While doing the fuel line mod, I broke a hose clamp on the hose between the water pump and head. I decided to replace all the heater hoses. Needless to say, I lost at least a half-gallon of coolant in that process. However, the radiator was still full. So I added new coolant to the overflow bottle, almost to the top. Today when I got to work (about a 6 mile drive, 15 minutes in town traffic), the temp gauge was almost pegged high (normally the needle is at about 11 o'clock). The overflow bottle was still full. What is wrong?

If it makes any difference, the overflow bottle has been only partly filled the whole time I've had the car until now.

Does the radiator cap have a rubber gasket for both sealing surfaces on the radiator neck? (inner hole and top)

It also usually takes a few heat cycles to get the siphon going.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

When I went out to the car this afternoon the overflow bottle was empty, the radiator was full, and the engine didn't overheat on the way home. I guess this morning when I parked, the thermostat was open but the head was still filling. After I parked, the radiator must have continued draining into the head through the still-open thermostat, and at the same time siphoning from the overflow. It's funny to think that happens when the engine is not running, but then gravity never sleeps.

When the coolant cools off, it 'shrinks' creating a slight vacuum to pull fluid from the bottle.

-Matt

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-MattMan
LEANED & MEAN