Temperature
 

Drove Ruby the ‘39 pickup this weekend. Several times actually. And it was too fun to be legal.

Here’s something I noticed. Upon start up cool engine warms to about 160 as I’m driving. Then drops and stays around 110.

Bad thermostats?

Thanks,

—Kevin

Re: Temperature
 

Sounds like no thermostats! If they are installed, they must be sticking wide open. Are you checking the temp with an IR gun or quality temp gauge?

Re: Temperature
 

Not sure the quality. But, an aftermarket gauge. The fact that it goes up to around 160 before it drops makes me suspicious of the thermostats.

Re: Temperature
 

Kevin, What you describe sounds exactly right for most any car with thermostats. What happens is, the stats are closed, isolated in the radiator hoses away from the heat source. No water is circulating, the heads get to a high temperature before the stats begin to feel the heat, after which they open, water begins to circulate, the overheated water is replaced with cooler, which levels out at normal running temperature. Your temperature gauge sees all that has happened, and scares the hell out of you. Be glad, your cooling system is working just fine.

Some stats are installed high in the top radiator hose, far away from the heat source, while others are snugged up to the heads. Both will show the symptoms described, but of course the isolated stats will show worse. Drill a couple of 1/8" holes in the stats valve to allow a constant bleed through, after which they will heat and begin opening much sooner.


EDIT: By the way, I think you mean 260ºF and 210ºF, right? :D

Re: Temperature
 

Kevin, I think like Alan; your stats are operating correctly!
mine are 160°F so they are closed until the temperature is 160°F; at this temperature they open and let the coolant circulate so the temp is lowering ; if the radiator is clean it lowers fast. on the picture you'll see the drills i made to have the coolant circulating a little.

Re: Temperature
 

Not sure why anyone would think this is normal? The thermostats open at their designed operating temperature and you may well see a temp drop when they first open, but the temp should stabilize at the designed operating temperature, not a lower temperature. That is the whole idea of a thermostat. 110 is way to low of an operating temperature. For starters I would change out the thermostats for at least 180 degree ones and 185 or 190 even better. Then when installed they should maintain that minimum temperature.

Re: Temperature
 

And don't drill holes in them!

Re: Temperature
 

Respectfully, why not?

A couple small holes let some water through while the engine is warming up to thermostat opening temp. Particularly on the 59a/b blocks the thermostat is far enough from the water in the head that with no circulation the temp sender in the head will go to 200+ before the water touching the thermostats gets up to 180. No great harm except it gets you in the habit of ignoring an overheat indication. The miniscule flow through those holes will not significantly slow how fast the engine warms up.

Re: Temperature
 

My experience has been that drilling extra holes effects the calibration. Runs colder. If you look at a thermostat closely you will see bleeding air is designed into the thermostat. Don't try to out engineer the engineers. If Stant or other manufactures thought they needed extra holes, they would have drilled them. I never saw Ford or GM install thermostats with extra holes. This is my opinion only.

Re: Temperature
 

If the stats were at the heat source as the temp sender is, then they would open as expected, with the temp sender's report following closely. I'm sure you've seen stats installed at the radiator end of the hoses, the worst place they could be, right? Without water circulation, they will remain cold until the heat finally reaches them, but meanwhile the temp sender is going wild.

The OP has aftermarket gauges, and apparently also made a typo when reporting the readings, so we don't really know where his temps actually are.

Re: Temperature
 

This makes perfect sense to me. Given that, generations of car amatuer car enthusiasts will still consider themselves smarter that the engineers who initially designed the vehicles.:rolleyes:

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The thermostat is designed to control the temp at a particular flow rate- not at any old flow rate. So what non ford thermostat for a flathead are you using. 36forfguy

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Not a typo in original post. Warms to around 160. Stays there for not long. Drops to about 110ish and stays there. All Fahrenheit.

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Yep, way too low of an operating temp, need some higher temp thermostats. Good news is great cooling system!

Re: Temperature
 

Staying at 110 degrees seems too low to be believed. Maybe the aftermarket gauge is way off. I would suggest checking with a thermometer gun. They are only about $20. Good tool to have.

Re: Temperature
 

Good suggestion Jay. Thanks.

Same thing only different, the cooling system is modified. I’m used to my ‘52 Ford tractor with a non pressurized radiator. This one has a stainless cylinder overflow of some sort on the side of the radiator. And the caps are TIGHT.