Temperature Rises after shutdown

Y-Blockhead said:
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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I'vce read all of the posts so far and this is the only one to tell what is happening.
What you have observed happens in every engine when it is turned off and always has. That said, I think your running temp is a little high so that the rise that happens after shut down takes yiou past the boiling point. Antifreeze also raises the boiling point of the coolant. If you're not running any, your problem about overflow might be history just by adding antifreeze. I'd verify that your radiator is up to scratch too.
 
I agree with Eagle, when you flushed the engine it caused rust and other garbage to loosen up. I recently took a car for a ride that had been sitting for a while and had the same problem. The top hose was boiling hot with steaming water coming out the overflow. The lower water hose and pipe were barely warm.
Remove the top and bottom hoses, Take a flexible radiator hose and connect it to the lower outlet on the radiator. Now take a garden hose and plug it into the hose and seal it up with a rag. Turn on the water and watch all the junk come out the top inlet. Do this for a while and you might save a few bucks getting the radiator flushed at a shop.
 
In the past, we've established that the OLD IRON in the blocks & head are just a "FACTORY" producing RUST FLAKES. They end up stuck in the top of the radiator & lessen the efficiency of the radiator. Back flushing the system once or twice a year helps.
Another culprit is a system filled with greasy scum. That can be cleaned with your favorite, NON-FOAMING detergent. T.S.P. or even dishwasher soap will work.
Overheating is NOT a problem, with a decent radiator & NO head gasket combustion leaks. Combustion leaks can even be detected, by smelling the radiator filler neck!
Hope this helps.
Bill Cool
 
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It seems to me that everyone is saying the same thing just in different ways.

Bottom line here as I see it. There is some type of obstruction, most likely a bad radiator.

The Model A cooling system is a very simple operating system. Thermal syphon. Hot water up and out, cooler water down and in. Syphon starts at around 180 degrees. Water coming in at bottom of radiator should be about 20 degrees cooler, 160 degrees. Normal operating temperature for a well running Model A engine is in the range of 170 plus degrees, with some hotter spots.

Once engine is turned off engine will stop making heat. Syphon cooling system will continue to work until water/coolant cools to a level point.

Hot spots in engine are only places that should/could increase heat once engine has been shutdown. There is nothing in a normally running engine that will cause the coolant to boil once your engine has been shut down. It was boiling before, while running, somewhere inside the block.

I would not keep running that engine. Needs service. Radiator, engine block flushing, checking of water pump, anything that could restrict the coolant flow must be checked.

Again. Very “simple” system! You don’t have to be a rocket scientist to understand how it works. The Model T used the same system but without the water pump. No moving parts.
 
Thanks to all. I have been driving Model A's on and off for 60 years, and never heard one boil inside the engine when it shut down when it still had water. It is not because my hearing is better now. Maybe it was because I had too many other things to do when I was 16 and did not stand and listen. Also, I never had a thermometer in the goose neck before, so did not see the water temperature rise when it was shut down.

The engine is running too hot so I will experiment with the GAV and the spark advance to see if that helps. Will also back flush engine block and radiator separately with a garden hose until the water is clear. I will also switch to antifreeze to get a higher boiling point mixture. I will keep you posted on results.

Jack
 
Baypac said:
Thanks to all. I have been driving Model A's on and off for 60 years, and never heard one boil inside the engine when it shut down when it still had water. It is not because my hearing is better now. Maybe it was because I had too many other things to do when I was 16 and did not stand and listen. Also, I never had a thermometer in the goose neck before, so did not see the water temperature rise when it was shut down.

The engine is running too hot so I will experiment with the GAV and the spark advance to see if that helps. Will also back flush engine block and radiator separately with a garden hose until the water is clear. I will also switch to antifreeze to get a higher boiling point mixture. I will keep you posted on results.

Jack
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Distilled water with a rust inhibitor has better cooling properties than anti freeze or a combination of anti freeze and water. If your looking for just the best coolant, than water is the answer. If you also need freeze protection, than you need anti freeze.

A higher boiling point will just let your engine get hotter before it starts to boil. That does not even start solving your problem. Engine should be running within normal operating range, 165-175 degrees.

There are owners who will say their engine needs to run hotter. I wonder if 90 years from now these hotter running engines will still be in use?

Heat can be your engines biggest enemy. Sorry I got my soap box out. Enjoy.
 
old31 said:
I thought that 185-190 is a perfect temp?
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It is. Eagle has it right in #18.
I'd remove the radiator, turn it upside down and flush it by using a sump pump. I've posted pictures of the whole job here before, and a search should turn them up.
 
A large sump pump makes a good flushing pump for a lot of things because it has such a high volume. A garden hose is really not enough volume.
 
Tom, it is boiling before he shuts it off
With a clean block and good radiator here we never go over 180 (no stat) even in summer.
That tells me the design temp is not more than 180
 
I had the same problem. You could hear the water boiling in the engine when I shut it down. I tried back flushing, front flushing, TSP, Cascade, Rust 911, left vinegar in Radiator out of the car for 1 month. Nothing helped. I finally bit the bullet and bought a new Heavy Duty radiator from Brattons. It fit great and my temperature doesn't go over 170 even on 95 degree days just idling through the neighborhood for 30 min.
 
gustafson said:
Tom, it is boiling before he shuts it off
With a clean block and good radiator here we never go over 180 (no stat) even in summer.
That tells me the design temp is not more than 180
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I like any temp from 180 to 195. Once I got the junk out of my block and back flushed the block and radiator, the car runs fine now. I have a 175 or 180 thermostat in the top hose.
 
I just installed a 180 tstat because my new Bergs Radiator and new engine had a hard time going above 160-165 on a 92 degree day running at 60 mph for a long run.

I now get it up to 180 real fast,I will appreciate this more in the cooler months with the manifold heater.

Now it stays at 180-190, and when I shut it off it goes to 210.
 
Update on Engine overheating. I flushed the system and refilled with 2 gallons of evapo-rust and half a gallon of distilled water. Idled it until hot then shut it down. Drove it about the neighborhood for 20 minutes, and let it sit over night.Took another drive to the store and then shut it down.

After 36 hours, drained the radiator. The evapo rust was dark black with some fine suspended particles. Flushed the radiator and filled with distilled water and drove it for 3O minutes at 45 mph with a top temperature of 180 degrees. Adjusted the GAV to run richer and also reduced the spark advance to 3/4 of the range. I think there were two problems in addition to the rust...running too lean and too much spark advance.

Either I need training or the carb needs some work. It runs really well at idle and power when the engine is cold. Once it heats up, the idle is still OK with retarded spark, but the engine lopes at stop lights unless I retard the spark. Some work on the GAV may also be of help.

Thanks for the help.
 
Yeah, I chased cooling issues too, not wanting to replace the radiator. But high road temps here in SoCal already reduce cooling a bit.
While increases in temp. after shutting down is common in all cars (this is one reason modern pressurized system have recovery reservoirs ). If it boils over you’re probably running hot anyway. Check the usual, timing, head gaskets, mixture etc. But when i’d done all that I ended up replacing the radiator. Problem solved. Now on the hottest day I can climb hills, race around or whatever without worrying. Bigger margin with new clean radiator. Also, as the Rocky Mountain article notes, there is some evidence that running antifreeze in unpressurized systems actually lowers the cooling efficiency (or maybe boiling point. Cant remember. Been a while.).
 
Thanks to all for suggestions and ideas. I have about a 20 mile round trip into town, and have to drive 45 mph for much of it to keep the other drivers from running up my tailpipe.

Now running distilled water with water wetter. Increased GAV to half a turn. Checked the plugs and found more carbon than I like, so have been running with it 1/4 turn open. Reduced the advance a little, but adjust based on engine sound to maximize power on hills.

It still idles at count the strokes speed when hot or cold with the spark fully retarded. It idles well when the temperature is below 185 but lopes at stoplights when the temperature is above that level.

No more boil over, but the engine runs hotter than I would like. I would prefer 180 to 185 maximum. Now, it heats up to 180 to 185 after 10 to 15 minutes, but at stop lights the temperature increases to 190 and pushes 200 sometimes. Will cool down to 190 - 195 when driving at speed.

I have a 6:1 Snyder Head that I plan to install. I understand that engines with the high compression heads run cooler than with a standard head.

Can anyone give me an idea of how much cooler the engine might run with the Snyder Head?
 
Is your radiator a 2 row core or a 3 row core? If a 2 row you could be fighting a losing battle. If it does work it may barely work. If you are marginally OK, water wetter and GAV/Advance settings help, but to me it seems something more major is occurring.


A sign of rust in the system and/or not enough radiator cooling capacity is over heating above 40 mph with 80 degree temps and above. If you have a motor coolant outlet temp gauge, the gauge will climb as normal , then in my case slowed down and very gradually kept climbing over the next 15 minutes. Slowing down to 30 mph and the gauge brought the temp down. If instead you stop and idle at 200/210 it would boil over.


The above is what I observed in my A with rust in the radiator and block with a 2 row core.
 
I have a 6-1 Snyders head, rebuilt motor, and a new radiator, the Temp always stays at 160, except on a hot day at 95 degrees it will climb to 175-180, might go up to 185 when engine is shut off, but not for long.
 
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