Packard Forum Index » V-8 (1955-56)

I just finished repairing all the oil leaks on the engine and while I was under the car I noticed a freeze plug that had just started leaking. It's the one under the motor mount so I was planning on pulling the engine to get at it. Packard V-8 said it can be replaced without pulling the engine, just remove the motor mount, so I will give it a try. If frustration gets the best of me then I will pull the engine. My thinking is that if one is leaking the rest will be leaking soon so replace them all at once while the antifreeze is drained. Any comments on that theory? Are there any "tricks of the trade" to pull a freeze plug and installing a new one? I was gonna drill a hole in the center and pry it out then clean the surface area of the block then tap a new plug in. Are there any sealants I should use? Thanks in advance for advice and comments. Brian

If one core plug has begun to corrode thru and leak and they are all of the same vintage, the others won't be far behind. I use Permatex Aviation grade, the hardening variety. Simple old gasket shellac is a good alternative. I've replaced plenty of them on the in-line 8s, never had occasion to do one on a V8 in the car, so no advice there.

Since I don't know the history of the freeze plugs, I'm going to replace them all and be done with it. You mentioned using hardening permatex on the plugs, wouldn't that prevent the plugs from moving in the event of a freeze?

Freeze plug is a common misnomer. They are core plugs or welch plugs. They have absolutely nothing to do what so ever with a freezing block. They are there for foundry manufacturing purposes. It allows the foundery to clear the newly cast block of sand core.

My personal judgement and based on my experience is to only replace such plugs as necessary, meaning when one is found to leak. I can't remeber if there is one at the back of the block or not that mite require removal of trans to replace.

There is a freeze plug at the rear of the block that requires the removal of the fly wheel or flex plate. It actually acts as an oil plug for the cam shaft. If it leaks, it is oil not water.

Some good tips on removing core plugs in the current edition of "Skinned Knuckles", Issue 436, November 2012. Same issue also has a good article on headlamps from the mid-30s thru the 90s and another good one on valve train and other engine noises with good focus on flathead engines.