Blown Frost Plug

[greeno]

Got a mile from home today and noticed the truck was over heating. Once it was cool enough I added some water to the radiator…and it came pouring out the frost plug behind the starter! Grrrr….no parade for me Sunday!

This is a fresh rebuild. What could have happened and what should I note when reassembling? The head was hot, 300f on the IR gun.

[Cal_Gary]

Sorry to hear that, Greeno.
Once you get to it, remove the leaker, apply sealer to the new cap, then seat it with the high side facing you, then stake it with a solid dimple in the middle with your ball peen hammer.

For those who aren't aware, those are actually the casting plugs when the block was poured, to allow the sand to be dumped once out of the forge. They may not do anything in a "freeze" situation.
Gary

[RCrombie]

Of course it would be one that’s tricky to reach! You might be in luck and be able to access it from inside the cab if you remove the panel on the firewall. I’m going to guess that either the plug was defective or wasn’t dimpled properly to hold it in place.
Often the problems are with the core plugs weeping, not popping right out.
At least they’re inexpensive and not difficult to replace, provided you can get at it and have enough room to set it in place.
Let us know how it goes! Maybe you’ll make the parade after all.

[greeno]

What kind of sealer should I use?

I ordered the whole set this morning; one of the upper plugs is weeping I should probably change that too.

[Murf]

I swear by (not at) Permatex Type 3 Aviation.
I have NEVER had a failure. It does get everywhere and is hard to get off.Use lacquer thinner.

[greeno]

I can get at it. Fingers crossed I can dimple it tomorrow!

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Look what I found behind the plug!!!

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[Cal_Gary]

WOW!
I fished a wire out of my head's heater plug upon removal once.
Glad you have access to it!
Gary

[greeno]

In my panic I left the ignition on. Coil burned for sure (open circuit between posts). NOS coil from John and still no spark.

Can u burn up a Pertronix? How do you test them?

[John Mc]

I believe you can burn up a Pertronix.

The installation manual for the Pertronix MV-161A Ignitor I have installed in my M37 has a Q & A section. One of the questions reads as follows:

Q: What happens if I leave the ignition switch on when the engine is not running?
A: This can cause your coil to overheat, which may cause permanent damage to your coil and the Ignitor.

[NAM VET]

just had a bit of a stumble under load, fuel is fine, so checked three of my spare coils, old OEM and two chrome ones, none had any Ohm resistance across the secondary coil, but ran 7-12 ohm across the two terminals. So just ordered two spares from these people, mentioned in another coil post the other day, hav two coming, Peter there told me these are much better. Hal

here:

https://www.debellajeepparts.com/orderinfo.htm

[greeno]

Just put new points back in and still no spark. Not looking good at all for the parade

[John Mc]

All three spare coils showing the same problem is a bit odd. Are they all shorted (0 ohms) or open (infinite)?

[NAM VET]

all I know is that when I touch my pos digital lead to the center electrode, and the neg probe to the neg pole, I get no reading at all. Tried lots of times. Tried it the other way too, nothing. Two were old OEM's I happened to have, one labeled as working when removed, the other a never used chrome one. I have a master cut off switch, and always turn it off too when Turing my engine off with the main switch. I have a Pertronix with no issues since installed. Hal

[greeno]

My frost plug replacement came out on my first test drive today. Argh!

[PoW]

You have to really set that plug with a mandrel of some kind (I use a socket & extension) if it is a cup type plug.

If it is a watch glass type, you have to push in in, then upset the dome by hammering the thing with a drift about half the diameter.

PoW