Coolant pushed out overflow tube - more when revving. Explanations?

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230
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Ca
Went to look at a 1972 Ford Econoline Van. The engine is either the 351 or 302 (owner unsure, in 72 it would I believe it would have been a 302, but may have been changed.) A previous owner had it converted to fuel-injection using an FiTech kit. Started fine, seemed to run well. Did a low speed test dive around the neighborhood, and idled it, probably on 15-20 minutes total run time. Noticed coolant coming out of the overflow tube (there is no overflow tank). When I revved the van, the amount increased. I repeated this cycle a few times. There is a digital temperature display with the fuel-injection kit, and it showed the temp in the 166-172 range. I checked the radiator about 15 minutes after shut-off. Coolant level was to the top. I had checked the coolant before when it was completely cold, and the level had been about an inch lower. Coolant looks clean. There was some debris, but didn't look like oil. Looked to be some old radiator gunk (radiator is old). So, are there explanations for this other than a head-gasket? Or does that seem the most likely?
 
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2,176
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missouri
The older cars needed about at least an inch of air in the tank, 2 to 4 inches is cross flow radiator, to allow for expansion. If it seeks it's level, it is probably OK. Rod
 
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3,392
Location
USA
Engine cold, open the radiator cap to release any pressure then replace it. Squeeze the top radiator hose to feel the pressure inside. Start the engine and rev it and feel for pressure again. If pressure builds up before the engine significantly warms up, blown head gasket. It is easy to retrofit an expansion tank like newer cars had-- that mod is worth doing.
 
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102
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NW, GB
Originally Posted by mk378
Engine cold, open the radiator cap to release any pressure then replace it. Squeeze the top radiator hose to feel the pressure inside. Start the engine and rev it and feel for pressure again. If pressure builds up before the engine significantly warms up, blown head gasket. It is easy to retrofit an expansion tank like newer cars had-- that mod is worth doing.
Do not confuse Expansion vessel with Overflow vessel. They both might replenish the main system on cooldown but are totally different.
 
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3,392
Location
USA
Yes there are two versions of the plastic coolant tank. I think the official name of the system introduced in the late 70's and almost immediately used by all manufacturers, where the radiator cap regulates flow in and out of the tank, is a "recovery" tank. The tank is not under pressure. Much newer cars went to having the whole tank under pressure at the top of the system. Usually there is no radiator cap at all. The coolant expands into the air space in the top of the tank like it would with the air space in the top of the radiator of a car with no tank.
 
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1,193
Location
Arizona
An atypical issue i once had is the vacuum advance diaphragm had a very tiny leak so timing was not getting to normal advance. The symptom was that after driving a bit then stopping at light the overflow would dump some coolant. Found it by pilling a vacuum on it and seeing it slowly drop.
 

OceanRuns

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230
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Ca
Is there anything else that could reasonably cause coolant to come out the overflow tube at a faster rate when revving than when idling?
 
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