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I have a 1937 Packard 115c with a 6 cylinder engine. The radiator has been rebuilt and does not leak. My problem is that when I fill the radiator to the top I lose about a gallon of fluid driving the car 15 miles. My temp gauge starts out perfectly in the middle of the gauge reading 180 but goes a little higher with the missing fluid. The fluid is coming out of the overflow tube. I have a non-pressurized cap which is old and while it fits it seems loose after tightening. I did buy a slightly pressurized cap from NAPA but it was called a gas cap. It fit well but I remember reading that my year of car does not have a pressurized cap. But it didn't help as the water runs out of the overflow tube which is separate and not integrated into the fill opening. Is there an after market reservoir which can be added or is there another solution?

Filling to the top may be the problem. Packard recommended the coolant level to be maintained approx 1 inch below the top of the filler neck.

I don't believe the non pressure caps have the spring and seal extending beneath the cap like Packards with pressure systems do but if so, those need a long neck cap. The modern type caps usually found in parts stores are too short for Packards built before 1955 and is another frequent cause of coolant leaking out during operation.

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G'day Russell Ooms,
to PackardInfo, and I invite you to include your '37 115C in the Packard Owner's Registry.

Thank you for this. I will only add a smaller amount of water and see if it remains at that level. I'll let you know if it works!

I do think of doing this, now & again. I bought the car in Florida and had it shipped to California which is story in itself. I try to drive it a lot but the rains have kept it in the garage. It runs really well, thankfully, as I am not much of a mechanic. I had the shocks rebuilt, the entire brake system replaced, and everything to do with the front end. The glass was replaced before I bought it. I like to see, steer, and stop. I will take care of it but I do want to use it before I am used up myself. Ha!

Russell, good advice from HH56 about keeping the coolant level 1-inch below the top. The 115Cs do not have a pressurized cooling system. The radiator cap is there mainly to seal the filler neck and should fit snugly. I keep the coolant level as suggested. Never had any coolant loss or overheating even during slow moving July 4th parades. The engine temp goes to the center of the gauge when driving regardless of the ambient temp. I have a 160 deg. thermostat.

(o[]o)

One of the misunderstandings on overheating is that a low temp thermostat will help, it does not. The reason for low temp thermostats was to keep alcohol based antifreeze from evaporating/boiling off.

If a car is boiling over then it has as problem that can be fixed.