Ideal thermostat temperature?

[Dave B.]

My roadster has been running very cool (as low as 130 degrees (F) down the freeway), takes a long time to warm up, and never quite gets to what I would consider to be full operating temperature.  That fact, along with comments the seller made when I bought the car, lead me to believe that if there is in fact a thermostat installed, it may be stuck open.

My question to any interested parties is whether you would install a factory (195 degrees F.) thermostat or a cooler one, say 180 degrees F.  I know it’s a trade-off between fuel mileage and wear and tear on the engine.  I have 10,000 miles on the car, which, as far as any of us know, was built with a rebuilt 1979 Ford 2.3.

-Dave

[Peter C. King]

Are you sure that the temp gauge is accurate? Is it connected to the sending unit? Is the sending unit in the engine? It’s hard to believe that an engine could run that cool. You could be up to the correct temperature. I would start with the gauge and sending unit first.

 

How hot is your heater? If it’s cooking look at the temp gauge/sending unit. If it’s not then you have an impressive cooling system. There may not even be a thermostat in there.

 

Electronics make decisions based in part on temperature. You may need 195 degrees for the system to switch off the enrichment circuit that replaced the choke.

 

 

[Dave B.]

I only noticed it down around 130F once, but that was running down the interstate at around 60-65 mph on a cool morning.  As far as whether the gauge is accurate, it does get up close to normal range at idle.  My assumption is that it should rise to a certain temperature and pretty much stay there as the thermostat does its job.

The seller commented that the thing didn’t heat well and he thought there may not have been a thermostat installed.  It does heat, but definitely not “cooking.”  And funny you should mention the choke–the engine takes a long time to come down off of high idle.  I’ll pull up to a light and it will be racing.  I do appreciate the advice and will let you know what I find when I open it up.
-Dave

[Peter C. King]

Dave,

 

OK, the gauge is working.

 

I’d bet that there isn’t a thermostat in the system.

 

Have you been tracking your gas mileage? It will go up once the correct thermostat is controlling the temp and the enrichment circuit is turned off. The heater will work better too. Just in time for Fall cruising with the top down.

 

Peter

 

[edward ericson]

Either a 180 or 195 will make a world of difference. If you have a decent fan and fan shroud on the radiator, the car should not overheat. The thermostat was definitely an excellent 1920s innovation and, imho, should not be scrapped.

[Dave B.]

I’ve only had it long enough to check the fuel mileage once, but I do have a reference point.  And by the way, have any of you replaced a thermostat on a Ford 2.3?  The lower bolt appears to be buried behind the timing belt cover.  And I think I’ll probably pull the housing off before I get a replacement thermostat so I can be sure to get the right gasket and seal.

Again, I appreciate the input.

[billnparts]

A simple straightforward project. As you don’t know if there is a stat in there or not, by all means pull the housing before you purchase one. Early motors used a standard 1.8″ diameter thermostat. if the builder went with a later housing that thermostat is much smaller at only 1.5″. Not interchangeable. Just make sure you have the correct thermostat size for the housing you have.

Bill Ascheman
Fiberfab Ford
Modified 5.0, 5sp., 4:11
Autocross & Hillclimb
"Drive Happy"

[Dave B.]

Bill,
Thanks for the advice.  I pulled off the hose today without actually unbolting the housing but I was still able to poke around the thermostat.  There’s definitely one in there and it’s definitely not stuck open.  It may just be that the thing takes a long time to warm up.  I’m going to keep a close eye on the temperature gauge as I drive it to see if there’s really anything out of the ordinary going on.
-Dave

[billnparts]

Maybe it’s a low temp stat. A 160 degree stat could be installed. The temp should be stamped on the base of the bulb if you pull it out.

Bill Ascheman
Fiberfab Ford
Modified 5.0, 5sp., 4:11
Autocross & Hillclimb
"Drive Happy"

[Dave B.]

Could be.  I haven’t driven it lately enough to get it up to temperature.  I’ll watch it closely and if I think it’s acting funky I’ll pull it out and do the old pot on the stove with a meat thermometer trick.  My wife will love that.

[Peter C. King]

If you’re going to pull the thermostat you might as well install a new one. They are a wear item and don’t last forever.

 

Running an engine too cool is not good for it. The extra gas from the enrichment circuit washes oil from the cylinder walls and contaminates the oil in the pan. Increased cylinder wear, thinner oil and lower mileage will cost you far more than the price of a new thermostat. Go with the factory recommendation for that engine. The picked that temp range for a reason.

[edward ericson]

I got it! 

Here is my theory, per Bill’s advice, above:

The P.O. has an old style thermostat housing, which wants a 1.8-inch diameter ‘stat.

The guy at the parts counter gave him the smaller. 1.5-inch ‘stat, which he installed.

The stat is loose in the housing, working effectively like a ‘stat the is stuck open.

When you get a new one, make sure it fits in there snug. You replace the old one I bet it’s the wrong size.

Bill–what do you think? Am I onto something?

[Royal]

Good thinkin Ed. That’d ‘splain it.

[Dave B.]

I see you guys will not sleep until I pull that thing out.  Expect a full report soon.
-Dave

[Dave B.]

Gentlemen,
I pulled out the thermostat and I believe Ed was on the right track.  The thermostat is a 1.5-inch thermostat and it fits nicely into the housing.  I have a few larger ones lying around and if I put one in it would sit flush with the block and the heater hose would be running from the radiator side of the thermostat, not to mention the fact that it wouldn’t fit with the gasket and would probably leak all over the place.

I believe there’s supposed to be a seal around the rim of the thermostat, and that coolant is flowing past the missing seal.  I’m going to try to track down an appropriate seal and see if that does the job.  I tested the thermostat on the stove and it starts to open right around 190 degrees Fahrenheit, which I would expect.

Thanks for the input and please let me know if this all makes sense.

-Dave

[billnparts]

Yes, if indeed you had a small stat in the larger housing that would explain your symptoms. The larger stat should cure it.
Good Luck

Bill Ascheman
Fiberfab Ford
Modified 5.0, 5sp., 4:11
Autocross & Hillclimb
"Drive Happy"

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