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So I'm in the middle of my fuel injection swap and I did something really dumb.

I forgot to fill the engine with coolant and ran it for a couple of minutes. ~x(

The radiator cap popped off and I got a nice burst of steam out of the radiator. I'm assuming that was from the remnants of what water was left in the block.

I let the engine cool off completely before I filled it with water. I didn't want to crack anything by dousing it.

I know that my heater core is leaking so I have another one on the way. What else do I need to look for? I'm assuming I should check the engine oil to see if it has any water in it. I filled the coolant and ran it a bit and it has no oil in it so that's a good sign at least.

What else should I check?

Maybe I should just go ahead and buy that disassembled 401 that's for sale here in town and swap it in...

You should be happy AMC's are not known for having cracked heads. SBC's crack if you even consider over heating them.

When you say a couple minutes, do you mean 20, or 2-3? If it was even less then 10 I think you are fine. I am sure it got hot, but its not under load or the like.

Like you said, check for a blown head gasket. Otherwise you are probably fine.

Maybe 5 minutes. I was doing the initial idle settings after programming the fuel injection. I didn't actually drive anywhere.

derf wrote:Maybe 5 minutes. I was doing the initial idle settings after programming the fuel injection. I didn't actually drive anywhere.

Oh your fine. The engine isnt even fully up to temp yet most likely. The thermostat would most likely just be opening.

No sign of coolant in the oil. But there's plenty of coolant coming out of the heater box in a very slow trickle. I'll swap that out and see how it runs.

You should be good. 5 minutes isn't even enough to warm the cylinders in these heat monsters.

lindel wrote:You should be good. 5 minutes isn't even enough to warm the cylinders in these heat monsters.

It got warm enough to build up steam pressure from the remaining water. Enough to pop the radiator cap off and crack the heater core.

Steam climbs pressure fast. Fill the rad with the heater core replaced or bypassed for now and run it to see if the temp climbs. If not, you're probably OK.

I wouldn't worry about steam. It's like a kettle on the stove. When the steam comes out, the water still hasn't reach it's full boiling potential, and once that pressure is released, a massive amount of heat escapes, slowing the process back down a little. The heater core is thin walled, so it'll blow much faster than the block. Sucks though. That's a pain in the Moogley.

The chambers will see temps around 1200*F, so I'm not surprised that any coolant left in the block would be turned to steam.

That said, the block and hoses are probably up to the task, especially when your "pressure valve" blew.

Running an engine without coolant for a short span (5 minutes) isn't much of a strain on the engine itself.

When you fill the engine with coolant after the heater core change, leave the radiator cap off and allow the engine to "burp". You'll probably see a little overflow during that process, but it shouldn't be much of a concern. Even if you don't do that the trapped air will find it's way out eventually, but you might have hot spots in the mean time.

Sounds good. The heater core should be here today or tomorrow. I'll have it in by the end of the week.

So the new heater core showed up. And it took about 3 seconds for the bottom bracket to fall off, uncovering a shoddy brazing job. :-w

So yea, I get to wait for a couple more days...

At least it broke before installing it

Stuka wrote:At least it broke before installing it

True