VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 engine overheating on '37???

I've got a recently rebuilt '37 216 with about 200 miles on it. It has a 160 degree thermostat, a recored three row radiator, new water pump, and the higher speed (3.73) rear end. Timing has been set to specs and the engine runs real good. It also has the smaller fan that I believe was provided with the lower speed (4.22) rear end. I took it out for a test drive today. Air temperature was about 80 degrees. Car ran fine and temp gauge indicated a temp of a little less than 180 degrees. When I stopped and let it idle for 5 minutes or so the temp gauge gradually rose to near 212 degrees. I didn't wait to see if it would boil but started down the road again and it cooled off to about 180 degrees. Is this normal? I do have the larger fan that was provided with the higher speed rear end but did not install it because I remember a post indicating more fan noise with the larger fan. Any opinions on whether the larger fan will make a difference at idle? Any other suggestions?

At idle is when you need the air flow from the fan so I would try the other fan blade. More miles on your fresh engine may help also.

It sounds like the sweet spot is at 180, but you definitely do not have enough cooling when not moving. I would try the other fan and see if temps stabilize when stopped.

It sounds normal for a newly rebuilt engine....which will run warmer. Not too much different than what my '39 would do and it has a 3.73, the small fan, block and radiator replaced so everything is clean. Give it 1000 miles and see what happens.
I have used the "3.73 fan" as an experiment and was no different except it makes more noise.

Sounds like your car is performing normally. Just drove my '40 this morning. It has a 160 thermostat and registers slightly under 180 at highway speed (outside temp 78). When idling in town it creeps over to the low end of the red 212 bar. I've been driving this car and engine since 1964 for almost 400,000 miles and it has always behaved this way. Over the years I have let mine idle for extended periods of time (30 Min) and it has never boiled over. I will admit that, when I first got the car, seeing the temp gauge hit the red bar bothered me but I got used to it. As a matter of fact, on a cross country trip from San Diego, CA to Jacksonville, FL, I threw a fan blade and since I was unable to locate a new fan, I sawed the other blade off and continued the trip and drove the car with a two bladed fan for several years before I replaced the fan. Did not have any adverse results with the temperature. The only time I ever had a overheating problem was trying to drive across the Mojave desert in the summer time. I was trying to run between 70 and 80 MPH and had to slow down to around 60 to keep the car from boiling.

I agree with the above. The 1937-1940 engines ran on the hot side. Thats why several cooling improvements were made for 1941. The shape of the grilles also had something to do with it as the wind direction also affects the temperature at higher speeds.

WOW, that is astounding! Is the engine prone to more sludging because of the high temps?

High OIL temperatures cause the oil to oxidize.....It becomes heaiver. Todays oils are very good in that respect as the oil in modern engines runs much hotter.
Modern oils can go up to 20,000 before turning into tar. I see this in lease cars the dealers buy at auctions. By 25,000 the oil is so thick it won't run out of the grain plug opening.
Change oil at reasonable intervals and there will be no problem.