71 LeMans head freeze plug blew out

[Hazel]

Was cruising around Saturday morning, got on an open stretch of highway and opened her up...was awesome until BOOM, smoke everywhere! Lots of smoke. Turns out the freeze plug on the back of the right-side head completely blew out spewing antifreeze on the exhaust. When filling the radiator, I can see a stream of water just running out the back of the head.

My question is the fix. I found it hard to find info. Best I can tell, it needs a 15/16" or .938" plug. I found these that press in like the one that blew out but there's no room. Has anyone used the kind where you push in and turn the bolt to expand the rubber to seal it? I've found 7/8" - 1", ,then some a little bigger, some a little smaller.

Any help would be appreciated. I really don't want to have to pull the head to fix this.

Randy

 

[92 Sunbird LE]

Used a rubber plug once, it worked ok. Another option is hole saw a hole in the firewall to install one from from the interior.

You just need a socket , extension, and a hammer to install. Brass is best for a freeze plug, should be able to find the weird size at your local Napa.Some say to install the metal or brass ones with some kind of sealer around it.

You can fix the firewall with the cutout piece and goop for now till you have to take out the motor or heads for something.

Doug in P.R.

 

[cammerjeff]

I know you don't want to pull the head to repair the freeze plug, but it is the only way to properly repair it. I would only use the expandable plug as a temp repair to get the car home or to a repair shop. They do work as long as they are the correct size. But I would not trust them long term.

I would also use it if you were close to the date of an event you wanted to attend with the car. Otherwise take the time to pull the head and do it right. Just my opinion.

 

[Hazel]

Okay. There's about 4 inches between the firewall and the freeze plug. I created a "press" that sorta worked, but it went in a bit crooked. If anyone else is doing this, once it get's crooked, pull back out. You're fighting a losing battle. I tried it again, this time being more careful...not long enough. On my 3rd try, I took my 1/2" drive ratchet and used it like a hammer. I got about 3" to "swing" the hammer. Once I tapped to make sure it was going in straight, I beat it for about 2 hours to get it flush with the head. I know it's supposed to go in farther but I used a gasket compound that was drying as well. Anyway, I took it to a car show on Sunday and it held up fine. I didn't put the pedal to the floor like I did when it blew out, but I think it'll hold.

Addtl Info: The head casting, just inside the freeze plug hole, is very close. There is no way to use a rubber-type as it won't go in but maybe 3/8". The only other option is one of those all-brass deals from DORMAN with the nut on the outside...look super-sketchy and they don't even manufacture the 1 3/8" anymore. I found one but chose not to even try it.

As cammerjeff said, do it right with the plug. It's really the only option. If it pops again and have to pull the head...I'm putting new heads and cam in it. That damn $1 freeze plug will cost me a few grand but at least it'll have a little thump in the idle!