72 LT-1 Freeze Plugs

[John L.]

On my newly aquired 72 LT-1 engine the freeze plugs had been changed out to Dorman Products brand plugs around 1975 when the engine was pulled. What would be the correct type/brand to replace with? Also it's been at least 30 years since I replaced a freeze plug, what is the correct method of removal and replacement? Thanks.

[Terry M.]

Re: 72 LT-1 Freeze Plugs

The original steel core plugs had no brand or marks on them. Your challenge will be to find some without marks.

I have never replaced one. I guess I just have missed out on that experience. I have lead a rather sheltered life, mechanically. Small block Chevrolet engines, like your LT1, are the same back to dirt. If you did it years ago, it hasn't changed.

[Joe L.]

Re: 72 LT-1 Freeze Plugs

On my newly aquired 72 LT-1 engine the freeze plugs had been changed out to Dorman Products brand plugs around 1975 when the engine was pulled. What would be the correct type/brand to replace with? Also it's been at least 30 years since I replaced a freeze plug, what is the correct method of removal and replacement? Thanks.

John-----


Punch the freeze plug INWARD at the bottom. That will cause the upper edge to pivot out. Grab the upper part with channel lock pliers and "wiggle" it out.

Use BRASS freeze plugs. If there are any markings, you can "obliterate" them with a little JB Weld, dressed out after curing. After painting the engine block, no one will know the difference except a judge with a magnet. If that bothers you, use steel plugs and "obliterate" any markings in the same manner.

[John L.]

Re: 72 LT-1 Freeze Plugs

Thanks Joe & Terry. I did do it 30 years ago...problem is, it was 30 years ago. I knew the original ones didn't have markings on them and these do say Dorman Products on them. I would like to find some plain looking ones if possible. As I remember I should use some sort of sealer on the rims of the new freeze plugs before reinserting them. I think I used a large socket to tap on to drive them in with...does that sound correct?
Appreciate your responses.

[Jack H.]

Re: 72 LT-1 Freeze Plugs

Last I checked, you could still get brass freeze plugs from GM that had no visible markings, but they were PROUD of them in terms of price!!!

[Terry M.]

Re: 72 LT-1 Freeze Plugs

Sounds right to me. I think Joe's suggestion of brass is the best solution. No corrosion in our lifetime with brass -- even if you put the engine in your boat. If the engine is out of the car the socket is the best method. There is a tool for setting core plugs in the car, but it only elaborates on a socket and allows for the sometimes-limited access of the chassis.

I'm not sure what sealant to use, but someone will offer a suggestion or two or three.

[Terry M.]

Re: 72 LT-1 Freeze Plugs

Last I checked, you could still get brass freeze plugs from GM that had no visible markings, but they were PROUD of them in terms of price!!!

Sometime in the '90s -- before the iron block went away for any Chevrolet application -- Flint began to install brass core plugs. I recall receiving some documents from them that detailed the change. To the guys at Flint that was a very big deal. Those papers should be at the AACA Library in Hershey, if someone is interested enough to seek them out.

[Dick W.]

Re: 72 LT-1 Freeze Plugs

Use #2 Permatex for the sealer John. If you are replacing all of them, it would almost be quicker to lift the engine. The front two plugs are a *(&(!

[Joe L.]

Re: 72 LT-1 Freeze Plugs

Thanks Joe & Terry. I did do it 30 years ago...problem is, it was 30 years ago. I knew the original ones didn't have markings on them and these do say Dorman Products on them. I would like to find some plain looking ones if possible. As I remember I should use some sort of sealer on the rims of the new freeze plugs before reinserting them. I think I used a large socket to tap on to drive them in with...does that sound correct?
Appreciate your responses.

John-----


An appropriate-sized socket makes an excellent driver. Also, bearing race driver tools will work well (and, keep you from beating on your sockets).

Any good sealer will work on these. I've always used Permatex non-hardening sealer. However, I think that silicone RTV will likely work as well.

[John L.]

Re: 72 LT-1 Freeze Plugs

Thanks Dick,
The engine is out, on a stand, awaiting cleaning and rebuilding.
I assume that all are the same size....right?

[John L.]

Re: 72 LT-1 Freeze Plugs

Joe, Ilike your idea of using a bearing race driver set up. I was looking at a set of those yesterday.........sounds like a good reason to buy one. I guess I could use them also on front wheels.

[Joe L.]

Re: 72 LT-1 Freeze Plugs

Joe, Ilike your idea of using a bearing race driver set up. I was looking at a set of those yesterday.........sounds like a good reason to buy one. I guess I could use them also on front wheels.

John-----


Yes, they have "alternate" uses. They are not too expensive, either.

[Dennis C.]

Re: 72 LT-1 Freeze Plugs

John,

If you find you are having trouble driving in the new freeze plug, leave them in the freezer for a few hours. When you are ready, remove one, put your sealer on and drive it right in. It helps to make the job a little easier.

Regards,

Dennis

[John M.]

Re: 72 LT-1 Freeze Plugs

John,

If you find you are having trouble driving in the new freeze plug, leave them in the freezer for a few hours. When you are ready, remove one, put your sealer on and drive it right in. It helps to make the job a little easier.

Regards,

Dennis

Is that why they call them freeze plugs?

Just kidding, I jut came in from the garage replacing the one under the rh mount, in car. High patience quotient required, but got it.

[Terry M.]

Re: 72 LT-1 Freeze Plugs

John, No need for the freezer where you are -- just leave them outside.