Thermostat or not?

[Larry Brumfield]

Who needs an ol' thermostat anyway?

Under certain conditions the presence of a perfectly functioning thermostat, even one rated at a lower temperature, in the system of your Model A can cause overheating!! .... Notice I said "perfectly functioning." ... and "lower temperature."

If the temperature of the water in the head and engine goes higher than the rated temperature of the thermostat, the thermostat will open to try to compensate. Once the thermostat has opened as far as it will go it's allowing the maximum amount of water that can pass through it.

If the temperature continues to rise (driving fast with heavy load up a steep hill on a hot day for example) the thermostat has done all it can but its presence has now become a restriction. If the incoming water from the radiator is not cool enough to overcome the heat, the water will stay too hot. Changing to a cooler thermostat might be the remedy. Or maybe change the radiator ..... or maybe not ... it's never overheated before.

Nevertheless, at this point if the thermostat were not in the way, the hot water in the head would pass on through easier and if the cooling of the radiator is sufficient, the water in the head and engine will cool down some.

I've seen people buy Model A's with thermostats and have overheating problems at higher speeds. They try other, cooler thermostats with no luck. Then they get mad and remove the thermostat and guess what? ........ the overheating problem stops!

Now what does all this mean when trying to determine whether one needs a thermostat for their Model A?

The answer is simple.

Install the thermostat of your choice and if the engine never overheats regardless of the load or conditions and otherwise regulates the temperature correctly, then you've got it made!

Enjoy the benefits.


Larry B.

[quickchange]

Larry I put a thermostat in my delivery & it boiled under hard drive, Now before that it never got hot hence the thermostat, Id add alloy hi comp head & b carb , So next test is to take the thermostat out & test, Derek from the shakey isles today,

[skip]

So gallon [of water] flows through a hole no faster than 33 feet per minute? Want more flow? Make a bigger hole. I read that somewhere in The Pipe Fitter's and Pipe Welder's Handbook by Thomas W. Frankland.

If you look at pump discharge pipe at X gallons of flow, the pipe and valve necks up in size to allow for the slower flow of water once the water leaves the pump and slows down. Again 33 fpm.

skip.

[PC/SR]

Derek: FYI when testing the Tstat, I had a strange overheating problem when I first put in a thermostat. I put it in at the upper end of the hose to the radiator. It would heat up, boil over and the temp gauge would then go down to normal, then slowly heat up and boil over again. I checked the Tstat in a pan on teh stove and it opened OK. Taking a hint from something I read here on teh Barn I put it back in and secured it at the bottom of the hose with another hose clamp, just at the gooseneck. It has worked fine since then. This with an HC head and other stuff. My "theory" is that the engine water heated up faster than the water in the hose with limited circulation through that little hole, and the Stat opened late and then closed when cool water from the radiator had circulated, then the whole process started over again. Just a thought. As someone said, one test is worth a 1000 theories.
PS: I sometimes hear a Ham radio operator named Dave from Auckland. Dont know if he has an A. Next time I get him I will ask if he is one of your pals from the "shakey isles." Good luck. Pat

[quickchange]

Pat thanks i will investagate once back from Bonniville, Your mate Dave is on the little island Not on the mainland like me, Colder . finer, & less people on south Island, Hope no more quakes for a while, But the big one is due, Remember after just got married a big one, bed rolled across the room hit the wall & rolled back again, Just as well i was asleep, ???could have been interesting??? cheep thrill.

[PC/SR]

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Gee Derek, you had me excited there for a minute. I live about 50 miles north of San Francisco and also waiting for the Big One. Trying to figure out how to protect the A--the rest can be replaced. Have a great time at Bonneville. I wanted to make it this year but something else came up. Look for Jim Brierely and the H4H4 gang and introduce yourself. Pat

[quickchange]

Pat, Will see Jim at Vancover meet, We are judging modified. then boat cruise, Then high tail for Bonniville, Ron & some of the others are running our Quickchanges there & always a buzz watching how they do, Great gang of very kind folk.
Re quakes , we seem to be getting our share recenty, no big ones well mid 5,s . Guess when you guys pull the plug in the gulf then that oil got to come from somewhere????? Lets Go Racing.

[Jack '29 Sport Coupe]

I've had my coupe for four years and the first two years I had it I ran
with a thermostat and it ran hotter than I liked, so I took it out. It now
runs a lot cooler. Last winter, we had a couple of unusually cold months (Florida),
and I noticed that it took forever for the engine to heat up. I thought about
buying one of those after market heaters but then realized that by the time the
heater would warm up, I would be back at the house which would have rendered
the heater useless. All in all, for Florida useage, I prefer to run "barefoot." With
Florida's normally mild winter season, I will just bundle up on those rare ocassions.
IMHO

Jack

[Chris in WNC]

180 in both Model As.

they just run too darned cold without.

if yours does not, have your radiator professionally cleaned!

-Chris in HOT Florida

[Mitch//pa]

160 in all 3 A's runs perfect. all have full flow in the radiators

[Kurt in NJ]

When picking a thermostat for for an engine, or vehicle that is different from it's intended application some thought is needed, a 180 degree thermostat for a small engine will flow less at 200 degrees than a thermostat for a large truck that is rated at 180 degrees will flow at 200 degrees.

I am using a bi-metal type that has a large pivoting valve disc, when it is open it has almost as much open area as the engine necks, i chose it because it had little restriction when it was open, and it was free---I found it in a trash can (still new in the box).

For me it works---runs better, better fuel mileage(+3mpg), no overheating no matter how hot, 3mph in a parade---to 65 on the parkway.

[Preacher]

I agree with Larry... & with Kurt. I have run a Thermostat for at least 20 years. I also chose one with a large unobstructed opening. never had a problem, even after all that time. And with 4 people & all the heat & hills in French Lick. ALL items must be in good operating condition.

[steve s]

Interesting that the common thermostat allows enough coolant flow to accomodate big V8's. I guess the modern radiators are a lot more efficient, or maybe the water pumps higher pressure?

In any event, I am glad that that old hoakum about needing a thermostat to SLOW down the flow to allow plenty of time for the coolant to absorb motor heat is not in play.

Steve

[JoeWay]

Originally Posted by Kurt in NJ

...I am using a bi-metal type that has a large pivoting valve disc, when it is open it has almost as much open area as the engine necks, i chose it because it had little restriction when it was open, and it was free---I found it in a trash can (still new in the box)...

Kurt, do you still have the box? Brand and part number?

Thanks.

Joe

[Special Coupe Frank]

Right now, I'm running w/o a thermostat; just put a Bourdon-tube temp gauge on the car (bulb is in the outlet neck), and it seems to run around 155* - 165* F, even with temps in the mid 90's. It does take a long time to warm-up.

I have a new Brassworks heavy-duty 10 fin-per-inch radiator, and leakless pump.

After I get past the Scranton region AACA show this weekend, I will probably put my 160* stat back in the upper hose and see how things go.

The chief benefit of a thermostat is to get the engine up to operating temperature quickly. That said, most cars that came with water-throttling stats also have a by-pass circuit that allows water to circulate through the block while the stat is closed, preventing hot-spots during warm-up.

From the late Teen's, Hudson relized the value of keeping the engine warm, and equipped it's car with radiator shutters from the factory.

[steve s]

Originally Posted by Kurt in NJ

... I am using a bi-metal type that has a large pivoting valve disc, when it is open it has almost as much open area as the engine necks, i chose it because it had little restriction when it was open, and it was free---I found it in a trash can (still new in the box).

For me it works---runs better, better fuel mileage(+3mpg), no overheating no matter how hot, 3mph in a parade---to 65 on the parkway.

The early thermostats used bimetallics and had problems leading to their abandonment. As I recall, they locked up into one position--not sure if it was due to metal separation or fatigue or what.

Steve

[Karl]

Derek I'm running a thermostat on both mine. Prior to putting them in Motormeter would never register now runs in the "window" at high speed and below that at idle. Pretty cold driving the A's now you must be really cold on the "mainland" . I've considered putting a heater on the Sportscoupe . Do you reckon that the manifold heater would work with the advance retard mechanism set up on the RHD ?-Karl

[quickchange]

Karl. May be cooler her but not by much, But at least we get the most sun so can handle cool. No manifold heater won,t work on RHD, I have two types , one just a clip on el cheapo, the other is complete new manifold & its cover, You can fry eggs inside the car with that one. Ill look closer & see if pos to use the clipon alloy one hate to see you get the flu??Us old guys can get a jab for free, but not me. scared of needles, ???odd whiskey seems to keep flue away, cheers Derek,

[glenn in camino]

I run a 160 in my deluxe delivery. On a cold morning here in the Norcal foothills it warms up in the first couple of miles and never overheats in summer

[Kurt in NJ]

I have seen the bimetal type have a latch to hold the valve open--permanetly after overheating enough to damage the element, also I have seen a peg that is held by a low temp melting alloy to hold it open after overheating.

Joe, i do not have the box anymore, it has been installed for 25 years.

As for the bimetal failing I have seen some that have lost metal, the steel part rusted away, and cracks in 1 layer sometimes ---I see it today in fan clutches on modern cars also. I have always used antifreeze, and do not have a rust problem.