overheating on 30 Model A Coupe

[dwollam]

I have a good friend who is computerless that has a very nice 30 Model A coupe that has a bad overheating problem. Radiator was "gone through" at a radiator shop, timing and fuel mixture correct, engine good shape, all the obvious things checked. Still gets really hot and blows water and steam out when warm out or pulling hills. Has tried a thermostat, has a new temp guage. 4 blade fan, belt tight, etc. Maybe radiator has buildup inside tubes not allowing good heat transfer?

Any ideas? This is a stock A also. Help! He wants to drive this car with his old car buddies and not stop every 5-10 minutes!

Thanks,

Dave Wollam

Madras Oregon

[Aanderson44]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">I have a good friend who is computerless that has a very nice 30 Model A coupe that has a bad overheating problem. Radiator was "gone through" at a radiator shop, timing and fuel mixture correct, engine good shape, all the obvious things checked. Still gets really hot and blows water and steam out when warm out or pulling hills. Has tried a thermostat, has a new temp guage. 4 blade fan, belt tight, etc. Maybe radiator has buildup inside tubes not allowing good heat transfer?

Any ideas? This is a stock A also. Help! He wants to drive this car with his old car buddies and not stop every 5-10 minutes!

Thanks,

Dave Wollam

Madras Oregon </div></div>

Model A Ford had the simplest cooling system of all, basically thermosyphon (the circulation of water through the engine block, head, into the radiator and back again, on the principle of hot water rising, cooled water falling). However, obstruction of this flow (bear in mind that a Model A water pump isn't the most efficient thing in the world, more an agitator than an actual pump) can cause overheating. Is the radiator truly clean--how did the "radiator shop" check that? About the only way to know for sure is to unsolder the top and bottom tanks, and either boil out, or "rod out" the tubes--to get rid of lime and scale in the radiator tubes. One quick check here is to feel the radiator core (from the front) with your hand with the engine running. A clean radiator will be cooler at the bottom than at the top, but the tubes should all be warm. If there are clearly cool areas, such as a set of tubes that are cooler along their length, probably they are clogged.

Also, there can be rust or scale in the waterjacket of the block, or in the cylinder head--has he cleaned those out?

Is he really running the engine properly timed, or with the proper fuel mixture? There really isn't an exact setting for either spark advance or fuel mixture on a Model A--something that is pretty hard to understand in this day and age--these are done by feel and by ear. Too many inexterienced Model A owners today think that they must retard the spark almost completely when pulling up a hill--not true--once running at street speeds, fully advanced works just fine, unless one is going up a steep hill in high gear, but the engine will tell you if it needs a bit of retarding of the spark--if too much advance, it will knock or ping--retarding the spark alleviates that. Fuel mixture likes to be set fairly lean, again once the engine is warmed up. Is there even a hint of black smoke coming out of the tailpipe? I've seen that all too often--definitely set too rich--turn down the fuel mix, as running too rich overheats the engine pretty quickly and also wastes gasoline. Too lean a mixture will also cause overheating, but generally that isn't a problem, as too lean a mixture can cause a Model A to stall out.

Has the engine been recently rebuilt? Tight bearings and piston rings cause overheating. Newly poured bearings, if they are too tight, will overheat, cause the engine to overheat as well--but they will let you know if they are too tight--the engine will start knocking as if it's got a loose rod, and when you shut it down, it will seize immediately, but will free up once the bearings have cooled. Once the bearings are worked in, the engine broken in, this goes away.

Just keep in mind, a Model A isn't a modern engine--there are no fancy diagnostics for one--it's pretty much a matter of old-fashioned observation, and things like making sure you've covered all the above items.

Art Anderson