The Ford Barn

jack99 · 11-01-2020, 03:46 PM

I have a 1935 Ford with the 221 engine. What causes the radiator to syphon to the overflow tube when the engine reaches normal temperature?
Any thoughts? Thanks

FlatheadTed · 11-01-2020, 04:39 PM

If you over fill it will flow out until it finds it comfortable high 2" downs about right ,if it goes lower you have a problem Gasket or blocked core ,Ted

JWL · 11-01-2020, 07:02 PM

Ted hit the most obvious problem--if the coolant cannot pass through the cores with adequate flow rates the top tank will fill and actually become slightly pressurized and coolant will be expelled out the overflow.

G.M. · 11-01-2020, 10:22 PM

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This happens as the engine cools. As the temp drops threw
155 degrees there is a vacume in the engine and the coolant
is sucked from the coolant overflow bottle back into the
radiator. You need a 2 to 4 lb pressure cap and an overflow
bottle for this to work. G.M.

11-01-2020, 03:46 PM	#1
jack99 Senior Member Join Date: May 2010 Location: Bridgehampton, NY Posts: 125	Radiator Syphon I have a 1935 Ford with the 221 engine. What causes the radiator to syphon to the overflow tube when the engine reaches normal temperature? Any thoughts? Thanks

11-01-2020, 04:39 PM	#2
FlatheadTed Senior Member Join Date: May 2010 Location: Auckland Posts: 4,700	Re: Radiator Syphon If you over fill it will flow out until it finds it comfortable high 2" downs about right ,if it goes lower you have a problem Gasket or blocked core ,Ted __________________ http://www.flatheadted.com Flathead Ted brake Floaters ,

11-01-2020, 07:02 PM	#3
JWL Member Emeritus Join Date: May 2010 Location: Fitzgerald, Georgia Posts: 2,204	Re: Radiator Syphon Ted hit the most obvious problem--if the coolant cannot pass through the cores with adequate flow rates the top tank will fill and actually become slightly pressurized and coolant will be expelled out the overflow.

11-01-2020, 10:22 PM	#4
G.M. Senior Member Join Date: May 2010 Location: Florida and Penna. Posts: 4,471	Re: Radiator Syphon Sponsored Links (Register now to hide all advertisements) This happens as the engine cools. As the temp drops threw 155 degrees there is a vacume in the engine and the coolant is sucked from the coolant overflow bottle back into the radiator. You need a 2 to 4 lb pressure cap and an overflow bottle for this to work. G.M. __________________ www.fordcollector.com