What's a good headgasket for sealing leaks

[Chester C.]

A 65 I'm working on has a small head gasket leak. Owner said he replaced it with a felpro but does not remember number. Is there a head gasket that is soft enough to seal water leaks. It's a high HP engine.

[Edward J.]

Re: What's a good headgasket for sealing leaks

Chet,'
Try re-torqueing the head (s). Maybe through the heating and cooling cycles they may have loss some torque.

[Dan B.]

Re: What's a good headgasket for sealing leaks

Had a chevy smalll block that ran fine, but was tired. I rebuilt it through a reliable machine shop and the motor ran strong, but had a coolant leak at the head gasket now, you could see the coolant weeping. Machine shop said it was probably a sand casting pit and to try some Bahr's stop leak , ( I was thinking this was a dodge) it took 2 treatments to stop the leak totally and that was a great running motor for the remaining time I owned it. My understanding is this was routine practice on the assembly line. Certainly check torque first as suggested. Dan

[Thomas H.]

Re: What's a good headgasket for sealing leaks

I've always had good success using the Felpro Perma Torque gaskets. Make sure the mating surfaces are clean before assy.
If he replaced the gasket it is possible that there was some debris left on the mating surfaces.

Also make sure you use a good sealer on the head bolt threads.

If you have the heads off can you see where the leak is coming from? Put a straight edge across the head in several spots checking clearance with a feeler gauge. You can do the same with the cylinder deck.

When using the steel shim gaskets a good coating of permatex copper spray will help seal also.

Tom

[Jim D.]

Re: What's a good headgasket for sealing leaks

Good advice posted above. Re-torque the heads and add some stop leak. https://barsleaks.com/product/head-gasket-fix/
You have nothing to lose by trying it.

[Terry M.]

Re: What's a good headgasket for sealing leaks

Dan is right about a leak deterrent product being used on most/all new cars. While I hate that stuff (It makes a mess inside the coolant system, and I can't imagine it helps heat transfer), most OEMs now days use it to prevent minor seepage that causes warranty claims.

[Jim T.]

Re: What's a good headgasket for sealing leaks

Terry my 1996 Corvette LT4 was bought new. The owners manual stipulates to use GM Engine Supplement (sealer) (GM Part No. 3634621) with any complete coolant change. I have down this with every coolant change every five years using DEX-COOL antifreeze.
The supplement from GM is the same as what BARS sells in tablet form. So far no coolant problems or leaks in 21 years.

[Chester C.]

Re: What's a good headgasket for sealing leaks

The guy he purchased the car from said it had a dewitts radiator and dewitts stated any stop leak will void the warranty. Radiator in car is to old for warranty anyway but interesting they should state that

[Jim D.]

Re: What's a good headgasket for sealing leaks

The guy he purchased the car from said it had a dewitts radiator and dewitts stated any stop leak will void the warranty. Radiator in car is to old for warranty anyway but interesting they should state that

I've purchased several rads. from Tom DeWitt and don't remember ever seeing that statement on any warranty. The current lifetime warranty makes no mention of stop leak.