Packard Forum Index » Post-War (1946-54)

Since I replaced the head gasket, so I suppose it is possible that there could be some lack of seal, but it seems unlikely. I did do a compression test in which all cylinders were between 110 - 120. I am not sure any leak between cylinders would show in this test either, unless it was truly significant. There is no other indication of any head gasket problems, no contaminated oil or radiator water. I do get a small amount of water coming out the tail pipe on start up after a few days, which I don't remember from before on this car, but I believe it to be condensation. It seems like a leak down test might be the way to go before I pull the head, which would probably be close to the bottom of my list of things to do.

I did replace the thermostat and am finding now that all is good as long as I am moving. If I stop at a light, I can see the guage begin to climb (again, we are talking 70 degree weather). It will come back down as I get back up to speed.

I think my next step is to flush the block and to re-install my old water pump.

Just as likely, if not more so, that the radiator needs cleaning. You might want to try the old standard oxalic acid treatment on both.

I'll go with the flush before replacing the water pump.

My parts store has nothing with oxalic acid in it.

But, I do find wood bleach at my hardware store that seems like what I want. I have found a couple places on line that say to use about 16 Oz. in my system (filled with water, not coolant) run it to temp for a while, then drain and refill with clear water and about 1/4 cup of sodium carbonate (not sure where to find that yet) and run to temperature to neutralize the acid. Drain that and refill with 50/50 mix of water to coolant.

Hopefully, this will address the issue. Certainly worth a try...

The old "classic" DuPont No. 7 Heavy Duty Cooling System Cleaner was a 2-part oxalic acid and carbonate neutralizer. Both components are found at better hardware stores. Search this site and you'll find plenty of references on use.

Yes, do it with water, not ethylene glycol. And repeat if needed until the oxalic solution is no longer picking up color.

Two thoughts.

Did you install new coolant? If so did you mix it with water? 50/50. I have seen several engines run hot after a water pump change because straight coolant was used.

I changed a water pump on my 48 Chevy and encountered overheating at idle. It turned out the impeller was slipping on the shaft. Poor quaility control on the rebuilders part. I pulled the pump and pinned the impeller

Yes, new coolant added at about 50/50 - I think it might have been just a little light because I bought 2 gallons of coolant + added some left over in a container. Capacity is just under 20 Qts, so I might be just a little under 50/50, but would be quite close.

One thing I noted this morning. I parked the car a few days ago after running it to temperature. I have a 7Lb cap on the radiator. After running, the system was pressurized, but not enough to cause the overflow to leak. But the top and bottom hoses were definately hard from being pressurized. This morning, the system (at cold) was still under pressure, maybe not as much, but the hoses were still hard and I had to release the cap slowly to bleed out the pressure.

I am having a hard time figuring this out. At temperature the coolant/water solution expends and builds up pressure in the system. When it cools, it should contract back down. I am not sure why there would still be significant pressure in the system when the water certainly got down to 60 or below in the last few nights.

In the past, after cooling down, my top radiator hose would be noticeably concave at the top. I replaced both top and bottom hoses, they are clearly not contracting during operation as both get quite hard from the internal pressure. But why would they remain presurized after the water cools back down.

I am pretty certain no water is leaving the system based on the level in the radiator.

Are you sure you have a 7 lb. cap, and not higher?

IIRC the original standard radiator cap for the 1941 cars was 4#.

Running hot is often caused by several contributing factors but it would be unusual if a significant if not dominant contributor were not the radiator. Were the car mine I'd start with a good radiator cleaning followed by a gravity flow rate test.

I can see my screen name here keeps adding confusion.

I am working on my '52 250. It originally called for a 7 lb cap, but in a subsequent service bulletin, that was raised to 13 lb, if needed. I have always run a 7 lb. cap.

My next step is still to flush the radiator and the block. I was planning to do them together, but I might pull the radiator to flush it more thoroughly. That would let me do a gravity flow test before and after.

You might try adding your '52 to your signature line... it might help... a little.