Overheating or not

[35 coupe]

I have a 50 F1 with a motor done by Walt Dupont in it and It has run great for 4 years, and here in Pennsylvania it got really cold the other day so I decided to check the radiator for antifreeze, and when I looked could not see any, It was down about a quart, I put some in, left room for expansion, started the truck and without any radiator cap when the heads got hot the fluid overflowed the radiator. The heads were hot,but the thermostat housings and the upper cases were not even warm and I did not see any flow in the radiator. There is no coolant in the oil and it idles good, no moisture coming out exhaust. Bottom hoses are hot. Is it possible to have 2 stuck thermostats. I let it cool and put the radiator cap on and tried again and it started blowing out the overflow. It has a new walker radiator, new cap. 180 thermostats. Thanks.

[40cpe]

[QUOTE=35 coupe;1401191]Is it possible to have 2 stuck thermostats. /QUOTE]

Anything is possible. Remove the thermostats and try it.

[G.M.]

I can see the coolant coming out when you ran it without the cap. The
stats are closed and the coolant couldn't circulate. I don't understand
Why it blew coolant later with the cap on? You should have a pressure
cap so until the coolant got over 210 nothing should be coming out the
over flow. If the pressure cap wasn't sealing just the back pressure of
the stats and slight restriction of the radiator tubes would allow coolant
to come out the over flow. Only other thing would be a compression leak.
I suggest you call Walt before doing anything. G,M,

[35 coupe]

I took out the thermostats and put them in water, 1 opened at 182* and the other never opened.

[flatheadmurre]

Retorq the heads cross your fingers and at it again with new thermostats....
And no water should flow out with cap off when the stats are closed since they restrict flow coming into upper tank, pumps pump cold water into the block not into the radiator.
If it still blows water you have a headgasket issue or worse....

[35 coupe]

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When I pulled the upper hoses off, the thermostat that did not open had anti freeze in the housing and thee hose was filled, the other was drained.

[19Fordy]

This is a long shot, but do you think the impellers on the pumps are defective and even though they turn, they aren't pumping?

[35 coupe]

I thought about that, Thought the thermostats would be an easier fix, so I'm trying them first. I guess the is no way to test them other than removing them from the block.

[Walt Dupont--Me.]

I think the radiator froze up, cover the rad with a blanket, let it run until it gets hot and let it cool down, then do again, it will thaw out the rad, put enough coolant in the rad so it goes to 40 below. Walt Hope it didn't crack the block.