Core plugs.... rtv or dry?

[bigcountry78]

Alright fellas, need some input. About a month ago I had to put a starter on my truck. While I was doing that, I replaced the freeze/core plug behind it that was leaking. I put some rtv on it and put it in but it went in too easy. I let it cure 24 hours before I added coolant and all was good until today, when the plug blew out along with my coolant. I was about 3 miles from home so I made it to my wife’s grandfather’s house. Long story short I test fit the new plug and now it’s lodged in the block without rtv. I hammered it on in and drive home, it seemed to hold. So am I good as is? Or do I wait until it blows out and re seal with rtv? What is the group consensus?

 

[legopnuematic]

I did the ones on my 79 with no sealer. I want to say I've read that putting certain sealers on them can make they "slippery,"but don't hold me to that statement

Sent from my Moto Z (2) using Tapatalk

 

[Dutch Rutter]

I've always used brass plugs and permatex #2, works great. I would not use RTV, you need something to harden for core plugs. I've also been told by a mechanic shop to use some loctite and pound them in, I haven't personally done this but I'm sure it'll work too.

 

[Turbo4whl]

Some thoughts for you younger readers. The small block engine was designed in 1950's, well before RTV was used in the automotive field. Permetex #1, #2 and #3 (aviation Permetex) were the sealants of choice for almost everyone.

#2 Permetex for core plugs, thermostat and water pump gaskets.

#3 for valve cover, axle cover and transmission gaskets and even repairing carburetor gaskets.

#1 only for items you do not expect to ever take apart again. One of #1 Permetex originally designed uses was to replace stamped steel head gaskets.

I would not recommend RTV or Loctite to seal a core plug.

 

[Snoots]

If you used RTV, better. If not, if it don't leak, don't fix it. Hopefully they were BRASS!

 

[bigcountry78]

Thanks everyone, it sounds like I may be ok as long as it doesn’t leak. And I used permatex on the first one, I’ll have to check and see which number it was. I was calling it RTV but that may be incorrect.

EDIT: ok it was red permatex brand RTV, so maybe that was the problem. And it was a steel plug. The originals lasted 40 years lol.

 

[Bennyt]

I've used Gasgacinch for years and never had a failure. One bottle lasts forever. You can buy slightly oversize plugs for rust damaged or blocks that have bad castings. When I worked at the machine shop as a kid, probably 1 in 200 needed an oversize plug.

Brass plugs last longer but the factory used steel and there's plenty of 35 year old blocks still running around on the original plugs.

You could always put a rubber temporary plug in your glovebox just in case.

 

[eskimomann209]

I've used Gasgacinch for years and never had a failure. One bottle lasts forever. You can buy slightly oversize plugs for rust damaged or blocks that have bad castings. When I worked at the machine shop as a kid, probably 1 in 200 needed an oversize plug.

Brass plugs last longer but the factory used steel and there's plenty of 35 year old blocks still running around on the original plugs.

You could always put a rubber temporary plug in your glovebox just in case.

I have seen them rubber plugs last for years. I put one in a buddy’s truck 10 years ago and he never came back to have me change it for the right one. It weeps tho. I can see the water stain under it. I do brass with no sealant. But I wouldn’t turn it away if I had some no2 form a gasket. I just smear it around the plug thin like and tap it in.
My issue is I usually need a spare. I have big hands and sometimes send one in a little **** eyed due to impatience lol.