Temperature Rises after shutdown

Baypac

Baypac

Member
I have been working on getting the 30 CCPU more reliable. It only was driven 1000 miles since 2002. I have 250 miles in two weeks. It idles nicely, and runs at 45 to 55 mph very well.

Outside temperature about 95, after a 20 minute run at 45 to 50 mph, spark fully advanced, the temperature is about 185 to 190. I park it in front of my garage and the temperature will continue to climb until it reaches 212 and it will puke out some water from the overflow. This has happened several times.

Any thoughts?

Jack
 
The syphon cooling system in a Model A is working whether the car is running or not. What is not working is the water pump and radiator fan. Syphon moves about 35 to 36 GPM. Water pump is really only any help at higher speeds.

Are you using a thermostat?

Are you using a temperature gauge or portable temperature gun?

Out flow at the very top of engine, above water pump, should have the warmest coolant. Inflow at bottom of engine/radiator normally would be about 20 degrees cooler than coolant at the out flow, top of engine.

If your temperature readings are correct, I would be concerned about some kind of obstruction that could be restricting the syphon effect.
 
Temp going up on shutdown is not unusual. You may be overfilling the radiator. I filled mine up and it pucked out water, I refilled it again and it did the same so, I let the car set the level of the radiator. I stuck a stick in to see where the liquid level was and it was about and inch above the radiator core! So I left it that way! All is well for me, no pucking and no over heating. let us know what U do!
 
Normal occurrence for the temperature to rise. When you shut off the engine the fan and water pump are no longer turning and water circulation slows while the coolant continues to soak up the heat from the block. Happens in most engines. You just don't see it in your modern because when you shut off the engine you also shut off the temperature gauge... :p
 
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WHN said:
The syphon cooling system in a Model A is working whether the car is running or not. What is not working is the water pump and radiator fan. Syphon moves about 35 to 36 GPM. Water pump is really only any help at higher speeds.

Are you using a thermostat?

Are you using a temperature gauge or portable temperature gun?

Out flow at the very top of engine, above water pump, should have the warmest coolant. Inflow at bottom of engine/radiator normally would be about 20 degrees cooler than coolant at the out flow, top of engine.

If your temperature readings are correct, I would be concerned about some kind of obstruction that could be restricting the syphon effect.
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The truck was set up for touring and I have two thermometers..a motometer on the radiator cap and a temperature probe in the gooseneck. Both are pretty close on the temperature reading. I will leave the water level as is and see if the puking stops.

Thanks,
 
Since it did not run much for a long time, I would flush the radiator and then flush the engine both ways. From the bottom hose up with the radiator disconnected and then down with the bottom hose loose...then flush the radiator...disconnected from the engine. Run water until it runs clear. If you can use a power flush of some sort, take the water pump off and flush the head really well also...then run 50/50 premixed antifreeze...Just my humble opinion...Ernie in Arizona
 
Baypac said:
The truck was set up for touring and I have two thermometers..a motometer on the radiator cap and a temperature probe in the gooseneck. Both are pretty close on the temperature reading. I will leave the water level as is and see if the puking stops.

Thanks,
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Once the engine is shut down, the heat generator is off. Hot spots around the block could cause some increase but the continued syphon effect should take care of most built up heat.

If your running 180 degree thermostats, they might not be fully open until 200 degrees. Water boils at sea level at 212 degrees. The higher above sea level you are, the lower the boiling point of water. The higher your temperature goes the more chance of boiling. Boiling water (now a vapor) in your block will not cool your engine. You need a fluid. Straight water cools better than anti-freeze.

Boiling water within your engine block could also cause oil flash on your cylinder walls and engine failure.
 
I flushed the cooling system with an oxalic acid flush, water was bright green on draining. A fair amount of sludge also came out. Used the sodium bicarbonate neutralizer and drained again. Water was black with a fair amount of sludge. Flushed the radiator.

Filled the system with water and took a test drive. Now it wants to boil over after 15 minutes at 45 mph. Parked and let it cool and could hear the water boiling in the engine. Started to drive home, it heated up immediately to boiling. At a stoplight, it backfired a few times when I started up then nearly died. I pulled into a parking lot and let it cool. Rough check on the timing indicated it might be a little slow but but within adjustment of the spark lever.

Drove it home slowly, still at 212 degrees on the guage and boiling in the engine when I pulled it up to the garage.

The exhaust manifold is pretty hot, and I am thinking that the condenser might be a problem because of the heat. After it cooled, I checked the spark from the coil. Nice strong spark with a little yellow but mostly blue. It will jump 3/4".

Any thoughts....
 
Sounds like the rad tubes need to be rodded. I'm confused as to two thermostats. Are they both installed in the system at the same time?
 
Baypac said:
I flushed the cooling system with an oxalic acid flush, water was bright green on draining. A fair amount of sludge also came out. Used the sodium bicarbonate neutralizer and drained again. Water was black with a fair amount of sludge. Flushed the radiator.

Filled the system with water and took a test drive. Now it wants to boil over after 15 minutes at 45 mph. Parked and let it cool and could hear the water boiling in the engine. Started to drive home, it heated up immediately to boiling. At a stoplight, it backfired a few times when I started up then nearly died. I pulled into a parking lot and let it cool. Rough check on the timing indicated it might be a little slow but but within adjustment of the spark lever.

Drove it home slowly, still at 212 degrees on the guage and boiling in the engine when I pulled it up to the garage.

The exhaust manifold is pretty hot, and I am thinking that the condenser might be a problem because of the heat. After it cooled, I checked the spark from the coil. Nice strong spark with a little yellow but mostly blue. It will jump 3/4".

Any thoughts....
Click to expand...

You should Google “Rocky Mountain Model A Club Cooling Presentation”. Read it.

Take out those thermostats.
 
gustafson said:
"the temperature is about 185 to 190"


Your baseline temp is too high to start with. Why are you running full advance
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I always understood that the engine ran cooler with advanced spark. I with this engine, it runs smoothest when it is advanced.
 
Tacoma Bob said:
Sounds like the rad tubes need to be rodded. I'm confused as to two thermostats. Are they both installed in the system at the same time?
Click to expand...

I must have used the wrong words. There are no thermostats...only thermometers. One on the dash and one one the motometer,
 
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Baypac said:
I must have used the wrong words. There are no thermostats...only thermometers. One on the dash and one one the motometer,
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I hate to be the bearer of bad news but you have a plugged radiator do you either have to get a queen or get another one been through all that ended up with new radiator took care of the problem I have a 160 degree thermostat my temp gauge runs right at 130 degrees in the hottest of weather

Sent from my SM-J700T using Tapatalk
 
michael a said:
I hate to be the bearer of bad news but you have a plugged radiator do you either have to get a queen or get another one been through all that ended up with new radiator took care of the problem I have a 160 degree thermostat my temp gauge runs right at 130 degrees in the hottest of weather

Sent from my SM-J700T using Tapatalk
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I'm sorry that's supposed to say clean Siri is having her way with me tonight

Sent from my SM-J700T using Tapatalk
 
By running the cleaner, you likely dislodged a bunch of crud into the radiator and thats why it got worse instead of better. I would say flush, flush, flush then install a filter/screen in the radiator top hose and run it. Clean the filter often until it stays clean. Probably the crud is loose in the radiator so flushing it should get it out without needing to rod it. I would DEFINITELY run 50/50 antifreeze, there is enough flaking cast iron in an A engine, you don't need to cause more by running straight water.
 
A rise in temp after a shut down, is quite normal.
It's like us, we run & the breeze cools us. We screech to a halt & say, "GEEZ, I'm HOT, UR you HOT"?
Bill Can'trun
 
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