305 V6 Coolant not circulating

[jneidig]

I have a 1965 with a 305E that has 64,000 original miles on it. When I bought the truck about 2 years ago, I ran the engine and found that it was overheating and pushing coolant out of the radiator like a blown head gasket. To make a long story short, I found the head gasket leaking at cylinder #2, I believe the head bolts were somewhat loose. After checking the heads and block decks for flatness I reassembled the engine with new head gaskets, cylinder head bolts, water pump and 180 degree thermostat, I also installed a new radiator. I am putting the truck back together from the frame up and I got to the point of running the engine today and it is overheating and not circulating coolant. The top tank of the radiator is getting hot when the thermostat opened but there is no flow though the radiator as the lower tank and hose is at room temperature. Is there something I am missing? I checked and thermostat is in correctly but I didn't test it for operation yet. Just wanted to see if anyone else has run into this on a 305.

[Ed Snyder]

Originally Posted by jneidig

I have a 1965 with a 305E that has 64,000 original miles on it. When I bought the truck about 2 years ago, I ran the engine and found that it was overheating and pushing coolant out of the radiator like a blown head gasket. To make a long story short, I found the head gasket leaking at cylinder #2, I believe the head bolts were somewhat loose. After checking the heads and block decks for flatness I reassembled the engine with new head gaskets, cylinder head bolts, water pump and 180 degree thermostat, I also installed a new radiator. I am putting the truck back together from the frame up and I got to the point of running the engine today and it is overheating and not circulating coolant. The top tank of the radiator is getting hot when the thermostat opened but there is no flow though the radiator as the lower tank and hose is at room temperature. Is there something I am missing? I checked and thermostat is in correctly but I didn't test it for operation yet. Just wanted to see if anyone else has run into this on a 305.

A previous owner could have been using hard water in the cooling system, leading to extensive mineral build-up blocking coolant flow.

[jneidig]

Thanks for the reply Ed. When I had the heads off I removed the freeze plugs and steam cleaned the block out really well as it was somewhat cruddy.
Anyway I have good news, I pulled and checked the thermostat and found that it was only opening about a 1/32 of an inch at 185 degrees (Brand new NAPA stat) made in you know where. Anyways, I replaced it and refilled works great now. It took a little more coolant when I filled it back up so I may have been fighting some air in the system also.

Have a good one!