Sealing an expansion plug???

Harold Hubbard · Apr 30, 2020

I spent the afternoon unbolting and lifting the gas tank and steering box from my IH 350 U. The expansion plug in the bottom of the box has been leaking for a while, and this was a good rainy day project. BUT, it was all the fun I need for a while and I don't want to do it again very soon. So what is the best sealant to use around the new plug? I have always used #1 Permatex, but was wondering if anyone had other suggestions.

Steve@Advance · Apr 30, 2020

Permatex is as good as any.

If there are any other plugs that are now accessible, this would be the time to replace them too.

I like the copper expandable type, with the brass acorn nut in the middle. They are easier to put in if you can't get a good hammer swing at them, and are permanent, will not corrode through like steel.

If there is a layer of black sludge behind the plug, that stuff is corrosive and will eat through a steel plug in a short time.

fastfarmall · Apr 30, 2020

I put new soft plugs, in my 806 engine block, they were Dorman brand, i just cleaned the inside bore with sand paper, just tapped on the center with a brass punch, they have never leaked, that's what holds the Amti-Freze in the block! But not saying that's right was to do it!!

Harold Hubbard · Apr 30, 2020

This plug seals the bore of the steering shaft, and unfortunately there is not enough room behind it for the bolt in type. The nasty stuff was a mixture of old oil, loose rust and water. The plug showed no sign of corrosion, but was loose in the pocket, and showed signs of abuse where someone had tried to tighten it by beating it.

Hopefully I can get a good straight shot at it with enough force to seat it without pounding it forever.

Steve@Advance · Apr 30, 2020

OK, I saw expansion plug and thought water jacket of the engine block.

In your application corrosion is not going to be an issue.

shinnery · May 1, 2020

I think I would try to find a socket that just fits in the plug to drive it in and not apply pressure in the center of the plug, unless it is the convex disk type plug, then you want to flatten the plug out in the hole.

TKiste · May 1, 2020

I found spraying the clean hole with paint and then seating the plug worked great for me.

Hobo,NC · May 1, 2020

Permatex Aviation Form-A-Gasket No. 3 Sealant has been my go to I have tried other sealers I always go back to #3... I have installed 100's of em always use a drive in plug are what was OEM not one of those Steve recommended and WHY its cuzz I have replaced a many of those leaking hack job plugs... They are not a permanent solution and trouble in the making... I did say HACK and that's what they are...

What kind of plug is it the flat concave plugs are set with a hammer or punch...

David G · May 1, 2020

I usually use Indian Head Sealer.

Sealing an expansion plug???

Harold Hubbard

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Steve@Advance

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fastfarmall

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Harold Hubbard

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Steve@Advance

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shinnery

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TKiste

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Hobo,NC

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David G

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