Leaking core plug in the head 351C

I pulled off the valve covers today and noticed one of my six sided core plugs on a 351C (H Code) had a very small link of antifreeze near cylinder number 5. What is the best way to stop this leak? with some type of head stop leak? or replace the core plug? Where can you get these core plugs and how do you remove them?

I pulled off the valve covers today and noticed one of my six sided core plugs on a 351C (H Code) had a very small link of antifreeze near cylinder number 5. What is the best way to stop this leak? with some type of head stop leak? or replace the core plug? Where can you get these core plugs and how do you remove them?

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Can you post a picture so we can be sure what you are looking at?

I had this happen many years ago you can get them that have a bolt in the center so you can put them in while in the car. But if one leaks they are all in bad shape. You need to pull the engine to replace them all it is much quicker than trying to do it in the car. Some people refer to them as freeze plugs but they were put into the casting to give a place that the sand could be removed after the casting process so core plug is a correct statement. The factory machines the holes and there are stamped steel plugs you can get at most any parts store to replace them. I had to change mine I think at 7 years old.

You guys that work on these all the time is there not two behind flywheel or am I dreaming been a long time since I replaced them.

David

I pulled off the valve covers today and noticed one of my six sided core plugs on a 351C (H Code) had a very small link of antifreeze near cylinder number 5. What is the best way to stop this leak? with some type of head stop leak? or replace the core plug? Where can you get these core plugs and how do you remove them?

Click to expand...

Nix the "Stop Leak" idea. That will lead to other issues later! Drain the fluid and replace the leaking culprit. Do the job right the first time and it will pay dividends later. Just my two cents.

Short of having an Allen wrench that big, I'd see if one of those threaded rod couplings would fit the female socket of the core plug. Then use it and the appropriate socket and breaker to unscrew the plug.

Yikes!. Those plugs are monsters. We used to use oxy/acetylene torches and big 3/4" drive impact guns to get them out.

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yeah, it aint gonna move easy so heres another option.

Clean the area around the screw with brake cleaner. Mix regular old trans fluid 50/50 with acetone or use kroil oil and dribble a little around the screw every 6 hours maybe for 3 days then try to remove it.

After it fails to move, buy a few cans of “dust off” compressed air. All the hardware stores sell it.

turn the can upside down and spray it on the offending screw and surrounding area for around 15 seconds then wait one minute.

Spray offending area for around 30 seconds.

Remove screw with ease?

those are hard to find . . below is one place you can buy them.

https://www1.mscdirect.com/PDF/FASTENERS/SocketSetScrews.pdf

heres the various types that will work

socket set screw

socket cup screw

socket cup point grub screw

cup point socket set screw . . most common

flat point socket set screw . . cheapest