I'm just so cool.... no really!

[PeterC]

My 59A block - completely rebuilt higher horse output, new Brassworks copper radiator, 6 blade mechanical early ford truck fan, skips pumps and Robert Shewman 180 thermostats. Temp in New England was 45 today - warmed up the flatty to 160 before we set off for a run - temp went down at speed to 120! Thermostats never opened as the car could not get warm! Each head has its own new SW temp gauge plus the stock unit - all three said 120! We pulled the thermostats and tested them - opened at 180.

Perhaps too much water is running thru the pass thru holes in the high flow thermostats? We'll try soldering closed one of the three pass thru holes in each thermostat and see what happens.

So strange to have a hot (as in performance) flatty running to cool

[flatjack9]

That's what happens when you cheat to get a high flow thermostat.

[FlatheadTed]

Its best to have a radiator (as you have ) that is more efficient than what's needed ,then the thermostat keeps it up to Temperature by opening and shutting .The temperature starts /or wants to rise when sitting in a parade or at traffic lights ,the thermostat should be fully open at that point and the fan should start lowering the Temperature ,From my experience more than one hole in the thermostat will give a slow warm up .

[VeryTangled]

Hi Everyone, Some spitballing:

Maybe temporarily try some cardboard in front of the radiator to try to see if it is possible to make more heat? Maybe let it high-idle for ten minutes or so after warmed up, how hot can you get it because when you warmed to 160, you never got to the water in the radiator. It should have been cool if the stats really open at 180.

Possibly pull and test one of the new temp gauges, and verify it really works at 160-120 (confirming the other two gauges at the same time), it seems you've figured how to test the 'stats at 180, so might be easy.

What is in the cooling system? Did you use the recommended additive?

[Joe Immler]

I have never understood temperature variations in a flat head. For a time I lived in Ca. and we would tour up the mountains to escape the heat down below. After reaching the top my engine temp would be 200 to 210 degrees with 180 thermostats. On the way back down the temp would drop to around 100 degrees. I had an SW mechanical gauge. I know the thermostats worked because I would test them. Never understood this.
Now I am in Ohio. The other day the ambient temp was 40 degrees and I drove for about 40 miles. Engine temp never got above 110.
Put a half sheet of cardboard in front of the radiator to raise the engine temp like we did "back in the day" so the heater would work.

[51 MERC-CT]

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Is this a new record or has it been posted before, someone complaining about their flathead running too 'cold'.
I also had mine out today in the same weather.
I am using Robertshaw thermostats (160°) also, although in an 8BA .
Having noticed the same situation previously (would barely reach 150deg)
I installed cardboard appox. 40% covering the rad.
Now runs 160-170° as it should. No worries

[FlatheadTed]

Joe It sounds like the water is flowing around your stats ,Hose clip .Before the advent of Thermostats the common heat control was shutters ,Now in any modern car the T gauge does not move until l about 1/2 mile of driving due to the the stats staying closed .

Originally Posted by Joe Immler

I have never understood temperature variations in a flat head. For a time I lived in Ca. and we would tour up the mountains to escape the heat down below. After reaching the top my engine temp would be 200 to 210 degrees with 180 thermostats. On the way back down the temp would drop to around 100 degrees. I had an SW mechanical gauge. I know the thermostats worked because I would test them. Never understood this.
Now I am in Ohio. The other day the ambient temp was 40 degrees and I drove for about 40 miles. Engine temp never got above 110.
Put a half sheet of cardboard in front of the radiator to raise the engine temp like we did "back in the day" so the heater would work.

[Old Henry]

If you use this thermostat you will avoid the problems you are having with Shewman's stats.



It has 50% greater flow space than Shewman's and closes completely whereas Shewman's only closes 80% leaving it 20% open. It is cheaper ($10.00 compared to $25.00 for Shewman's), easier to install (goes the same place as the stock one) and is more readily avalable.

It is a Stant 14157 thermostat available at NAPA as part # THM 111, at O'Reilly as a Murray 4157, O'Reilly part number 2962, or at Amazon here: http://www.amazon.com/dp/B000C822YC.

For full discussion and test results of each stat go here:

For the Stant stat: https://www.fordbarn.com/forum/showthread.php?t=113366

For Shewman's: https://www.fordbarn.com/forum/showthread.php?t=112889

P.S. No need for carboard in front of the radiator with this stat.

[Step-down]

:Use cardboard in front of the radiator.....It's worked for the last 100 years

[flatjack9]

I've been driving mine almost daily. It's been in the low to mid 40's and with 180* stats. it runs 180. If yours is not getting up to temperature, the water is somehow bypassing the thermostats, either by design or by improper installation. No two ways about it.

[Old Henry]

One note about the stock style of thermostat installation. They tend to push up and turn then do nothing. I keep mine down with a single strand of stranded wire through the stat, down the neck, and under the hose. (Be sure to remove the rubber gasket that comes on the Stant stat as it just rolls off when the hose is pushed on and causes trouble.) Also, there is no vent hole to let air through when filling so I drilled a 1/16" hole for that. Does not affect it's function.



Others put a second hose clamp just above the stat to hold it down which is fine if you don't care about the looks.

[oldford2]

If you have a stock 46-48, cardboard is not an option because there is no access to the front of the radiator unless you remove the top deflector (5 bolts).
John

[moonshine runner]

I just recently had the radiator on my 47 rodded and cleaned out just to ensure the flathead would run temps as it should.

One day last week I drove it to work on a 32 degree morning and the air coming out of the heater was just barely warm, so I am going to get 2 new 180 degree stats and replace them this week, using Prof. Henry's method of the copper wire strands.

Such a great tip by the way!

Kevin

[L78CHEVELLE]

Just had a 1940 27,000 mile block, intake and heads professionally cleaned to remove rust and junk. Had the engine sleeves taken out and 8BA standard pistons installed. Drove the car in 70 degree weather and the car ran at 140 and would get up to 160 at idle for thirty minutes. Put in some NOS 160 thermostats and the car runs 160 all the time and goes up to 180 at idle for thirty minutes. Of the hundreds of flatheads I have owned I have never had a professional rebuilt engine that has been cleaned out. On many of the other cars I did the white vinegar deal, new radiator, modern water pumps, no thermostats, full flow thermostats, you name it I did it with various degrees of success. After a professional engine cleaning, modern pumps, and a good radiator I can understand how these cars performed when new. My over heating on the other cars was not a design problem, but a combination of many little things that had changed since the parts were new. WITH THE PROPER CARE FLAT HEAD ENGINES DO NOT OVER HEAT IN NORMAL USE!!!!!!!!!!!!!!!

[Talkwrench]

Since having my radiator re-cored with a modern CT core, Drake pumps, 180 thermostats Ive had to put a cover over the radiator so it can come up to temp in the mornings going to work..20 mins later , light traffic a few stops and starts just makes 180 at the last set of lights, weather is cool, up to 25C - [ 75F] then it comes off.

[flatjack9]

Originally Posted by L78CHEVELLE

Just had a 1940 27,000 mile block, intake and heads professionally cleaned to remove rust and junk. Had the engine sleeves taken out and 8BA standard pistons installed. Drove the car in 70 degree weather and the car ran at 140 and would get up to 160 at idle for thirty minutes. Put in some NOS 160 thermostats and the car runs 160 all the time and goes up to 180 at idle for thirty minutes. Of the hundreds of flatheads I have owned I have never had a professional rebuilt engine that has been cleaned out. On many of the other cars I did the white vinegar deal, new radiator, modern water pumps, no thermostats, full flow thermostats, you name it I did it with various degrees of success. After a professional engine cleaning, modern pumps, and a good radiator I can understand how these cars performed when new. My over heating on the other cars was not a design problem, but a combination of many little things that had changed since the parts were new. WITH THE PROPER CARE FLAT HEAD ENGINES DO NOT OVER HEAT IN NORMAL USE!!!!!!!!!!!!!!!

Well said.

[Old Henry]

Originally Posted by moonshine runner

. . . so I am going to get 2 new 180 degree stats and replace them this week, using Prof. Henry's method of the copper wire strands.

Such a great tip by the way!

Kevin

The Stant stats that I recommended are 170° stats, not 180° (Ford specified 160°) but are still plenty hot to roast one out of the car with a good heater. (I have the fresh air heater) After my car warms up I shut the heater off and still get enough heat just through the fire wall from the engine to keep at least the front seat warm.

[FlatheadTed]

Hose clips are still needed to seal of the water from going around the thermostat ,

[Terry,OH]

I had the same temperature problem without stats, so I installed Bob's thermostats. The problem was solved! About 2 months later, I have the same problem again with the stats installed, I have pulled one of the stats and it also opened at the correct temperature, as yours did. I do find the three bypass holes to be very large! I did not have the time, at that point. to investigate further, so I replaced the stat and the problem is still there. It appeared the bypass hole size may be adjustable with a shutter??? Have only pulled one of the stats on the side of my temperature gauge. I am very interested to know what you find. I contacted Bob and he is willing to replace a bad stat. I have not taken him up on his offer yet because I do not know which stat or both are bad or if a new stat will operate the same.

[Old Henry]

Originally Posted by Terry,OH

I do find the three bypass holes to be very large! . . . It appeared the bypass hole size may be adjustable with a shutter???

The three holes that look fairly large in the bottom of the cup of Bob's thermostats are not bypass holes. They are only supposed to let water go into the area of the canister that opens the thermostat.



Normally no water would pass through there at all but Bob drills three 6-7 mm holes in the bracket above that area to let water through.



They are smaller than the holes in the bottom but still let 20% of the water flow through even when the thermostat is cold and totally closed. That's the problem.