What Size Freeze Plug?

[Hikin Mike]

Car is a 68 Coronet 318. Was using a hose trying to clean some of the junk on the motor, and I now see a little fountain on one of the freeze plugs. It's on the front near the fuel pump.

I'm not ready to change them all, just the bad one. Do you know what size this one is?

 

[69L48Z27]

1 5/8” In the block and some are 1 1/4” for the smaller ones like in the head. I’m trying to remember if all the block ones are the 1 5/8” on a small block.

 

[69Bee]

1 5/8" x 9 and 1 1/4" front pass side of block, and yes, 1 1/4" x 4 on the heads.

 

[Hikin Mike]

Thanks for that. Next project once the car can stop.

 

[493 Mike]

1 5/8" x 9 and 1 1/4" front pass side of block, and yes, 1 1/4" x 4 on the heads.

Don't forget the 2 on the back of the block.
Mike

 

[69Bee]

Don't forget the 2 on the back of the block.
Mike

2 rear, 6 side, 1 front = 9

 

[493 Mike]

2 rear, 6 side, 1 front = 9

I added 2 in the back because many don't know about them.
Mike

 

[YY1]

These are what I use.

Note the thickness and depth difference between the left (and box) and the right.

The one on the left will install MUCH easier and be far less prone to popping out.

Just noticed made in china....grrrrr

 

[69Bee]

These are what I use.

Note the thickness and depth difference between the left (and box) and the right.

The one on the left will install MUCH easier and be far less prone to popping out.

View attachment 978614
Just noticed made in china....grrrrr

A properly installed core plug will not "pop" out, even the shallow plugs. The OEM's have used shallow plugs for decades with no problems. The key is to seal them CORRECTLY, and install them straight. You also have a much greater chance of a leaking plug or one falling out with those brass plugs. They are malable, and if not installed properly, they deform, and will not fit correctly. Of all of the plugs I have removed, the only loose or popped out plugs were brass. I refuse to install brass, only steel, and use the previously mentioned (another thread) "Core Plug Sealant" by Loc-Tite, and have NO leakers. It also lubricates the plug for easier installation, and once dry (about 5 minutes), the plug is locked in place.

 

[YY1]

That's funny because I use ONLY brass and NEVER use sealant.

Never had one leak that didn't stop after a heat cycle and I can count those on one hand.

I've never seen a brass plug rust out either.

All the OEM Chrysler plugs I've taken out look exactly like the thin, deep plugs I posted but were steel.

The shallow, thick plugs tend to be springy, and are difficult to get in straight.

The deeper plugs usually will straighten themselves if the initial hit is not perfect.

 

[69Bee]

That's funny because I use ONLY brass and NEVER use sealant.

Never had one leak that didn't stop after a heat cycle and I can count those on one hand.

I've never seen a brass plug rust out either.

All the OEM Chrysler plugs I've taken out look exactly like the thin, deep plugs I posted but were steel.

The shallow, thick plugs tend to be springy, and are difficult to get in straight.

The deeper plugs usually will straighten themselves if the initial hit is not perfect.

They do straighten out usually. I use and modify aluminum drivers so that it goes in straight, and also can set the depth. I am not saying they won't seal, I just don't like them. I had leakers every now and then with the steel, and using Permatex #3 non-hardening sealer, but changed over to the Loc-Tite product and now have none. I just prefer steel over brass is all. With a properly maintained cooling system, the steel should last a long time, they just don't look as purty at the brass ones.

 

[Hikin Mike]

FWIW, the one that was bad was the small one, 1-1/4".