owned my the same corporation Dick but are two different products with their own unique application.

[Joe L.]

Re: Big block coolant leak out lower head bolt

Dick. I am almost positive it is coming up through the bolt. I used permatex thread sealer but not locktite. There was also water in the bolt hole when I installed so I did not know if that could have caused the problem. Thank you for a suggestion. Bill

Bill------


If you use any type of good sealer that should prevent any coolant from coming up the bolt threads. I prefer Locktite Pipe Thread Sealer with Teflon. However, as I say, any good sealer should do the trick. If it does not, I would say there's some other problem.

[Domenic T.]

Re: Big block coolant leak out lower head bolt

Bill I have seen that happen before. When you go to reseal it I wound sugest draining the block on that side and drying the threads with air before re-sealing the bolt. All the head bolts enter the water jacket.

DOM

[Joe L.]

Re: Big block coolant leak out lower head bolt

Bill I have seen that happen before. When you go to reseal it I wound sugest draining the block on that side and drying the threads with air before re-sealing the bolt. All the head bolts enter the water jacket.

DOM

DOM and Bill-----


Whenever sealant is used on a threaded system, the threads MUST be scrupulously clean and dry. If not, the chances that the sealer is going to be effective is about 50-50, or less.

[Dick W.]

Re: Big block coolant leak out lower head bolt

Both name brands may be owned my the same corporation Dick but are two different products with their own unique application.

Michael, I have both Loctite PST and Permatex pipe sealant with teflon in my tool box. Appear to be the same product

[Ronald L.]

Re: Big block coolant leak out lower head bolt

Loctite is a brand, depending upon the type, if it is cyano acrylate, it fails with moisture...if wet going in, it has high probability to not cure properly and not seal.
Make sure its dry as a bone.