MTFCA Forum

We have a 1915 touring car new radiator a high head flushed block & a water pump. Runs cool but when you turn it off the car boils over what is left to do

Are you sure you need the water pump? Perhaps the stationary pump impeller is blocking the natural thermosiphon circulation of the coolant after the engine is shut off.

If you mean water is coming out the over fill tube, then maybe you are trying to run with too much water. It only needs to cover the top of the core by about an inch. If you are talking about the radiator gurgling on shut down, that is normal and sounds like the impeller is not stopping the normal flow path of the water as the car cools down.

I wholeheartedly agree with Mark. As long as the engine is running and the pump is pumping everything is fine. When you shut off the engine the thermosiphon system would ordinarily continue to work until the engine cools down. The not moving pump prevents this proper operation.

Take the pump off and use it for a paper weight.

My $0.02 worth.

Your car is trying to tell you, you Are you trying to keep the coolant level too high. Try a 1/4 to a 1/3 down to allow for movement and expansion. The automobile will find the level that suits it. And I too am betting the pump isn’t all it’s cracked up to be.

We have had this problem from the start we let the radiator seek its level we installed a tall head & then we put on a water pump but still have the same problem

if the coolant is ga-lumping and coming out the overflow after turning off, it is too full

if the water is ga-lumping after turning off, but not coming out the overflow, it is normal

the coolant is still trying to absorb latent heat, is rising through the block and will naturally spill over into the radiator where it will cool and sink. Be thankful that your system is working efficiently. With a new radiatior and flushed block, the waterpump is making YOU feel good, not the engine...when not running, the impeller is an impediment to water flow during the post-run cool down period. That said, I am not anti-waterpump, as I have one on a car with an inefficient radiator and it has saved me the cost of a new radiator, so they have their place...conversely, I ALWAYS remove the pump immediately after purchasing a car and have found the vast majority of them did NOT need it, though this ONE car did and I am perfectly fine with that idea.

I would suggest that you are running with spark retarded or too lean or both. I don't think the water level or the water pump has anything to do with it. The only time my 26 with a water pump gurgled over was when I want up a 2 mile grade in low gear and I had my licence plate attached to the light bar that blocked 10% of my radiator. I relocated the plate and no further coolant issues. I ascended the same grade with a full load of people, it took about 15 minutes, and no boiling or gurgling when turned off. Try full advance and a little bit richer.

I have 2 26's and both have license plates on the headlight bar. They both have high heads and no water pumps. Both have Brassworks radiators. I live on a mountain and it is uphill for 15 miles to our town then the last mile toward our house is a low gear or low Ruckstell hill. On a hot day, I pull the hill and the Motometer does not go over "normal summer temperature". When I turn off the engine, it gurgles for a few seconds. It does not steam or pour water out of the overflow. I use 50-50 antifreeze coolant. I fill to the level of the Ford on the front of the radiator shell. If you overfill, it might put out some water when it gurgles but should stop overflowing when it is about 2 inches below the top of the radiator. Do not add water unless it is below the Ford emblem. Just check to be sure it is about half way up the top tank. Wiggle the car a bit to be sure what you see is actually water and not just a wet baffle in the top tank. When I got one of the cars I had a water pump on it. It actually ran too cold and on a cold day the engine would not warm up with the pump. I took it off and the car runs fine just as Henry intended. Same thing with my 22 except it has a low radiator and the license is mounted below the radiator.
Norm

I have a '17 with a new Bergs radiator and a high head. When I initially filled the radiator I had some coolant barf out but once it reached it's level I've lost no more fluid. The car runs cool, even on 90° days. The temperature indicated by the motometer rises after shutdown but again, it doesn't lose fluid.

I agree with many of the comments you've received. I also wonder if you need the water pump and if the impellers are interfering with passive coolant circulation. One other thing - to me, a water pump represents a potential source of failure...there is some comfort in having fewer things that can go wrong.

Has the engine had any work done on it such as removing the head or etc?
If it hasn’t in a while or since you’ve had it the water passages in the block and head could be partially blocked with rust or scale.
If you choose to remove the head to check it you can carefully use a 1/4 “ drill bit to drill out the small holes in the block and head. You can also use an old speedometer cable in the larger passages to help remove the scale.
If it’s a 15 it probably had the engine gone through by now but that could have been years ago.
If it had the water pump on it when you got it that’s a hint there may have been a cooling issue with it in some way. Good luck.

------------- Heresy Alert! -------------- Heresy Alert! ---------------

It wouldn't be pretty, but if your car has already been converted to a starter, generator and battery there are inline electric water pumps used on some newer cars. They're all designed to work on 12 volts negative ground of course, but you might be able to get enough flow for a Model T on 6 volts. You could put it on a switch (with a relay) to turn the pump on and off. That way you could let the pump run for a little while after you shut the engine off and it would maintain coolant circulation.

Do a Google search on "inline electric automotive water pump" and several options will show up.

Rjackson wrote: ↑

Tue Jun 09, 2020 11:02 am

.... Runs cool but when you turn it off the car boils over ...

As someone else has noted: do you mean water comes out of the overflow tube or radiator cap? Almost all Model T "water pumps" don't pump; all they can do is assist in circulating (splash is a better term) fluid by use of finned impellers or propellers within a housing. The impellers are in a cavity much larger than themselves - can't really see how a blockage could occur since they don't cover either their inlet or outlet ports and are smaller than the cavity they are enclosed in. Here's my 2 cents - If the pump/cirulator was the cause of a blockage and the thermal siphon action of the hot engine would continue until a temperature equilibrium was reached, only the water in the head could continue to flow into the upper radiator tank. Then if the water volume in the head was more than the unused capacity of the upper tank when the engine was off there would be an overflow. So how full do you fill the radiator?

Even if taboo and my post out of place, would you post a pic of your pump Ron? Perhaps the guys will have more info to go by.
I have a crappy pump on my wore out Crappy 24 Runabout with an OLD radiator and that particular pump doesn't impede water flow when shut down.
Never a gurgle. Even after parades in the heat. This pump was so not popular (low production), I've only seen one or two pics here.
Very interesting conversation! Thank you for bringing this up.