To Stat or Not To Stat? That is the question.

[Old Henry]

To try to answer this question I devised a controlled scientific experiment taking two drives over the same course attempting to duplicate everything about each drive except one was without thermostats and the other was with Stant 14157 thermostats installed. (More about them here: https://www.fordbarn.com/forum/showthread.php?t=113366)

4.8 miles from my house is the beginning of Squaw Peak Road that rises 1,779 feet in 4.1 miles (8% grade) to Squaw Peak Overlook. (Put that in Google Earth to see it.) It is the only road in Utah that I've ever overheated on, although it was only once. Last Saturday, the 3rd, I drove from my house to Squaw Peak Road then up the road to the overlook recording elevation and temperatures every mile along the way going up and coming back. I could only go 20-25 mph in second gear going up the climb. When I got back I intended to install two Stant thermostats and do it all again that day but when I opened one of the boxes it had some other thermostat in it. So, I had to take that one back to O'Reilly and order another that didn't come in until last night. So, had to take the second ride with the thermostats in today. Everything about the drive was identical to the one Saturday except the outside temperature. On Saturday it was 90° and today it was 84°. I don't know how much difference that 6° makes to my conclusions. I let you decide for yourself.

The data for the two drives is in the attached PDF file if you want to open it and study it. Here is the data in graphic form (done by VeryTangled subsequent to initial report):



Before reporting what I learned new let me review facts that I think are not largely disputed.

1. Engines run better, more efficiently, and last longer if they are kept above a minimum operating temperature. The moisture and other contaminants in the crankcase evaporate instead of condensing, mixing with the oil, and contaminating it. For my 59A in my 47 Ford specifies a 160° thermostat which would seem to indicate that is the minimum recommended operating temperature.

2. On the other hand, if an engine gets too hot the water boils out and if it's not cooled quickly it can be damaged by the heat.

3. Thermostats are ideal for getting an engine warmed up to operating temperature quickly and keeping it from dropping below that. However, the thermostats currently being sold to replace the Ford butterfly valve thermostats are much lower volume and, in some instances, including if there are any other problems with the cooling system, they may restrict coolant flow enough to cause or contribute toward overheating. See more discussion about that here: https://www.fordbarn.com/forum/showthread.php?t=112889

So, with greater concern about overheating than underheating, many remove the thermostats and run the engine without them. I have done that, not being sure whether it made any difference or not. But, for me, I can't do that all year round cause it gets real cold where I live in the winter and I've got to get the engine warmed up to get heat out of the heater. Plus, after a long descent down a mountain my engine gets too cold and starts running rough.

So, although I had no doubt that there were benefits to thermostats at lower temperatures, I needed to know if they really did cause or contribute to overheating. That's why I did this procedure. To find out.

Here's what I learned.

1. It was no surprise that the engine warmed up to proper operating temperature much faster with the thermostats in than with them out, in fact twice as fast - 3 minutes with stats compared to 6 minutes without.

2. I was a little surprised that coming down the 8% grade for 4.1 miles that the thermostats actually kept the engine at operating temperature and prevented it from getting down to 130° that it did without them.

3. The best news of all was that the maximum temperature that the engine reached at the top of the climb was within 1-2 degrees whether or not I had thermostats installed. I must add that such was with the Stant thermostats that have 25% greater flow than the ones generally being sold for the 59A engines. I don't know whether the results would be the same for them and don't need to know since I will only be using the Stant stats from now on.

So, in my humble but studied opinion, there is no reason to run a flathead without thermostats if you use the Stant stats.*

Here's a picture I took up at Squaw Peak Overlook when I got up there looking down to where I live.



* The one exception would be if you use Skip's pumps that are not recommended for use with thermostats. They are designed to move more volume provided there are no restrictions - kind of like a fan vs. a compressor. For full discussion of difference go here: https://www.fordbarn.com/forum/showthread.php?t=106054