It's been in the high 80's here in Atlanta the past few days. I've been out in the roadster and noticing it getting hot, but not boiling over. I was wondering the best way to cool down a hot engine before it boils over when stopped.
Let it run slowly or shut it down? Does opening the hood work?
What makes sense to me is running it slowly (so the radiator continues to work) and open the hood.
What about while traveling? Advance the spark, enrichen the mixture, let her fly down hill in high speed?
Hot but not quite boiling is about an ideal operating temp. When planning to shut down at your destination, retard the spark, set the throttle to idle and shut it off. Expect to hear gurgling sounds as the temp equalizes and things begin to cool. All that is normal.
If the water level in the radiator is above the core but a good inch down from the neck, there may be minor overflow but that too is typical. If you fill the radiator to the neck, expect the car to spit water as it gets warm until it finds it's natural level which is typically an inch to 2 inches down from the top. As long as the core is covered with a little to spare, all is good.
If you have a brass car with no louvers in the hood side panels then opening the hood or taking it off will help.
Keep the advance lever all the way down, run at a fast idle, put some water wetter in the radiator. Full synthetic oil helps too, but it's expensive and you shouldn't need it anyway.
I had lots off over heating problems until I went to a Gates fan belt.
Another thing to consider is that the Model T thermosiphon cooling system was designed before and was never intended to be used with a 50/50 mix of modern antifreeze. For your area a maximum of 1/3 antifreeze to 2/3 water should work well and will cool better then a 50/50 mix. You could even reduce that to maybe 20/80 if your car is stored inside and protected from cold weather extremes. Some antifreeze is good for the rust protection but too much is a sure recipe for over heating problems.
I think That the let it run while cooling down theory works on cars with water pumps which will circulate the water through the radiator and block to prevent hot spots in the block if shut down.
We were all taught this long after the model T was history and all cars had water pumps.
It may or not apply to the T with a water pump depending on how well the accessory water pump works. If it works well enough in conjunction with the fan delivering enough air through the radiator to cool the water Then yes let it run.
If a hose, with water, is available running water over the radiator is a quick fix with a water pump engine. It may help with thermosyphon cooling but maybe not.
Assuming there is water in the system, if it isn't actively boiling, it really isn't overheated. No need to do anything special at shutdown time.
Walt nailed it. If it isn't violently boiling over, it's OK. It's perfectly normal to hear it gurgling after shut down. It's actually doing that the whole time you're driving. You just can't hear it until you shut down. That's the 'magic' of thermosyphon in action.
May just be over filled with water. It will spit water out if you fill above the fins in the radiator more than an inch or two. The tank should be mostly empty to allow for expansion of the warm water.
Michael, as another newbie here, one thing I've found out is if you're running a round-tube radiator, they run warmer than a flat tube. I have both. The flat tube on the '20 barely has the motometer going halfway up even on an 80 degree day. The '12 however, that's another story. Usually clear up in the middle of the "circle" near the top, sometimes almost all the way up. I richen it a bit, slow down a bit, advance a bit more (almost full anyway) and it'll drop a smidge. And boy does it gurgle when I shut it down! I put in a flat-tube in the '15 and so far what few times I've ran it after putting in the rebuilt engine, it too runs fairly warm since it's still tight, but not bad.
Michael, you might try cleaning your cooling system with vinegar and water. This was taught to me by a radiator man and it works.
Drain the old stuff out, fill the system with 50/50 water and vinegar and run the car, or drive it, for about thirty-minutes. Then drain and flush it with clean water. I had to remove the lower hose to help move the gunk out and it's bio safe and you'll smell garden fresh for at least a week.
You can use either white or apple vinegar from the grocery store and you will have to know how much coolant your system holds. Good luck and "Happy Trails."
If you haven't already done it, and even if you don't yet have a serious cooling problem, it's not a bad idea to do as Joe says and flush the system. Here's a bit of pertinent entertainment:
Your radiator will continue to work unless you have a water pump. But the air won't move through it. Perhaps parking it facing toward the wind or if you are in the garage, put a fan in front of the car blowing toward the radiator. Raise the hood so the heat can rise. The rising of the hot air will draw in some cooler air.
Letting the engine run slowly, will actually heat it up more.
With good radiator and clean cooling system when you turn off the engine, your coolant will gurgle for a second or two and then stop.
The big thing we forget about when the engine is shut down, is "surge heat." I can see this on my [gasp, choke]'49 Chebbie 1/2 ton. Watch and you can see the mechanical temp gauge rise a little after engine is shut off. With no air pulling through the radiator, the thin air around the engine can't take the heat so it rushes into the coolant, heats and expands it for a brief time.
Unless it is expanding the water out of the filler cap, your OK. Also, if your car has set for a while it maybe tight and will need a few miles put on it.