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Discussion Starter #1
I'mk driving down the highway anf the engine is running where it should on the temp guage then all of all of a sudden the radiater shoot coolant out the overflow!

The engine was never in the hot zone. It reached about 3/4 max after the incident.

I did discover that the tranny cooling lines are up against the header.
Would that cause the coolant to boil over in the radiater?

Maybe I need a new radiater.

The head gaskets are on right so I know its not that.
 

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...I did discover that the tranny cooling lines are up against the header.
Would that cause the coolant to boil over in the radiater?...
Doubtful, but not a good situation and worthy of correction.

I would recommend a radiator pressure test once the engine is warm and coolant circulating to see if combustion gasses are pressurizing the cooling system beyond the "normal" pressure of 10-15 lbs and causing what you have described. That and/or looking for bubbles in the circulating coolant while wamr and idling with the cap off.
 

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Did you recently add anti-freeze? I have had that happen, but learned I had filled my overflow/catch tank to full. Once it released the excess, well, it never did it again.

Like Lad115 said, try a different cap.

I wish you well, for sure.

Dale in Indy
 

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Discussion Starter #6
New cap, No bubbles in the coolant as it warms and circulates. Maybe it was a burp?

I think I will get a new 3 core aluminum radiator anyway as the one I have maybe an original. Has the FoMoCo stamp on the upper tank.
 

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New cap, No bubbles in the coolant as it warms and circulates. Maybe it was a burp?

I think I will get a new 3 core aluminum radiator anyway as the one I have maybe an original. Has the FoMoCo stamp on the upper tank.
Burp? Have you been feeding the car carbonated gasoline? :buck:
 

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Discussion Starter #8
I was running the cat for a bit and when you rev the motor after its warm and circulating coolant there are some verry small bubbles that come to the surface. Really Small!
I believe that is from the pump cavitation though. At idle it seems fine.
Drove it to work yesterday and all was well. On the wasy home-antifreeze shower!
 

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I've got it ... he used sparkling water (Evian??) to fill the rad with the A'freeze (lol)!! Burps every time!!

I agree with Dale (Smithbrother) ... maybe a bit of air at time of filling.
 

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Check your cap. If you bought the lowest priced/cheapest cap it's possible you got a bad one.

Also, keep an eye on your coolant and those bubbles. You may have a head gasket developing problems, or a cracked chamber, if the cap is okay and the system is burped. (possible without a lot more diagnostics ruling it out of the equation.)

coolant shower isn't normal, and if it burps it shouldn't be doing enough for what I would deem a shower. It's the difference between a coolant burp and coolant puking.
 

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Discussion Starter #11
I'm gonna put it on a CO sniffer tonight and see if and exhaust gases are in the coolant.
I'll take it from there.
 

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Do you have an overflow tank? If you do not the radiator when cold should look to be low. If you fill it full when cold, then it reaches normal operating temp the coolant expands. When it expands it has to go someware out the cap. If you have a overflow tank like in new cars it goes back and forth from the tank, thats why ther is hot cold lines on them. Older car like 67 did not have overflows so the radiator could never stay completly full after it was hot an then cooled back off. New cars with overflow actualy suck the coolant back into the radiator as the engine cools down below operating temps. Without the tank you have no way to replace the displaced coolant from the expantion.
 

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Discussion Starter #14
The thought of having the radiator to full did cross my mind. I will test for hydrocarbons in the radiator tommorow and update
 

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Do a block check and keep it on the radiator for 10 minutes or so to get an accurate test. There might be a cracked head or gasket. But I agree it could be just a cap, you can check those too with a tester. Good luck
 

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Discussion Starter #16
Did a test with a combustion leak detector and all is well! No leak from the cyl to the cooling system-Woot!

Next step is to get an expansion tank, better radiator cap?
Maybe a new radiator.........
We'll see.
 

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Good job on the coolant CO test, should rule out combustion gas getting into cooling system.
 

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Yeah that is kinda goofy Craig...what is the cap pressure rated for? I'd try a different one just for gits -n- shiggles. Don't trust the ones with the release lever on them. Just buy a straight up 15 lb cap. Any chance the thermostat is in upside down? ;>)
 

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Discussion Starter #19
Thermo is in right. Did it myself. The cap is a 13 pounder. I'll try a 15 for grins.
I'm gonna get a new rad anyway!
 
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