Akstraw

Thermo Syphon Cooling

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I have a 1914 Maxwell with 4 cylinder flathead that is designed with "thermo-syphon" cooling.  There is no water pump, and the cooling system is non-pressurized.  The radiator and block both seem very clean and unobstructed.  When I run the car for more than a mile or two, I get a little bit of boil-over, and I hear a mild thumping sound like water boiling (percolating?) in the cooling system.  I had read somewhere once that both of these are normal; that the boil-over is actually the result of the coolant expanding, and the thumping sound is an indication that the system is working correctly.  Is that correct, or is the thumping sound of boiling liquid an indication that the engine is running too hot?  Nowadays, it is easy to measure temperature with one of those standoff IR guns.  What do you think is the 'normal' operating temperature for such an engine on a hot day?  How hot is too hot?

 

I have purchased one of those aftermarket add-on water pumps that was made for a Model T.  It would be easy to adapt it to the Maxwell.  Is this worthwhile to do?  Have any T owners had positive results with this?

 

BTW, I am using a 50/50 mix of Xerex IAT coolant and distilled water.  

 

Andrew

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Andrew, I ran Model T's for 35 years and they also have thermo syphon. When you hear the thumping, it means air is pounding in the system. If so, the efficiency of the thermo syphon is greatly compromised.  If you test the temps in the radiator, top to bottom, there should be a significant difference, maybe 40 degrees or more from top to bottom. You will need an excellent radiator. Remember, the problem, as I see it with thermo syphon is that it normally runs just under boiling, maybe 200 degrees, which does not leave a lot of room. While some may balk at a water pump, I ran pumps on all my T's and concentrated on having fun rather than worry while watching the temperature gauge... If you can modify the T pump, do it...

 

Frank

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I did the same oldford.

I bought a '27 Tudor which over heated from the get-go.

Along with the car came a tool box and in that tool box was a water pump which appeared to be slightly used if not NOS so I installed it.

It worked TOO well so I had to get a thermostat so it would run hot enough........ :o 

Needless to say that was that.

Too many are quick to poo-poo water pumps but not everyone has the $800-$900 it takes to buy a new radiator....... :wacko:

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Saw a number of similar-vintage thermo-syphon cars on car tours during the 1960s, and most of them were heat-challenged. Most of the owners wound up adapting Model T accessory pumps. 

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One of the not often thought of things when cars run hotter than normal is whether the radiator is having trouble with air flow, especially when not a daily driver....

After dark put a light behind the radiator and look in from the front; you may see some clogging from bits of leaves, old spider webs, etc., that may be affecting cooling...

And it's free...

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Thanks, guys.  Will do the radiator inspection as Bud suggested, and go to work on the necessary mods to adapt the T aftermarket pump

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I'll bet you don't ever have to worry about your 1930  making  those noises. 😉

 

Paul

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My Dad restored 2-Cylinder John Deere Tractors for almost 50 years.  As everyone knows Deere used the thermo-syphon cooling system for decades and without problems I might add.  A tractor does not run down the road at 40+ MPH forcing air through the radiator core.  This is just a guess, but, I would lean toward there being some sort of obstruction in the cooling system causing the engine to run hotter than normal.  The physics of thermo-syphon cooling are really quite simple and almost fool-proof if maintained properly.

 

Terry Wiegand

South Hutchinson, Kansas

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Check your timing. Ever slightly too much retard will cause over heating.

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 I have no issue with fitting a water pump, however, it seems to me if you have boil over and hear thumping  after 1 or 2 miles there is a problem that needs identifying and fixing and I doubt a water pump will fix it.  Apart from what has already been mentioned I would make sure that the fan belt is in good condition and properly tensioned.  A check of the head gasket for leaks might be in order as well.

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On June 12, 2019 at 11:23 PM, PFitz said:

I'll bet you don't ever have to worry about your 1930  making  those noises. 😉

 

Paul

How true!

 

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On June 13, 2019 at 7:12 AM, Restorer32 said:

Check your timing. Ever slightly too much retard will cause over heating.

 

Ran for about a mile today at full advance, and after tightening fan belt.  Temp range on radiator with IR  gun was from 180 to 130 top to bottom.  No boiling.  Temp on cylinder wall was 220.  This is encouraging. I plan to try a seven-mile drive next weekend and see how it does.  Thanks for your responses all.  Still may try the water pump, too.

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I get that percolating sound in my '15 T  a little while after shutting the engine off and the fan is therefore not cooling the radiator.   It never boils over while while driving, and I haven't had to add water ever.   I suspect the percolating sound is normal in a shut down engine.

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I did get a slight bit of the percolating sound upon shutdown, but no boil over.  I have one of those big 36" floor fans in my shop.  I suppose parking it in front of that upon shutdown couldn't hurt.

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Don't let some gurgling at shut down bother you.

I'm not sure there's a T that doesn't do it.

Even my '32 Chevy will do it in very warm weather even though it runs in the low medium range ALL the time.

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