freeze plug repair questions.

[Chris H.]

Discovered last night that a freeze plug on my L78 is leaking. I plan to drain the block (radiator unecessary?) and puncture the plug with a screw driver and pry it out. Replace with new one and perhaps use some sort of sealer. Does this sound correct or is there a different, better way to repair? How about plug availabilty and cost? Thanks in advance. Chris

[Joe L.]

Re: freeze plug repair questions.

Chris-----

Your approach sounds generally ok. However, I'd do the following:

1) You can just drain from the block drains until coolant stops flowing. Then, you know that the coolant level will be below the freeze plug level and that's all you need;

2) You will not be able to puncture the freeze plug with a screw driver; they are much too thick for that. However, you can drill a hole and use a slide hammer to extract the failed freeze plug. Also, after drilling a hole in the freeze plug, you might be able to remove it by prying with a small crow bar or similar tool. However, if it were me, I'd prefer the "straight-out" removal using a slide hammer.

3) You should use sealer on the new freeze plug. I recommend Indian Head, non-hardening Permatex, or RTV silicone.

4) Freeze plugs are readily available in any auto parts store for only a few dollars. I prefer the brass variety. Original GM are steel. Your choice, though. The parts store will usually have both in any size that you require.

5) Usually, the big problem with freeze plug replacement is getting at the leaking plug with enough working room to remove and re-install a plug. If the one that you need to replace is one of the easy ones, consider yourself fortunate.

[Chris H.]

Re: freeze plug repair questions.

Thanks Joe. Yes, fortunatly the freeze plug in question is the one behind the starter. With the starter removed there's enough room to stick a basketball in there.

[Bill Bradley]

Re: freeze plug repair questions.

Another method that works well on freeze plugs is to drill a hole, install a large sheet metal screw and pull it out with a claw hammer or a cats paw when space is tight. By the way they are really Welch plugs and plug up the holes that are in the block casting to remove the casting sand. They just happen to come out first (hopefully) if the coolant freezes.