[Diastole]

How do you measure engine temperature?
First of all, I want to say a big thank you to all of the knowledgeable experts that have commented on this forum. There is tremendous knowledge amongst you, gentlemen, and I feel this “Thank You” is echoed by all of the other newbies on the site. Please continue to pass this knowledge down to us new to Model A’e’s as we enter our retirement years.

I purchased my first one six months ago. I have an early 1930 coupe, oval speedometer. The engine starts immediately and runs great with no knocking. There is a baffle installed in this original radiator.

I drove it for the first time last week and after about 20 minutes with some mild hills, the radiator was boiling over. I could hear steam in the engine block. The radiator was not overfilled, but the water was not as clean as it should be.

I have now cleaned the radiator and preparing for a test drive. My question is, what the best way to test for radiator function?
- I have a laser thermometer and can measure the temperature of the engine block in various locations. Is there an accepted standard of temperatures for the outside of the engine block in various locations?
- I have a digital thermometer from my wife’s kitchen where I can measure the water temperature in the top of the radiator.
- I have placed a rubber ball in the bottom of the radiator. Filled the radiator. The radiator drains to empty in 3.6 seconds which is less than the four seconds recommended by the Ford Barn.

The procedure for cleaning the radiator, y’all recommended, is what I followed pretty closely. This came from the Ford Barn experts, this thread, and others.

1. Drained all of the old water
2. Built a backflushing attachment with some new radiator hoses as recommended by Tom Endy.
3. Back flushed radiator, and engine until the water was clear and free particles. As described, I kept the pressure during engine backflush less than 15 psi.
4. Instilled a dilute soapy water solution with Dawn Dish soap. Ran the car for 30 minutes and let it soak for 24 hours.
5. Drained dirty soap solution.
6. Backflushed the engine and the radiator.
7. Instilled an oxalic acid solution in a three parts water to one part oxalic acid ratio.
8. Ran the car for 15 minutes until the engine was over 200° and the radiator fluid was greater than 170°.
9. Let the engine cool down to less than 100°. Approximately 45 minutes.
10. Drained dark green acid solution
11. Neutralized acid solution with one box of sodium bicarbonate (Arm and Hammer) in 3 gallons of water and circulated this with the engine running for five minutes
12. Let engine cool to less than 100°F
13. Back flushed radiator, and engine until clear
14. Instilled a weak green phosphoric acid solution with the same three to one ratio to give a 30% acid solution.
15. Ran engine until head temperature was 200° and radiator fluid was greater than 175°
16. Allowed the solution to sit until the engine cooled to less than 100°F. This took approximately 45 minutes.
17. Drained filthy, cloudy acid solution
18. Neutralized acid solution with one box of sodium bicarbonate (Arm and Hammer) in 3 gallons of water and circulated this with the engine running for five minutes
19. Let engine cool
20. Back flushed radiator, and engine until clear water, and free of particles.
21. Filled radiator and engine with clean water.


I do not want to give up on this radiator. But, the mentor in my Model A Club informs me that a bad radiator is a good engine killer. So, in the test drive today what do I look for? The air temperature will be 80°. There are some mild hills in my neighborhood. Idling the car will get the temperature of the radiator fluid quickly to 175° with the engine block around 200°.

Please, share some test, driving advice or any other suggestions for testing radiator function.

Thanks in advance