Random overheating and Fountain.

[dynaflash_8]

So i drive my 30' coupe Alot. So far, its only over heated on me twice, which is wierd. It has a 6 blade fan, fan shroud, and a 4 core rad. Ill be driving down the road and the temp will be fine, then all of the sudden the gauge will peg and the rad will shoot water out the top and drain almost the entire radiator. Let it sit, refill with water, and its fine. No overheating, no fountain, nothing. Just every once in a blue moon it does this.

Any clue?

Marty

 

[BRENT in 10-uh-C]

Marty, even with what info you have given, the details are still vague but it appears if this is a stock Model A engine that this has been an issue for awhile since you have a 6 blade fan and a fan shroud, --or someone likely would not have seen the need for those two items. What makes me wonder is if the 6 blade fan is setting up a wall of air that is trapped by the shroud which is impeding airflow through the radiator at speed.

The next question I would have is what is the condition of the radiator? I know it is a four core but those have been around for 75 years. It could be stopped up or the fins fractured from the tubes. I will say that generally speaking, for water to "shoot out" and for it to drain the radiator, that is usually caused by pressure. Steam is generally what causes this and not cylinder compression pressure. I would need to know all of the details first before what I could give an accurate diagnosis. Anything else would probably just be an off-the-wall guess at random thoughts.

 

[Glen in Hillman MI]

Dyou have a thermastat that may be sticking?.

 

[Keith True]

Actually that is something I see in old machinery from time to time.I you don't have a thermostat that is sticking you might have a piece of a mouse nest,some old acorns,nuts,twigs,or parts of a gasket floating around in there.Now and then they will fetch up in a passage and hold things back.A thermostat is much easier to plug than just the stock A tight spots.I have people say,how did anything get in there? I never left the cap off. I fixed an 8N tractor a few years ago that was full of acorns.The man had put a reman engine in it,but he did it over the winter.All the time the mice were stashing acorns in through the water inlet/outlet.I had kind of the same thing in my A pickup.It would get warm for no reason.Cool weather,hot weather,then might not do it for a month.It was acorns in the block,floating up and hitting the passages in the head.They were too big to go up into the head though.When I pulled the head I poured water in and floated some to the top.It never heated up enough to go a gusher though.It sounds kind of odd to have real pressure from time to time.If you have combustion pressure something is bad,and you will have it all the time.Not like a thermostat that will stick and let go as it pleases.