Overheating 1930 Model A Ford Coupe

[Big Dan]

I have an original radiator which I have flushed and back flushed (several times), but still have an over heating problem. Checked and head gasket appears OK; compression runs about 55 per cylinder & no bubbles in radiator. Checked timing & is OK. Runs on the road 35 to 40 with no overheating, but checked temp & it is above 205, but not boiling over. Boils over if I push her 45 to 50. I'm considering a new radiator; Brassworks extreme touring 11 FPI or Brassworks Active driver 10 FPI. I'm confused whether I need to add a fan shroud &/or one way check valve. Also do I need to add a thermostat & if so how do I install it? Any suggestions would be appreciated. Big Dan

[Marshall V. Daut]

Do you have a split radiator cap, such as a Moto-Meter or a Flying Quail? If so, when the coolant in the radiator is pushed at high speeds, it flows faster through the top radiator tank than the core can handle. This excess water then forces its way through the most convenient and easy exit place, meaning between the two halves of the specialty radiator caps. The engine is not overheating; it's just pumping out the heated and expanding water. This is a very common situation that is usually attributed to engine overheating.
Place a standard plain radiator cap on the radiator instead of the specialty two-piece cap and see if that stops the coolant exit. Also, do not overfill the top radiator tank. Only fill the top tank until the water is just above the core. More than that and the heated coolant will find a way to exit.
Marshall

[nkaminar]

The original radiators can loose contact between the tubes and the fins. Over the years the thermal expansion and contraction cause the fins to loose contact. No contact, or very little contact, means that the thermal transfer between the tubes and the fins is bad. You can re fin the radiator or buy a new one. Probably about the same cost.

[Gary WA]

Have your radiator professionally cleaned and rodded out!!

[old ugly]

how full are you filling the rad. same as Marshall V. Daut said.

the level should be just above the tubes. or. once the coolant expands it will burp out of the cap or out the overflow tube.

my brother phoned me up. said my A is continually puking coolant out on the ground, i have to ad to it every time i go out. he was filling it to the top before every trip.

if the coolant level is correct and its boiling then its back to our regular programing.

OU

[stevemclark]

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I had the same thing, radiator was original and did not leak.I had it rodded out and tested but it still overheated.The guy at the shop said it was 95 years old and missing a lot of fins. I bought a Brassworks one pressurized and added an overflow tank, no more overheating.You can still use your motometer on the dummy neck,it will work pour a little coolant in it.The pressure cap is under the hood out of sight.It cost over $1000 but they make them here in the USA.Fit was perfect. https://www.thebrassworks.net/

[Marshall V. Daut]

I still think the OP has to determine whether the engine is actually overheating or whether the coolant is just escaping from beneath the radiator cap. The answer to each will dictate corrective action. Not hard to determine if the engine is overheating, not just overflowing. Is it sizzling? Is it huffing? Does it smell like it's overheating? First things first or else we'll be chasing our tails with suggestions that might not even apply.
Marshall

[nkaminar]

The original poster said 205 F at lower speeds and boiling over if pushed. So it is an overheating problem, not an over fill problem.

[Synchro909]

Originally Posted by Marshall V. Daut

Do you have a split radiator cap, such as a Moto-Meter or a Flying Quail? If so, when the coolant in the radiator is pushed at high speeds, it flows faster through the top radiator tank than the core can handle. This excess water then forces its way through the most convenient and easy exit place, meaning between the two halves of the specialty radiator caps. The engine is not overheating; it's just pumping out the heated and expanding water. This is a very common situation that is usually attributed to engine overheating.
Place a standard plain radiator cap on the radiator instead of the specialty two-piece cap and see if that stops the coolant exit. Also, do not overfill the top radiator tank. Only fill the top tank until the water is just above the core. More than that and the heated coolant will find a way to exit.
Marshall

Unless the volume of the coolant is increased by say, exhaust gasses or steam, the only water that can flow though the top tank comes from the engine, which in turn gets its water from the bottom of the radiator.
In other words, because the volume of coolant is constant it is not possible for the pump to put more water into the top tank than has been drawn through the radiator core.

[katy]

Are you sure that your temperature gauge is accurate?