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1929 Desoto K engine


Wes Rinella
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I have a 1929 Fargo with a Desoto K 6 cyl engine.  The engine was completely rebuilt a long time ago.  I have always experienced Radiator problems.  When the engine warms up it runs at around 175 degrees.  The radiator cap is holding tight but I get a 1/2 a pint or so running out the overflow tube when the engine is turned off. After a few short runs water/antifreeze exits the radiator via the tube inside the radiator when I stop.  I am constantly needing to add water to the system daily after just a few runs.  Question can I block off the tube so water stays in the radiator?  The tube can be seen when you remove the cap.  It is inside the radiator about 3/8 in. from the cap. The only other solution I thought to try, short of capping it off, would be to raise the tube higher in the radiator to bleed off less water.  I can hear water bubbling in the system when the engine is turned off and then it overflows out the tube.  Modern radiators have the tube installed in the side of the radiator inlet and the cap has a pressure release seal  that must be opened at a set pressure before the water is allowed to run out of the system.  My cap is just a flat cap.  No way to prevent overflow at any pressure.  I had the radiator core replaced.  Maybe they installed the tube wrong?  Temp checked with a laser temp gauge.  New thermostat changed twice to see if one was defective.  I'm assuming 175 is a ok running temp on a warm to hot day.  Wouldn't know how to get the engine to run cooler.  Internal timing is right engine and cooling system is clear and recently flushed.  Any suggestions, greatly appreciated.  Wes

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If you don't leave enough airspace at the top, it will push out the water that it doesn't want. Does it continue to get lower if you don't add water? If not, I would leave it alone.

 

It is possible to have an overflow tank on an open system like yours. Chevrolet (and probably everybody else) used to offer them as accessories. It would usually be mounted high, probably on the firewall. Coolant goes up, and then siphons or drains back in when the car cools. The system is still not pressurized, and the vent is at the overflow tank.

 

Don't plug it. Hydraulic pressure will likely break something if you do.

 

In most radiators, the coolant should just barely cover the top of the tubes.

Edited by Bloo (see edit history)
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Thanks for the info.  If I don't keep adding water it keeps draining until the engine temp goes up to 220+ and continues to push out water and gain heat.  it will drop the coolant level well below the top of the fins and pushes out more water as the temp increases.  I don't know what is happening first..overheating for some unknown reason or overheating due to water discharge while driving.  I thought of adding a overflow tank but if the engine was designed to work without one I'm thinking something is wrong with the set up.  I'd pull the head, check the gasket, but there's no water in the oil or oil in the water. Just seams to run too hot. Help!

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You can easily check a thermostat by heating it in water with a thermometer and observing when it opens. By the way, does the thermostat actually get hot enough to open? If it has no hole in it, there could be an air bubble under it, preventing it getting hot enough to open. I drilled a wee hole in mine (ca 2.5 mm). I noted the housing above the thermostat was not getting hot.

 

It sounds like you have a very similar overheating problem to me at the moment. The radiator is clean but it still boils through and ejects coolant.

 

Is the block clean inside? Mine had a bit of cemented muck in the back of the engine. I am nearly ready to try another run.

 

What is the condition of the water pump?

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The water pump is not leaking.  Everything looks right.  I can't think of a way for air to be entering the system other than the overflow tube itself.  Timing it right by sound and feel.  I've never timed it using the old mechanical method and there is no  mark on the damper/pully.  It dumps out 2 quarts if I drive it  10 miles of stop and go.    I'm going to install a overflow tank and see if I can recover  the coolant  so it can  suck back into the radiator as it cools.  If that doesn't work I will pull the head and  check/replace gaskets,  hoses, and anything I can think of.  Thanks for the advice.

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I had a similar problem found out at sometime some one removed or did not reinstall a baffle on the top tank. The upper hose would send the water right up to the cap area my guy put a baffle or a deflector in so the water was forced to go down the radiator core end of problem .Mike

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To check the timing with a timing light, you need to make a TDC mark on the balancer of the crank.

Turn the engine by hand so that the distributor rotor is pointing to #1 spark plug on the cap, unscrew the plug above cylinder #6 (yes, #6) and using a depth gage of your vernier caliper (you could use anything really) find TDC. Then mark a spot on your balancer as TDC, then attach a heavy stiff wire to the engine or body,  the other end of the wire pointing to the TDC mark on your balancer. This will give you a fairly good idea of where your timing is.

 

As keiser said, it could be bad timing that is causing your over heating issues. Or, coolant flow. Its unlikely air in the coolant because there doesn't look like much foaming in your pic.

Edited by maok
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Blocked radiator??  

 

Or - when the engine was 'rebuilt', was it completely stripped, and had all of the gunk removed from the water passages? 

 

If it was done 'a long time ago' has it sat and accumulated more gunk in it. That gunk will now be blocking the radiator.

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Back in the 1960s, we had a '29 Desoto with rebuilt engine and radiator that still ran hot. Eventually determined that the water pump was forcing water through the radiator so fast that the water wasn't there long enough to cool down. My dad put a round block of wood with a half-inch hole in the center into the radiator hose, creating a restriction that slowed the water down and solved the heating problem. I suspect that a thermostat would have served the same function. The possibility of too-fast water flow might also relate to Mikefit's suggestion above that you may need a baffle.

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Thanks to everyone for the great suggestions.   I've cleaned the system and ran it without a thermostat   It overheated badly.  When I put min a new Thermostat it ran cooler but still pushes out fluid more than it should.  I like the baffle idea and will consider the water pump pressure.  I noticed the lower radiator hose does not have a spring inside and it tends to collapse at the bend, more so after shutting off the engine.  I replaced the hoses and installed a internal spring.  Looks much better.  I sent the carb out for repair so I won't know if that helped for a few weeks.  Thanks again for all the input.  I'll try almost anything!

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I would have thought a 1929 engine would not have curved radiator hoses. They didn't know how. No wonder it collapses.

 

Mine has a short straight piece, then a metal bend (90o) then another short straight to the water pump. I found a modern bent hose to fit on mine at one stage, it was from a 4 cylinder Holden of about 1982. Cut off the return bend and the rest of it fitted perfectly.

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