7.3 puking coolant

Alright Guys, I've run into a problem I just can't seem to figure out. Last spring I put together and installed a 99 7.3 in a customers truck. Heads were checked and planed, block was honed and new rings and bearings were installed. Motor was completely gone through and rebuilt. Truck ran good when they picked it up. Well 11 months down the road, I get a call saying " the truck is pushing out its coolant". I picked the truck up, brought it to my shop.
5 minutes after start up on a cold engine, the coolant will begin to just pour out of the cap. It seems to be under a good amount of pressure. I immediately though head gasket, but after doing a Block Test several times I've found there to be NO exhaust gas coming through the coolant reservoir so I'm not sure how it could be a head gasket. I replaced the thermostat twice and even tried running the truck without a thermostat just to confirm that wasn't the issue.
The weird part is, after the truck reaches operating temp, the puking stops and the truck runs normal. You can run it as hard as it'll go and it doesn't get hot or puke, runs like a top. There is no coolant in the oil, or oil in the coolant. This problem also is inconsistent, some days it will puke, other days it won't. So does anyone have any idea where else I should look to find the problem? I'm getting ready to rebuild a whole new motor and drop it .

It will puke coolant at idle?

Yes. Just sitting at an idle 2 or 3 minutes after start up, the coolant level will just begin to rise and begin to over flow.

Can you smell fuel in the coolant at all?

No, there is no Fuel in the coolant. There is No cross contamination of fluid anywhere that I can tell.

You've pressurized the engine stone cold? Guessing that's what you mean by block test?
I'd guess a Crack in the head.

Have you pulled water pump ? Put a pressure gauge on it and see if it rises with boost.

Made sure radiator has no restrictions?

I have not pressurized the engine cold, wasn't exactly sure how to go about do it. The block test I was refering to is the chemical test that checks the gases coming from the coolant reservoir to see if there is exhaust gas present. It calls it a block test on the box, so that's what I listed. I should have been more specific. I have not pulled the water pump, but as of last spring it was also new. The heater also works perfectly, so I would think if there was a restriction preventing flow that the heater core would also be plugged. Anyway thanks for the input, I'll pull the water pump today and take a look at it.

Pull each glowplug, and pressurize each cylinder with air, and see where the pressure is going.

That'll be my project for today, I'll get back to you guys and let you know what I find.

Pressure checked the coolant system yet?

Yes, Pressurized the cooling system and found nothing out of the ordinary. Did a few more tests and couldn't seem to find anything out of the ordinary. That doesn't surprise me, because this puking issue is hit or miss. Some times it will puke 2 days in a row and some times it will go 3 days without doing it at all. I yanked the motor yesterday, and pulled the heads. The gaskets seemed to be perfect yet. Hell I had to pry the heads off, so neither head was extremely warped or anything. The only thing I found out of place, was in cylinders 4 and 6 I found a small amount of rust on the bottom side of the head, so moisture was getting in somewhere. Cylinder 4 also had a few marks on the cylinder wall that shows were some coolant had sat in the cylinder for a while. I can't find a noticeable cracks anywhere and everything else looks brand new inside. So the question is, Find a whole new motor and eat the cost OR risk throwing on two new heads with new gaskets and praying it had a head issue?

Petro said:

Yes, Pressurized the cooling system and found nothing out of the ordinary. Did a few more tests and couldn't seem to find anything out of the ordinary. That doesn't surprise me, because this puking issue is hit or miss. Some times it will puke 2 days in a row and some times it will go 3 days without doing it at all. I yanked the motor yesterday, and pulled the heads. The gaskets seemed to be perfect yet. Hell I had to pry the heads off, so neither head was extremely warped or anything. The only thing I found out of place, was in cylinders 4 and 6 I found a small amount of rust on the bottom side of the head, so moisture was getting in somewhere. Cylinder 4 also had a few marks on the cylinder wall that shows were some coolant had sat in the cylinder for a while. I can't find a noticeable cracks anywhere and everything else looks brand new inside. So the question is, Find a whole new motor and eat the cost OR risk throwing on two new heads with new gaskets and praying it had a head issue?

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Find a good drop engine and roll. 75% of issues that pop up like this are on "rebuilds" don't know why that is but just seems to happen that way.

Ya I'm kind of thinking the same the thing. Don't really want to do this for a third time.

If you reuse the block, check it thoroughly for cracks. Seen a few cracked mainly in the bottom end. But it would suck to put new heads on a junk block.

I would think the issue has to be in the head, since only two cylinders show signs of moisture and those two cylinders are side by side. Idk, its a head ache that I could do without.

Results?

What did you find out? My 02 has the exact same symptoms.
Thanks.
Scott

my 53 project had this happening. turned out to be a tiny crack in the injector cup.

It still puked without a thermostat? Did it puke faster with it out? What happens when you run a coolant flush?