1934PE convertible Thermostat

I'm just completing engine block repairs probably caused by age and overheating and would appreciate some opinions on the thermostat. This is the flathead block with just the head area water cooled.

Ive taken it out and tested it and it works fine but my Mechanic suggests I leave it out permanently and warm the engine by remaining stationery for 5 minutes. His theory is this will ensure I won't get any overheating problems in the future. The car is mainly used for short journeys but might well be used for slightly longer journeys in future.

The Jury is out....opinions please

I suggest you change mechanics if (s)he is recommending leaving the thermostat out.

For '33, and I think '34, the factory thermostat was a 170°F unit. I haven’t seen those but either a 160°F or 180°F will work depending on which opinion you go with: On the 160°F you will have a bit more confidence that the thermostat is fully open by the time the coolant gets to boiling. The 180°F will keep the engine warmer and will reduce sludge build up in the crankcase and oil galleries and passages. It will also result in better heater operation if your car has the accessory heater.

For PE, you should have the bypass type thermostat which diverts water from the block back into the water pump when the engine is cold. Those are still available though the design and appearance is a bit different from the original. I believe that the NAPA part number for the 160°F version is THM 55.

Just my experience. I had running hot problems with a 33PD with no thermostat. When the thermo closes it just gives time to cool the radiator then go

through the cycle again.