Topic: Flathead coolant


JHamill    -- 06-29-2021 @ 2:11 PM
  Please bear with me on this issue. Last year my '39 Ford Standard developed a leak in the coolant reservoir so I had it replaced as well as the coolant changed. This year the car is losing coolant when I park it in the garage after about a 50-mile drive. I have replaced the lost coolant with about a 1/2 quart of distilled water. I don't know the type of coolant that is in the radiator now, so should I just flush the old and start over again, or is there some additive I can use. Also, can I use a product like "water wetter" in the flathead? Their website says not recommended.

The engine runs at 170 degrees but will climb to 190 degrees on a hot day or in traffic. At what temp should I be worried about a boilover? What is the capacity of the radiator?

My wife has Alzheimer's Disease but looks forward to a ride in the country every Sunday but I am concerned the engine will overheat and I'll be stranded in the middle of nowhere with her.

Sorry for the rant but I've always gotten excellent responses from this website.





carcrazy    -- 06-29-2021 @ 8:27 PM
  The best coolant is distilled water with just a little water-pump lube or ethylene glycol to keep rust or corrosion from forming in the cooling system. If you live in a climate where the temperatures drop below the freezing point, you will have to use an antifreeze. Just follow the recommendations on the container and use as little antifreeze as possible to protect the engine from freezing. When you add coolant to the system, just fill to a level about 1 inch above the core of the radiator. If you fill to a higher level, the coolant will be forced out of the system when the engine heats up to operating temperature. I have not noticed any benefit from using water wetter.

If you are sure you have a coolant leak, you can use a bottle of Bar's Stop Leak to reduce or eliminate the amount of coolant leaking from the system.

Yours's is a non pressurized cooling system and with just distilled water as coolant the boiling point is 212 degrees F. If you use a 50/50 mixture of ethylene glycol and distilled water you can raise the boiling point.

The capacity of your cooling system is 22 quarts. As stated before, do not fill to more than about 1" over the radiator core or the excess fluid will be forced out.


JHamill    -- 06-30-2021 @ 7:02 AM
  Thank you. Your information is very helpful.


pauls39coupe    -- 06-30-2021 @ 7:50 AM
  All the advice from CarCrazy is spot on. I have used Water Wetter and noticed some decrease in temperature on my gage, just an observation, but not very scientific.
My 39 Deluxe runs modern water pumps, however I did not notice any difference, except at low speed. I also have a 4psi cap and the overflow relief valve from Skip Haney which raises the boiling point and keeps the fluid in the radiator.
Up here in the frozen north we run 50 percent antifreeze with 50 percent distilled water. Change the fluid every couple of years because the additives do wear out.
Keep the fluid just above the radiator core to allow for expansion.
Paul R


TomO    -- 07-01-2021 @ 7:54 AM
  The coolant that you see after shutting down the car is probably coming from the overflow pipe. When the coolant is heated, it expands and if there is too much coolant, it will go out the overflow.

You should let the coolant seek its normal level by driving the car for a few times without adding any coolant, just check the level inside the radiator after it cools down. If the top of the core is exposed when you check it,you should add more coolant or distilled water as you have been doing.

If you don't know the type of coolant in your radiator, a radiator repair shop can check the freezing temperature of the coolant for you. The most common coolant is ethylene glycol (Prestone) and they will use a tester that will check it. If it is a different type of antifreeze, a different tester must be used.


Tom


Dustbowl    -- 07-01-2021 @ 12:50 PM
  He asked what temperature should be be worried about. If the max he sees is 190 on hot days in traffic, I think he should not worry, especially if he has a little antifreeze in the radiator to raise the boiling point. I would be happy if my 36 - in very good condition - maxed out at 190 in traffic on hot days.

Of course, "hot day" can be 85 for some and 105 for others


JHamill    -- 07-01-2021 @ 7:19 PM
  Thank you all. Your information has been very helpful.


supereal    -- 07-04-2021 @ 10:06 AM
  I like to use the Sierra brand of coolant. It is propylene glycol, as opposed to the more common ethylene formula such as Prestone. It is non toxic to protect pets from tasting the sweet type. I mix it in equal parts of water. My water is soft, so I can bypass the distilled kind. If your engine has drain petcocks on the sides of the block, don't forget to drain those. Add a container of anti-rust before you refill the radiator.


sarahcecelia    -- 07-04-2021 @ 8:02 PM
  A 4lb. cap raises the boiling point to 224 degrees if I remember right. (3 degrees for each pound)

Regards, Steve Lee


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