MTFCA Forum

I filled my radiator up almost to the top and have been driving it for about an hour and a half today. I was climbing some hills in low and the radiator started blowing out a lot of steam through the overflow tube. Is that a problem?

It doesnt get filled to the "top" Just to the base of the baffle. About 3" from the top of the tank. @ the top of the inlet fitting.

As stated, the radiator won't stay full to the top. Excess water will be dumped out the overflow. However, steam is another matter. The overflow should not blow steam under ordinary conditions. If you don't have a fan, climbing hills in low gear could cause the engine to boil. Using 50/50 "green" anti-freeze and water will help prevent boiling. Be sure your spark control linkage is working correctly and that you are using it correctly. Late timing under load will cause overheating.

If you fill as posted above, the top tank about half full and you are driving uphill on a hot day, it should not boil or make steam. However right after you stop and turn off the engine it might gurgle for about one minute. That is normal. If it is actually boiling and letting off steam while you are moving you could have a dirty cooling system.
Listed below are several causes.
1. Clogged passages in the radiator. Needs a good cleaning. Maybe boiled out at a radiator shop.
2. Clogged passages in the head and block. Usually this problem requires removing the head and running a snake through the passages and washing out well. Also be sure to clean out the "Steam Vents" These are small openings about 3/16" in the corners and in the center of the block and head.
3. An old radiator on which the cross fins have corroded where they are pressed into the core. This problem requires a new radiator or re-core. The old original radiators were round tube for the water passages. If you are very particular to have everything as near "original" as possible, you will want a round tube radiator. However, the flat tube radiator does a much better job of cooling, and the casual observer will not even know the difference.
Norm

As others have stated you filled it too high. Steam you will not see, but water vapor and water you can, and will, if you overfill it and it heats up. Modern cooling systems are made to run under pressure, model T cooling systems do not. So get the coolant hot, it expans, and pees out the overflow tube. Once the system barfs out the extra coolant, you should be fine from then on. Does not mean you are overheating.

If you have a healthy radiator, that was not steam blowing out the overflow tube, but hot water that, like a hot cup of coffee, produces steam when exposed to cool air. It should stop when the ideal water level has been reached for the thermo-siphon system to operate at its’ most efficient. Jim Patrick

Ok, thank you! I am going to start two other threads pertaining to cooling questions soon.

Jonah D'Avella wrote: ↑

Mon Aug 23, 2021 11:21 am

. . . and the radiator started blowing out a lot of steam through the overflow tube.

When that happens to me I tell people that it's a steam hybrid.