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Here is a statement from the owner of the Packard I'm considering buying. "THE CAR HAS A NEW

RADIATOR AND THE CORRECT RADIATOR CAP. A NEW COOLING TUBE INSIDE THE ENGINE AND A NEW

WATER PUMP SO I DON'T KNOW WHY IT OVERHEATS. I RUN PURE ANTIFREEZE IN THE RADIATOR.

My thought was it overheats because he is running pure antifreeze. IT should be at least 50/50 and in the hot summer I sometimes run 100% distilled water. Thoughts?

How about defining what you mean by "overheating"? Not enough information to go by.

Boiling over?

Temperature rises under stress conditions but doesn't boil?

This info will help with a diagnosis. Also, have you checked actual temperatures with a thermometer? Have you managed to determine what position on the dash gauge corresponds to what actual temperture? What rating thermostat is in it, if any? Are you sure the therostat isn't stuck closed?

Need more info.

PS - straight water has the best heat transfer, straight ethylene glycol (which should never be used) has the worst.

Remember it's Anti-Freeze.....not Anti-Overheat.

The addition of anti-freeze to the engine coolant mixture not only reduces its freezing point, but also raises its boiling point. However, because the heat transfer of ethylene glycol is significantly less than that of water, there's a point at which higher concentrations become counter-productve.

The chemistry/physics of it are anough to give the layperson a headache, but for the sake of argument, let's consider SL Vol. 14, No. 14. Packard even recommended increasing the concentration of anti-freeze (specifically, Prestone) to raise the boiling point for unusual operating conditions - but NOT beyond 60%.

Pure antifreeze would actually contribute to overheating.

I had a '82 Toyota in my youth that I put too much antifreeze in and it overheated. Sure sounds like that is the problem here too.