Freeze plugs

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Freeze plugs

Post by Modeltmike » Thu Dec 26, 2019 5:26 am

I replaced my freeze plugs last year. I had the choice of brass or steel. I used brass for no specific reason. The block castings seems to be smooth and clean. An engine builder I know told me to coat the plugs with some brown sealer that he recommended. They still seep just a little. Wanted to get some opinions. Brass vs steel? Should I give them another “tap” to make sure they are seated? The dome is pointed out? Always like to learn from others. Thanks Mike

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Re: Freeze plugs

Post by Chad_Marcheese » Thu Dec 26, 2019 6:11 am

The material makes no difference. I prefer brass plugs because of the corrosion resistance over steel. The brown stuff he recommended was probably what used to be called "Indian Head", but I think is now just called Gasket Shellac. I too have used it on countless freeze plugs over the years and have had no issues. I coat the block surface and the edges of the plug where they meet the block.

You can attempt to try and give the offending plug(s) a little more of a tap, but it may make them leak more. And if you did use sealer, it may upset the seal that has already taken place.

Permatex part# 20539
Napa Part# 765-1229 ... -compound/

Hope that helps some.

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Re: Freeze plugs

Post by Wayne Sheldon » Thu Dec 26, 2019 6:27 am

Most prefer brass or nickel. Seriously, a genuine US five cent coin. Purists will use a buffalo nickel. Others are content with a Jefferson nickel. They must be dished a bit first, but actually can work okay. And not only that, the silly things are cheaper than buying the genuine plug manufactured for the task.
If you didn't ding the center of your new plug well enough before, a careful blow or two with the ball-peen hammer to dimple the center in a bit more may (or may not?) fix it. If hammered in too much, the plugs can "self-crush" and may never tighten okay. Brass plugs are more prone to self crushing than the steel ones are. That being the primary reason that some people do prefer the steel plugs. However, steel plugs do have a much greater tendency to eventually fail due to internal rusting.
There are a variety of sealers that different people like to use. Some sticky brown stuff, Permatex in several qualities. I like Permatex number two (the non-hardening variety). I have also used J B Weld or just epoxy in a small amount applied before installing the plug.

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Re: Freeze plugs

Post by John kuehn » Thu Dec 26, 2019 8:51 am

I used a nickel out of pocket change to replace a freeze plug that had been used when I had the blocked cleaned up. The brass one wasnt dished out enough so I used the nickel. It worked fine and an exact fit with a hammer tap. And it wasn’t a buffalo nickel.

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Re: Freeze plugs

Post by George House » Thu Dec 26, 2019 9:06 am

I, too, have used an Indian head nickel on numerous occasions after dishing it out with a ball been hammer on a 11/16” socket. Just hit the peen onto the nickel with another hammer...BUT...I’ve recently had a problem blowing out 1 5/16” freeze PLUGS on my ‘50 Ford tudor. I finally mixed up some JB Weld and applied to the block hole and beat the concave sufficiently for a successful fix....
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Courage is a Decision”...Sir Winston Churchill

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Re: Freeze plugs

Post by Steve Jelf » Thu Dec 26, 2019 10:21 am

I found that old time Permatex hardened and eventually failed. Ultra Black has been OK so far.
The inevitable often happens.
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Re: Freeze plugs

Post by Aarongriffey » Thu Dec 26, 2019 1:04 pm

Permatex no.2 works just fine but so does hard setting no.1
RTV or Indian Headdoes the job too. So does Gasgasinch And monkey sweet.
The secret it to flatten the core plug enough.
I have seen many core plugs installed dry.

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Re: Freeze plugs

Post by Norman Kling » Thu Dec 26, 2019 1:34 pm

When you put the plug in, use a large flat punch in the center. That will flatten the plug rather than dish it in in the center. A large bolt or even a 1/2 inch socket extension will do for a punch As said above, use sealer around the edge. If it still seeps a little after you put it in, clean the area well and spread a bit of sealer around the edges. usually that is enough to fix it and any leak will not be big enough to cause you to loose your coolant while driving unless the plug comes out.

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Re: Freeze plugs

Post by Tim Williams » Thu Dec 26, 2019 1:41 pm

I used Steve Jelf's tips page and it answered all my questions about freeze plug replacement.

Tim Williams

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Re: Freeze plugs

Post by Modeltmike » Fri Dec 27, 2019 3:20 am

THANKS for all the info! Experience is the best teacher. I should be able to make the seep go away.

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Re: Freeze plugs

Post by Luke » Fri Dec 27, 2019 5:31 am

Minor thread drift/useless information...

... this is proof that things are bigger and better in the U.S. as it clearly gets a lot colder than here, where we just call them frost plugs :)

Otherwise we have a product ('Bar's leaks') that combines a little soluble oil and some coagulent that if put in the coolant seals up minor leaks such as you describe. If you tried whatever is your equivalent product it may sort the seeping issue and also assist your water pump, if you have one that is.

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Re: Freeze plugs

Post by Dan Hatch » Fri Dec 27, 2019 7:05 am

Correct term world wide is “Welch Plug” AKA Core Plug.

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Re: Freeze plugs

Post by JohnH » Fri Dec 27, 2019 8:07 am

First thing I learned about the repro welch plugs is not to use the steel ones. They rusted through in a couple of years. Having being caught out, I then used an Australian 2 cent coin, suitably dished. Then JB weld after punching it in. No more problems.

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