Leaking soft plug

[Doug&Deb]

I’m going to be replacing a leaking soft plug on my Coronet and I’m wondering what everyone recommends for a sealant. This is a fairly recent rebuild and one of the only things I didn’t do myself. I’m glad only one is leaking so far. Hope it stays that way.

[junkers72]

I replaced a few and didn’t use any sealer. Just made sure the block was clean. Used a wire brush for a drill and sprayed with brake parts cleaner. They weren’t all too easy to get a straight shot at with engine in the car but worked out for me. 

[Adam H P15 D30]

I clean and JB weld my core plugs in, mostly on Hemi engines that have a history of blowing them out on hard use.  They use the same plugs as our flatheads and still come out when replacing.

[D35 Torpedo]

The right stuff by permatex

[Sniper]

I never used sealant on them.

 

https://youtu.be/rjmVdUmKuBghttps://youtu.be/rjmVdUmKuBg

[andyd]

If the block area is clean and clear of any crud on the plug hole then you shouldn't need any sealer, the 1 & 5/8th plugs are a good fit and lock into the hole edges .........a light application of any non hardening gasket goo won't harm it........andyd 

[desoto1939]

6 hours ago, Sniper said:

I never used sealant on them.

 

https://youtu.be/rjmVdUmKuBghttps://youtu.be/rjmVdUmKuBg

This was great video on how to install the plugs and remove the plugs.  Thanks for posting.

 

Rich Hartung

[Dodgeb4ya]

As Adam H said....JB weld

I do the same on the Hemi's because of high volume and pressure on HP engines.

Still a good thing to use on six or eight cylinder engines.

Just install them correctly using JB Weld.

They will never leak or pop out.

 

[D35 Torpedo]

Has anyone ever tested or verified that ice will push the plug out when you jb weld them? Seems excessive. I use the smallest amount of the right stuff just for insurance, incase there is a flaw. 

[Sniper]

4 hours ago, D35 Torpedo said:

Has anyone ever tested or verified that ice will push the plug out

 

That is not their job and if you ever have ice in your block to the point that it will push out a core plug you probably have a cracked block.

[Adam H P15 D30]

8 hours ago, D35 Torpedo said:

Has anyone ever tested or verified that ice will push the plug out when you jb weld them? Seems excessive. I use the smallest amount of the right stuff just for insurance, incase there is a flaw. 

Ice will crack your block long before any core plug will pop out.  They are there to remove casting sand, any other function is a myth.

[D35 Torpedo]

I've always called them frost plugs. Other names are core plugs, welch plugs, expansion plugs and freeze plugs. Depending on what name you search, you get a different purpose. I've always considered them to be a way of saving a block from freezing. I've seen it many times...but you guys are also correct about the sand thing. Id say they do both. 

[Matt Wilson]

Do you guys use sealant (JB Weld, Right Stuff or other) when installing the plug that's directly behind the camshaft?  Since that one is exposed to oil (or rather, the oiling system of exposed to it), is there any significant risk of getting pieces of sealant in the oil?

 

I guess one might think there's no difference between using sealant on this plug and using it on a gasket, but I can see how there would be a tendency to want to use more sealant on the plug than on a gasket; hence my question.

Edited December 16, 2023 by Matt Wilson

[Doug&Deb]

I’m having a rough time finding the correct 4lb radiator cap for my car. Where are you guys finding any?

[Sniper]

3 hours ago, Doug&Deb said:

I’m having a rough time finding the correct 4lb radiator cap for my car. Where are you guys finding any?

 

https://www.summitracing.com/parts/snn-t4

 

https://www.napaonline.com/en/p/BK_7031412

 

https://www.rockauto.com/en/moreinfo.php?pk=4592436&cc=0&pt=2068&jsn=273

 

 

Edited December 17, 2023 by Sniper

[Dodgeb4ya]

9 hours ago, Matt Wilson said:

Do you guys use sealant (JB Weld, Right Stuff or other) when installing the plug that's directly behind the camshaft?  Since that one is exposed to oil (or rather, the oiling system of exposed to it), is there any significant risk of getting pieces of sealant in the oil?

 

I guess one might think there's no difference between using sealant on this plug and using it on a gasket, but I can see how there would be a tendency to want to use more sealant on the plug than on a gasket; hence my question.

On that plug....oil hits it, I always use Permatex  #1 or 2.

The right Stuff  works fine too.

The coolant plugs are the critical ones to seal against leakage and possibly coming out from improper installation.

[Matt Wilson]

7 hours ago, Dodgeb4ya said:

On that plug....oil hits it, I always use Permatex  #1 or 2.

The right Stuff  works fine too.

The coolant plugs are the critical ones to seal against leakage and possibly coming out from improper installation.

Thanks very much!  Just curious.....why would the coolant ones be more critical, and why more likely to come out due to improper installation?  I've got some thoughts on why that might be the case, but would like to hear your thoughts.

[Dodgeb4ya]

The coolant plugs can leak because of corrosion pitting in the plug counter bore recess.

Not all blocks today have like new pit free counter bores.

Also there seem to be so many plugs that are not installed properly and prematurely pop out.

They really need to be driven in almost but not quite flat with a large heavy drift.

3/4 the size of the plug using a heavy 2-3 lb. Hammer.

Two to three straight on moderate firm hits will fully set the 1-5/8" plugs.

Installing plugs in the car or truck is difficult for sure but can be done...best to remove the inner fender panel on that situation for guaranteed results.

Spend the time...install them right IMO.

[Sniper]

My philosophy on replacing a leaky core plug?  Pull the engine, replace them all.  If one is going odds are others are close.  May as well clean up the engine, pull the pan and desludge it, seal up the rear main if need be, repaint the engine. 

 

Then you are done with it and no more farting about replacing them as they start to leak.  Be a good winter project for those of you that live in the snow belt.  This is something I would do with my son as a project since my grandson is only three months old. 

[Sniper]

I guess I should add that cleaning all the crud out of the water jackets while you have the engine out and the plugs removed it also on the to do list.  Maybe even a water distribution tube, lol.  May as well run a torque wrench around the head bolts.  Replace the block drain plugs with a petcock that has a nipple on it.  The snow ball rolls.

[Doug&Deb]

Sniper I agree but in my case the engine was just rebuilt last winter and installed in the spring. I’m definitely replacing the leaking plug and I’d love to find a drain petcock with a nipple on it. I can’t find those anywhere. If anyone has a source for that please share it with us.

[Dodgeb4ya]

1/4" drain petcock block or radiator...

[Sniper]

6 hours ago, Dodgeb4ya said:

1/4" drain petcock block or radiator...

 

I tried those, they leak and the wings slip.  So I got two of these, one for the block, the other for the radiator

 

https://www.amazon.com/gp/product/B07Q2NGJV7/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

[Dodgeb4ya]

I agree the moderm chinese ones are total junk.

I have soldered the wing up too.

Never had one leak.

I have saved up good oem  used ones.

[9 foot box]

   An Edelmann 308400 drain valve has a hose nipple. It is 90* and looks like the original 907782 that are in my cars.