Packard Forum Index » Pre-War (1899-1942)

I had the radiator on my 745 rebuilt, and everything seemed to be fine after an initial run, the thermostatically controlled louvers on the winter front opened, all seemed good.

While attempting to take a trial run before the San Marino Auto Classic two weeks ago, After a few minutes the engine overheated, the temperature gauge hit the red zone, so I shut down, cooled off and looked for leaks. Started it again after an hour, and same thing. The louvers opened, but for safety I didn't keep in running or even pull it out of the garage.

Another highly knowledgeable Packard owner at the meet mentioned a water pump adjustment, but he was not in the mood for conversation so I never got details.

There is a bit of leaking in the housing under the shaft, but just a few drops. I hope this is not requiring another radiator removal or engine teardown.

What may be causing the overheating? Any low-hanging fruit to check before I have to put this in the hands of a professional?

If you have a slight leak at the water pump shaft, tightening the packing nut slightly will probably stop it. 1/4 to 1/2 turn of the nut is usually enough, if the pump is in good condition. You don't want to over-tighten the packing. In some cases, a water pump can leak air into the cooling system when the engine is running, especially at higher speeds. That can lead to overheating. Be sure the water pump is lubricated properly, and be sure the fan belt is properly adjusted. The radiator hoses need to be in good condition and the engine needs to be in a good state of tune. Be sure the fan is not on backwards. It must pull air from front to back.