Freeze plugs

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70Duster340

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Can anyone advise why a freeze plug would fall out without any use? The 340 is sitting in a wooden engine cradle, where it's been for a while now. I noticed recently that the right side front freeze plug had fallen out. There's no water in the engine, so I am at a loss about why it happened.

Since I will need to replace it, should I remove them all and reseal and replace them?

Thanks
 
Measure the frost plug opening with a caliper and compare the outside diameter
of a new frost plug.

Want to make sure the frost plug opening has not been opened up where someone was trying to remove surface rust and pits.

If there are steel frost plugs in it, I would knock them out and put in a set of brass ones as they are a little softer and will grab better.

Want to make sure they fit snug when tapping them in with a socket that just fits inside them.

Brush on a coat of High Tack Sealer on the new frost plug and the block opening before tapping them in.
 
George Jets said:
Measure the frost plug opening with a caliper and compare the outside diameter
of a new frost plug.

Want to make sure the frost plug opening has not been opened up where someone was trying to remove surface rust and pits.

If there are steel frost plugs in it, I would knock them out and put in a set of brass ones as they are a little softer and will grab better.

Want to make sure they fit snug when tapping them in with a socket that just fits inside them.

Brush on a coat of High Tack Sealer on the new frost plug and the block opening before tapping them in.
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I appreciate the input. These were new brass freeze plugs. They didn't blow out when the engine was run on the stand after the rebuild for the cam break in. Do you think it would be a good idea to replace them all?
 
70Duster340 said:
I appreciate the input. These were new brass freeze plugs. They didn't blow out when the engine was run on the stand after the rebuild for the cam break in. Do you think it would be a good idea to replace them all?
Click to expand...
Tap on the rest to see if they are lose. Chances are it was put in cockeyed then taken back out and re hammered back in... so it lost its size and fell out...perhaps.
 
When I overhauled the 440-6 engine way back in the 70's I was told by the shop that it had OVERSIZED CORE PLUGS

You may know, but they are "not" 'freeze plugs'. They have no function other than allowing the factory to cast the block. "Core plugs"
 
70Duster340 said:
I appreciate the input. These were new brass freeze plugs. They didn't blow out when the engine was run on the stand after the rebuild for the cam break in. Do you think it would be a good idea to replace them all?
Click to expand...

You will want to look at the one that came out and compare to new one to see if you can figure why it dropped out, unless you had water in the lower block and it froze pushing it out.

Like I say those frost plug bores can rust and pit real bad, so you want to make sure they are staight and clean. Then put in another new one and make sure it goes in snug. (They may have cocked the first one bending it out of shape before it went in.)

Then you can go around with your install socket and tap firmly on the others and make sure they don't move. But not hitting them so hard that you drive them in more.
 
67Dart273 said:
When I overhauled the 440-6 engine way back in the 70's I was told by the shop that it had OVERSIZED CORE PLUGS

You may know, but they are "not" 'freeze plugs'. They have no function other than allowing the factory to cast the block. "Core plugs"
Click to expand...
Yeah, but if you look them up on auto parts websites, they're either called freeze plugs or expansion plugs.
 
George Jets said:
You will want to look at the one that came out and compare to new one to see if you can figure why it dropped out, unless you had water in the lower block and it froze pushing it out.

Like I say those frost plug bores can rust and pit real bad, so you want to make sure they are staight and clean. Then put in another new one and make sure it goes in snug. (They may have cocked the first one bending it out of shape before it went in.)

Then you can go around with your install socket and tap firmly on the others and make sure they don't move. But not hitting them so hard that you drive them in more.
Click to expand...
The block was drained completely after the engine had been broken in. I guess what I don't get is, if it was slightly sideways in the bore, why it didn't come out when it was running?

I have a good micrometer somewhere in my garage. I'll find it and take a measurement.

What holds the plug in, anyway?
 
70Duster340 said:
The block was drained completely after the engine had been broken in. I guess what I don't get is, if it was slightly sideways in the bore, why it didn't come out when it was running?

I have a good micrometer somewhere in my garage. I'll find it and take a measurement.

What holds the plug in, anyway?
Click to expand...

The plug is slightly oversized, so when you tap it in it is a pressure fit that holds it in place along with the sealer after it has dried down.
 
The weird plug at the end of the camshaft galley is a Welch plug, you place it in there convex side out and whack the center with a ball pein hammer. It expands and seals after that. If your core holes are jacked, you can always use a rubber expansion plug.
 
pishta said:
The weird plug at the end of the camshaft galley is a Welch plug, you place it in there convex side out and whack the center with a ball pein hammer. It expands and seals after that. If your core holes are jacked, you can always use a rubber expansion plug.
Click to expand...
How long will those hold up?
 
There are at least two types of brass freeze plugs.

The thick, shallow type, and the thinner, deep type.

The deep type is way better.

The shallow type is very easy to seat crooked and can spring back out.

I generally do not use any sealer on them, they are not designed for it.

If you are concerned, I'd use something like "Coppercoat".
 
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I had this happen in the race trailer. We drained the water for the winter. We thought it was empty . The one plug fell out. We decided to reinstall them all. Came to find out there was still water in the other side, Yes we had opened the side drain plugs and closed them before we left it down and parked it. After that occurred we just left them open for the winter. There was no damage to the block.
 
Oldmanmopar said:
I had this happen in the race trailer. We drained the water for the winter. We thought it was empty . The one plug fell out. We decided to reinstall them all. Came to find out there was still water in the other side, Yes we had opened the side drain plugs and closed them before we left it down and parked it. After that occurred we just left them open for the winter. There was no damage to the block.
Click to expand...
I see your point. I suppose there could still be some water in the block.
 
I have had casting sand block one of the pan rail block drain. Pull the plug and nothing comes out but there is still water on that side of the block. I believe that might be what happened and the water froze and popped it out. Pull the block drain plug and run water through the block. See if water drains out of both sides.
 
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