summer heat

[Peyton]

In a few months, I suppose postings such as will be rare but today a 70 mile drive to/ from Jacksonville Beach in 92 degree heat made me think of this often during the drive.

Les Andrews states on Page 4-40 of his "Model A Ford, Troubleshooting and Diagnositics", that the "Model A cooling system is designed to operate at a constant temperature of about 180 degrees F at the water outlet above the cylinder head".

My concern is whether the cooling system is able to operate at a constant 180 degrees when it is 90 plus degrees outside. With or without a 160 degree thermostat, my REX-A-CO temperature guage reads between 185 and 195 degrees when it is over 85 here in Jacksonville. I've vinegared the radiator and flushed it to the point where you can drink the water coming out the petcock.

The REX-A-CO danger zone of 190 to 250 doesn't help much either---what's a guy to do!

[Purdy Swoft]

Does the manifold seem extra hot? If the points rubbing block has worn a bit, the points gap closes. As points gap closes you lose some power as it has a retarting effect on the timing. this also causes over heating.I run a gap of .022 , this may help and the points don't have to be re set as often. check timing also. When driving at speed, I run full advance, keep speed built up for the hills and never lug the engine.

[Peyton]

Thanks Purdy.

The timing and pts. seem okay and I check this on a regular basis.

Actually, the operating temps on this car have pretty much been the same for years and I wonder if I might really have no problem. It would seem that running 160 to 175 in summer heat for a Model A might be a bit of a stretch for cars running with stock radiators.

However, I really can see the effects quick changes in ambient temperature have on this car --- a downpour yesterday quickly lowered my operating temp from 190 to 160.

Peyton

[Smurkey]

I may be wrong, but I would say that if you're under 212 you're still OK as the coolant is still liquid and doing its thing.

If it was designed to run at 180, the engineers must have designed in tolerances in both directions to account for extremes in operating conditions...I'll bet it doesn't run at 180 when it's -30 below either. JMHO.

[Peyton]

Smurkey, thanks for your comments. They make sense to me but you would never know it from some posts/ threads I've read of Model A's running at 160 degrees on 90 degree days---possibly model A fish stories.

My car does not steam up on hot days and seems to run fine. Again, thanks.

Peyton

[1931 flamingo]

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If not boiling over and/or losing coolant I wouldn't worry, as who knows how accurate
your gauge is. JMO
Paul in CT

[Napa Skip]

Originally Posted by Peyton

?..my REX-A-CO temperature guage reads between 185 and 195 degrees ...

One additional aspect to consider is the accuracy of the temperature guage. The actual coolant temperature can be measured with an inexpensive "calibrated" lab thermometer with at least a 0 to 220F range. Immerse the thermometer in an ice bath, which should be at 32F, and note the indicated temperature while slowly stirring the ice-water mixture. Next immerse the thermometer in boiling water, which should be (at sea level and standard atmospheric pressure) 212F. Now you have two correction points which can be used - presuming the offset is linear - to give a somewhat accurate temperature reading by which you can judge just how accurate your coolant temperature gauge is, without resorting to more expensive alternatives such as infrared temperature indicators and the like.

But, bottom line and as others have pointed out, if you are able to drive without boiling over then you probably don't have a problem.

[Peyton]

Thank you Flamingo and Napa Skip.

[Pat Martone]

My Rexaco thermometer is very accurate as I have compared it to my digital laser heat gun, and my operating temp seems to range between 180 and 200 degrees on a hot day, while using a 180 degree thermostat. On most days, it hovers sometimes a bit below and bit above 180 degrees, depending on the weather, and if I am driving around town, or for sustained speeds in excess of 40 mph on the highway when it seems to run hotter.

I am running a heavy duty brand new 10-fins-per-inch Berg's radiator with a 50/50 mix of water and Prestone antifreeze, which a Prestone engineer told me has a boiling point of 227 degrees F.

I feel that since I have never boiled over, and I have never needed to add any coolant or any water, these operating temperatures must be OK?

Someone please correct me if I need to be worried.

Thanks.

[Peyton]

Thanks, Pat. I know the REX-A-CO gauge in my car is accurate and it seems that my driving experience pretty much mirrors yours.

[Dusty]

While on this subject is running to cold a problem? Car rarely exceeds 145.

thanks
dusty

[Tom Wesenberg]

Originally Posted by Dusty

While on this subject is running to cold a problem? Car rarely exceeds 145.

thanks
dusty

Yes, I would install a thermostat. The quicker warmup also helps.

[Pat Martone]

I recall reading somewhere that most internal combustion engines run most efficiently with coolant temperatures of 180-190 degrees.

[stouchton]

A little factoid for you all.....

The density of the air is what allows it to absorb heat. Air is actually a pitiful heat conductor.

Hence, higher humidity in the air increases its heat absorption.

So hot humid air can cool quite well. Best air right after a downpour - high humidity and cooler temps - radiators love it.


I am a thermodynamics engineer with 30 years experience, and on another board I was accused of blasphemy for these theories ........ (not Model A guys).

[Peyton]

Stouchton

Your comment about humid air being a good heat reduction for radiators and this being evident after a downpour was certainly demonstrated when I encountered a rainstorm and noticed that the temps quickly dropped from 190 to 160 degrees.

Thank you for your posting.

[Don Dahlberg]

In the summer many of us use water without antifreeze and add Water Wetter. Using water without antifreeze keeps the boiling point near 212 F and acts as sort of a safety valve or at least warning system for the engine. Water Wetter acts as a thermal conductor between the metal and the water. It can reduce the running temperature as much as 20 degrees. It also has a rust inhibitor. Of course, there is no substitute to a good radiator with clear channels.

[marc hildebrant]

Don,

That's quite a temperature drop of 20 degrees ! What do you use for data ?

Marc

[Tom Wesenberg]

Speaking of air density, that's why stationary engines and slow moving equipment cool better with the fan pushing the air through the radiator, rather than pulling it through. Pushing the air compresses it slightly and makes it denser, thus cooling better.