Thermostat

[Mamel]

Hi guy's

I'm looking to order a thermostat for my model A,
but which one touch chose? 160 degree ore 180?

[aermotor]

I believe 160 is too cold, so I use 180.

John

[captndan]

Yes 180.

[WHN]

The Model A engine cooling system was designed to operate in the 160 to 170 degree range. The siphon design flow of this cooling system needs about 180 degrees at water pump to really get things moving. However, the other parts of the engine should be cooler.

You want to make sure your cylinder walls along with the rest of the engine stay cool. One thing you don’t want is oil flash on lower cylinder walls. Heat is your engines biggest enemy.

If your car has a correctly restored and well maintained cooling system. There should be no need for a thermostat or adding a pressure system. 90 years of service.

[Brendan]

Originally Posted by WHN

The Model A engine cooling system was designed to operate in the 160 to 170 degree range. The siphon design flow of this cooling system needs about 180 degrees at water pump to really get things moving. However, the other parts of the engine should be cooler.

You want to make sure your cylinder walls along with the rest of the engine stay cool. One thing you don’t want is oil flash on lower cylinder walls. Heat is your engines biggest enemy.

If your car has a correctly restored and well maintained cooling system. There should be no need for a thermostat or adding a pressure system. 90 years of service.

with out a thermostat, my temp gauge will not move above 100

[BILL WILLIAMSON]

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Choose according to your climate. "Seems" that most try the 160. You could change, if necessary.
Bill W.

[Curtis in MA]

Some threads on here said modern gas doesn't burn well at 100 degrees and some cars boil over using the 180 degree thermostat.

[katy]

Originally Posted by aermotor

I believe 160 is too cold, so I use 180.

John

Ditto

[WHN]

Originally Posted by Brendan

with out a thermostat, my temp gauge will not move above 100

Just for conversation. I would check the accuracy or placement of your gauge.

Every Model A engine that I have seen tested, had a running temperature test of over 160 degrees. Most were much higher.

Assuming summer day, driven a number of miles before test, head temperature.

I don’t believe the engine would run very well at 100 degrees, and there would be very little if any siphon effect for cooling. Siphon moves much more water than the water pump.

I’m not saying don’t use a thermostat. I’m just giving information on how the cooling system of a Model A Ford works.

There are many different views on everything in life.

[CarlG]

My engine builder says 180, so that's what I use.

[WHN]

Please remember if you are running a thermostat. When it is closed your water pump is trying to pump into a blocked pipe. There is no by pass for coolant to flow as with modern cars, you could get HOT spots in your engine block until thermostat opens, 180 degree thermostat will not be fully open until around 200 degrees, water pump in Model A is designed to only help at higher engine speeds, therm-siphon is main source of engine cooling. Hot spots, oil flash, things to think about.

Heat shortens engine life. You might get a little more HP, but at what cost. Enjoy.

[steve s]

There are good reasons the whole automotive world adopted thermostats as soon as reliable, "wax pellet" models became available, and why most companies struggled with less reliable options before then. Ford used bimetallic-coil models in the early 30's, but they tended to either come apart or take a heat set.

Drilling a 1/8" hole in the thermostat's flange seems to provide enough flow-by to avoid spot heating (and air bubble blockage) problems. The housing sold by Vintage Precision has a small by-pass machined into it. Some A owners have done it right and crafted a recirculation bypass tube. Others of us have a hot water heater that can serve the same function.

I saw a technical report years ago claiming that iron heads worked better at 160, and aluminum at 180. Of course, nowadays we run them much hotter.

[40 Deluxe]

Originally Posted by WHN

Please remember if you are running a thermostat. When it is closed your water pump is trying to pump into a blocked pipe. There is no by pass for coolant to flow as with modern cars, you could get HOT spots in your engine block until thermostat opens, 180 degree thermostat will not be fully open until around 200 degrees, water pump in Model A is designed to only help at higher engine speeds, therm-siphon is main source of engine cooling. Hot spots, oil flash, things to think about.

Heat shortens engine life. You might get a little more HP, but at what cost. Enjoy.

"Heat shortens engine life"?? No, EXCESSIVE heat (continual boiling over) shortens engine life, as does running too cold (below 170-180 deg.). Remember, an internal combustion engine is a heat engine! Heat from burning fuel builds the cylinder pressure that moves the pistons. The more heat, the more efficient the engine (within mechanical and thermal limits, of course). An over cooled engine does not burn fuel as efficiently, resulting in lower cylinder pressure so that more fuel is needed. More unburned fuel ends up in the oil, diluting and contaminating it, causing increased engine wear. The oil doesn't get warm enough to evaporate the contaminates out of it. More carbon builds up in the cylinders, fouling spark plugs. Fuel is not vaporized as efficiently, so the mixture has to be set richer to compensate. Heat is your friend!

[burner31]

[QUOTE=WHN;1624540]Please remember if you are running a thermostat. When it is closed your water pump is trying to pump into a blocked pipe. There is no by pass for coolant to flow as with modern cars,

One point to your comment, the thermostats used in Model A's do have minimal by-pass holes, usally two, you can see one in the photo, the other is on the opposite side.
You can, if you disire, increase the size of the by-pass holes = increasing by-pass flow.

[WHN]

Wow! Great response.

I was just explaining the designed actions of a standard Model A cooling system. If your thinking about adding a thermostat wouldn’t you want to know of any potential downfalls?

Thermo-siphon water flow in a Model A engine without a thermostat is 35 to 38 gallons per minute. Normal operating temperature is 180 degrees at upper hose (water pump), 160 degrees at lower hose (radiator outlet bottom of engine).

A modern cars water pump is moving 100 plus gallons per minute, with a pressurized, thermostat controlled, high temperature cooling system.

Water boils at 212 degrees at sea level. Denver, water boils at 200 degrees. 180 degree thermostat might not be fully open until 200 degrees? Could that be a problem in your engine? That’s up to each owner to decide.

Could some of the premature failures on newly rebuilt engines we are reading about on this forum be heat related?

Understand please. Our cars were not designed to run with a thermostat. You can add one, but understand what your doing. Any upside or downside. Enjoy.

I’m going to now have a couple of donuts!

[BILL WILLIAMSON]

Don't overthink this thing, I just got a suppliers' sleeved 160 thermostat, poked it in the upper end of the upper hose & it worked FLAWLESSLY, for 12,000 Miles, before I sold Minerva.
Bill Noworry

[steve s]

Originally Posted by WHN

...Normal operating temperature is 180 degrees at upper hose (water pump), 160 degrees at lower hose (radiator outlet bottom of engine).
...

I'm curious what your source of information is for those numbers. In my experience, "normal" operating temperature without a thermostat varies all over the place, and definitely won't get up to 160 on a cold winter day.

Steve

[WHN]

Originally Posted by steve s

I'm curious what your source of information is for those numbers. In my experience, "normal" operating temperature without a thermostat varies all over the place, and definitely won't get up to 160 on a cold winter day.

Steve

Steve, a cold winter day or a hot summer day, condition of cooling system, are all going to make temperatures vary.

I have referenced my understanding of designed calculations for this car that I have collected over the last 40 plus years.

Anyone who truly understands or cares about understanding how this very simple system works might disagree about plus or minus in the temperatures or gallons per minute. But, the system is the system. Thermo-siphon is a function of temperature differences. Remember the Model T, it didn’t have a water pump, just thermo-siphon cooling.

Both of these cars by today’s standards have a marginal cooling system at best. Anything that could add more heat might cause a problem.

I try to give my honest view on questions members ask based on what I believe to be correct. Question yes, we all should ask why. If I am wrong, give me what you believe to be the correct figures.

[steve s]

Originally Posted by WHN

... Normal operating temperature is 180 degrees at upper hose (water pump), 160 degrees at lower hose (radiator outlet bottom of engine). ...

Originally Posted by steve s

I'm curious what your source of information is for those numbers. In my experience, "normal" operating temperature without a thermostat varies all over the place, and definitely won't get up to 160 on a cold winter day.

Steve

Originally Posted by WHN

.. I try to give my honest view on questions members ask based on what I believe to be correct. Question yes, we all should ask why. If I am wrong, give me what you believe to be the correct figures.

I'm not questioning that you are giving your honest views, or your right to do so. However, giving hard numbers suggests more than just "views"--that sort of data suggests that actual measurements have been made, and that a "normal" operating temperature range has been defined and published.

All I'm saying is that in the 58 years I've been involved with Model As, I have never seen those numbers reported before, and I would like to know their source so I can evaluate their credibility for myself. I don't have alternative "correct figures" to share, because, like I said, in my experience, without a thermostat the operating temperature varies all over the place, i.e., there is no normal.

[WHN]

Steve:

Try going on line, Rocky Mountain Model A Club, Cooling System Seminar Presentation from 2012.

This is a really good complete explanation.

Realize, we all have our opinion. Comes with old age.

There are all kinds of things you can get and reference on line. Understanding that a lot of it is someone’s view. Enjoy.

Tell me what you think after reading presentation.