WHAT ARE COMMON TEMPERATURES TO EXPECT FOR A MODEL T COOLING SYSTEM?

[Tom Donnelly]

I’m writing to see if I could please get some input from others who have experience with the Model T cooling system. Ever since I purchased my ’21 Touring in spring of 2019, I’ve kept a close eye on cooling temperatures and monitored them with an infrared thermometer. Having restored several water pump-based cars, I’m new, and trying to understand the thermo-syphon system and especially what’s normal. Early into it, I replaced the radiator with a new Berg’s (flat tube) radiator but didn’t see much change in the numbers. I recently had the engine rebuilt by a seasoned T authority and the numbers remain about the same. I use a 5W-30 engine oil, 50-50 ethylene glycol coolant, and periodically monitor/adjust tension on fan belt. No leaks, stamped brass cap with rubber gasket Ideally, I’d like to take measurements on another T or perhaps hear what others find. I greatly appreciate your feedback and here are some typical locations and temperatures I’ve been monitoring:

[dykker5502]

Do not be to focused on the numbers! As long as it does not boil intensively, it's OK.
The temperature 70 F at the return pipe indicates to me that you cooling systen works perfekt.

[TXGOAT2]

Tom: I believe those readings are in the normal range for a Model T. The Ford thermosyphon system depends on a substantial differential in coolant temperature within the system to cause the coolant to circulate. Your readings going down the radiator core and at the return pipe indicate that the cooling system is working well, with a healthy spread between the temperature at the water outlet and the return pipe. Period Ford literature indicates that temperatures near boiling at the water outlet are actually desire-able, so long as the coolant level is kept in the normal range. Using a good anti-freeze will actually raise the boiling point somewhat, which is all to the good. It should help prevent steam pockets and boilover, among a number of other benefits. A Model T with a water pump and fan probably ought to have a 180 degree thermostat to prevent over-cooling, especially in cooler weather. I'd think that carefully drilling a small hole or two, about 1/16" or so, in the thermostat's valve plate would be a good idea. Doing so would make filling the system much easier and it would assure that hot water would reach the thermostat's sensing element in a timely manner. It would also keep any bubbles that formed in the system "burped out".

[Kevin Pharis]

Your numbers show that the cooling system is clearly working with a 100+ degree temperature drop in the radiator. The funny thing about a thermo siphon system is that the coolant needs to peculate to get the system working. I ran a dash temp gage for years with no pump, and you will watch the temp rise steady to 200+, then fall like a rock. No such thing as a steady constant temp... always cycling between warm and hot

[DanTreace]

Tom

Your numbers are correct for good cooling and the normal condition of a T's thermo-syphon system, operating properly.

Here's my check of the cooling system on my '23, using a laser meter too.


https://nebula.wsimg.com/4e8f3356771456 ... 31FDB20580

[Norman Kling]

Unless your live at very high altitude, the radiator is below boiling point at 220 degrees sea level. It should run at a high temperature (below boiling) to fully vaporize the fuel and get the best efficiency. The 5 0 50 anti-freeze should keep it from boiling even if you should have a spike, such as idling at a signal after pulling a long grade. If it ran too cold you would have a lot of carbon buildup and might even need to enrich the fuel mixture. The way thermosyphon works is the principal that heat rises, so as the top of the engine warms up, the coolant will rise to the top tank of the radiator, and the cooling of the air blowing through the radiator will cool it so the coolant will settle down to the bottom of the radiator. Then as the hot coolant rises in the engine the pressure at the bottom of the engine will drop, which will cause the cool water from the bottom of the radiator to move into the engine and the cycle goes on. Many years ago when I bought my first T, it had a water pump on it when I bought it. On a cold day we took a tour up into the mountains and made a pit stop. I noticed other club members standing in front of their radiators to get warm. My radiator was cold. The water pump just causes problems and if the block and head are clean inside and the radiator is clean and also if the fins are tight fit to the cooling tubes, the thermosyphon works just fine.
Norm

[Tom Donnelly]

Gentlemen,
Thanks so much for your time and advice. I greatly appreciate it!
Have a great weekend!

[MKossor]

Here are a couple other threads with thermal images of the cooling system you may find of interest:

http://www.mtfca.com/discus/messages/59 ... 1472767249

http://www.mtfca.com/discus/messages/33 ... 1370118547