Radiator overflowing ,spurting

[G.M.]

Originally Posted by Voycey

Hi Water spurts ,sometimes, out the cap on the radiator of my 36 when it gets to operating temp , on the gauge, it never seems to overheat, and the temp fluctuates from idle to moving. From previous threads others state the radiator water level will find its own level depending on running temp etc

What is the best way to check that both water pumps are working properly.

Could the spurting be a semi blocked radiator , dodgy cap seal or something more sinister.

Appreciate any help.

This is a problem with engines without pressure caps. First of all this
bolony about water seeking is own level and half filling the top tank is miss information. The system was made to run with 22 quarts of water, less makes it run hotter. The problem is the pumps won't freely push water through the radiator tubes. This is the main reason Ford went to a 4 lb pressure cap. The pressure cap seals at the bottom below the over flow tube and above the tube at the top off the cap. This allows water to be forced through the tubes and in the event of high temperatures above 205 or a compression leak into the water the cap becomes a safety valve releasing pressure. On years like yours with no provision for a pressure cap there is a 3 lb valve made that acts similar to a pressure cap. This valve go's on the bottom of the over flow tube with a small rubber hose and clamps. Also as you as you experienced the radiator cap itself needs a better gasket or water squirts out of the cap seal. A thin piece of red rubber gasket material from the local hardware store, the rivet drilled out and replaced by a 1/4-20 SS screw, lock washer and nut solves that problem. There are well over 1,000 of these in use. After installation fill the radiator almost to the top. The valve is supplied by [email protected]
cost is $28.00 including shipping. You may want to check that your over flow tube is working. With the cap off blow a little low pressure air up through the over flow tube and see that a free flow of air is getting through to the top tank or in the filler neck which ever place the over flow tube comes from. Your symptoms indicate a blocked tube or bad compression leak if the temperature was below 205. G.M.