The Stovebolt Site Forums The Shop Area Engine Shop 235 expansion/freeze plug help

Hey all,

Well I just replaced the two expansion plugs on the intake/exhaust side of the block with new brass ones and they both leaked on me. I put them in dry and seated them about a sixteenth into the casting.

I pulled them out today and am going to try it again. This time i'm going to really clean the machined surface well with emery (probably 600 grit) and but some sealant on them.

I'm thinking of using Permatex Aviation Sealant but am open to a different type that others on the board have used with success.

If you go the sealant route, is there a prefered type for this application?

I really don't want to do this again!

Really clean the block, rotary wire brush works well, it should be shinny, clean metal.

I like to use Permatex® Aviation Form-A-Gasket® No. 3 Sealant Liquid , This stuff never really drys and seals really good.

Joe

RTV is good for that.

Permatex #2, or Indian Head sealant works well too.

Thanks everybody, I'm gonna go with some sealant this time for sure.

Also, I purchased a installer kit instead of using a socket to drive them home. I used a 1 1/8 socket for the 1 5/8 plugs. It fit just inside the lip, and read many posts where people had no issue with this.

I did find a few articles that stated these plugs are better tapped in using the tool that applies the force on the rim of the cup, instead of the inner edges around the rim like the large socket does.

I'll be taking the carb, intake, and headers off the engine again tomorrow and take a good look at the holes to make sure they are as clean as I can get them before I drive the new ones home.

Well just an update, I reinstalled the freeze plugs with some Permatex Aviation sealant.

They both weeped a bit but much less. After a couple of heat cycles the rear plug near the throttle pivot sealed itself.

The front plug is still weeping ever so slightly. I am gonna let it head cycle a few more times and if it doesn't seal itself will probably try some Bar's Leaks radiator stop leak tablets. It says 2 tablets per galloon so I was planning on putting in 8.

Their website says the are harmless to your system and can seal minor leaks. They also say many OEM companies sell them and also put them in new car coolant systems at the factory.

Anybody had bad good or bad luck with these tablets?

Just ran her again, and looks like that front freeze plug sealed up, i'm keeping my fingers crossed but no seepage or leaks this time.