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

I think the reason they used to recommend changing to a higher temperature thermostat in the winter was to make the heater work better.

That recommendation is given in the Packard service manuals of the 30s, and for that reason. To quote from the 1937 110/129 shop manual, "These cars have cylinder head thermostats only. Thermostats marked 147 degrees are standard but units marked 162 degrees are available for temporary use with hot water heaters. The 162 degree thermostat is not suitable for use with alcohol antifreeze."

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No, it won't. You can put on a 356 water pump though. I'd go more for a fan from a later car with a/c, that would have a better chance of fitting the smaller pump hub.

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No it will not. At operating temperatures both a 160 and a 180 degree thermostat will be completely open under all but the coldest outside air temperatures. Sounds like maybe your temp gauge is defective or maybe the instrument voltage regulator is defective. The radiator is the heat exchanger and is the only thing that can remove heat from the engine. Does the radiator boil over? If not it is not overheating.

Have you ever squeezed the upper radiator hose and felt the pressure inside? If you feel pressure that means the water is above 212 degrees. It doesn't boil because the pressure cap is there. You should never remove the cap when the system is under pressure but if you did the water would instantly boil because its temp is above 212 degrees.

Try temporally installing a new mechanical temp gauge and see what that reads. My Chevy van runs as high as 240 degrees on a hot day and doesn't boil over. It has a 15 pound cap on it so the boiling point of the water is much higher.

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I completely agree with this.

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Not for very long. The engine will warm up past the 160 degree mark to the 180 degree mark somewhat slower but we are not talking about a lot of time here.

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This is what it does. You get heat out of the warm air heater faster and probably more as well.

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This is another way of saying the boiling point of the water is raised above 212 degrees allowing higher operating temperatures without loosing coolant.

If one was to install a 100 degree thermostat in an engine and the cooling system was good enough the engine would run at 100 degrees. If the cooling system was insufficient then the engine would run at whatever temp the cooling system could maintain. This is evident with changing from 180 to 160 thermostat and the engine runs cooler. Try jamming a thermostat open and running it. If your cooling system is up to snuff the engine will never warm up. This is the reasoning for me wanting to lower the temp of the thermostat. Wondering if the engine will continue to run at a higher temp and overheat or run at the temp of the new thermostat. Fuel for thought
OTG

otdgy, to try to be more helpful, I've gone back and looked again at your original statement of the problem in post #1 of this thread, and find two statements that, if clarified, might help understand the problem better:

The problem is when I drive for a while and sit in idle (i.e. traffic) the car overheats.

and,

Car does NOT overheat if I start it and let it sit. Only after driving a while

No doubt you recognize tht prolonged idle is generally more stressful on a cooling system than driving along at a reasonable road speed, and that the higher the temperature difference between the coolant and the ambient air temperature, the more effective the heat transfer (somewhat simplified). I agree with your comments about the different rated thermostats and if the car was mine, I'd change to a 160 degree, not expecting it to solve the problem but at the least it would be give me a larger margin of operating temps.

You say the car runs fine - does it loose coolant? Steam from the tailpipe when first started? Any "wet" plugs after sitting overnight? Done a compression check? I'm thinking about a possible leaking head gasket. Does the lower radiator hose seem mushy? Does it have a stiffner in it to prevent it from collapsing under the suction of the pump?

Usually solving overheating problems isn't difficult, but I've worked on and off for several years with a friends 1950 Eight (288, standard shift) which runs cool at road speed but overheats at idle. We've been thru everything and I do mean nearly everything and thus far it has defied solution. New (4-row) radiator core. We've even magnafluxed the head looking for internal cracks, pulled welch plugs looking for obstructions, and much more. Though it's a lousy solution because it just masks a problem (and is tantamount to admitting defeat!), I think we've finally come to the conclusion to put on an electric pusher fan.

It doesn't leak or steam over which surprises me. I get some white smoke briefly when I start up looks like condensation more than a head gasket. The car is in the garage which is warmer than outside. I am going to do a compression check just in case. The water level has been the same for as long as I have had the car which is why I haven't pursued this much. I checked the hoses and they are new, however I will give them a squeeze test to make sure.

The radiator guy said that the core had too many fins. Don't laugh yet.. He stated that the density of the fins is such that the radiator will block airflow. Anyone have an idea how many fins per inch they have traveling down the core ? I have been suspecting that it needs a big pusher fan to keep the airflow at idle although it puzzles me why it is fine when left in idle and only overheats after a run.
I am going to count the fins and post it. If anyone else can do the same I would love to compare numbers.
OTG

You are aware that a rise in temperature after coming to a stop after a long, hard drive is prefectly normal? You've got a large amount of heat stored in the mass of the block and coolant, and the fan and water pump at only idle speed to cope with it. After this condition, does the temperature gradually decline to "normal" with time at idle?

I suppose that "too many fins" if taken to an extreme could be issue, I'd say it's about as far-fetched as a balanced Federal budget, but let's see what fin counts folks come up with.

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I could argue this till I'm blue in the face and never convince anyone. Bottom line is the thermostat sets the bottom temp for the engine and is there to warm the engine up not cool it or maintain it at the temp of the thermostat except at very cold outside air temperatures. Seems that some people believe the thermostat does just the opposite of what it's there for. Last word.

There is a large amount of Heat Soak that happens after running a motor.

I can drive my Colorado truck, turn off the motor when it is at the 1/2 mark on the temp gauge, come back in 10 mins and start it again and for about 10 seconds it will be at the 3/4 mark until the coolant really gets circulating. This always worried me as the temp gauge in my truck has no temp markers just a L - H. So I bought a little computer unit that you can leave plugged into the ODBII port. This shows you what the computer is reading. The difference on my truck between 1/2 (~195) and 3/4 (~205) is about 10 degrees. So after I say that I stopped worrying. I leave the little computer plugged in as it show other gauges on it that my truck doesn't have on the cluster.

At highway speed you have all that airflow through radiator, and also the water pump turning at a higher rate. So that helps to offset the thermal load being produced by the motor when it is working. Suddenly come to a halt, the motor rpm drop, the waterpump slows down, the air flow through the radiator reduces (except for the fan draw). But still have that thermal load that was there from driving a few moments ago, and now it going to take longer to dissipate it. So the water temp rises until it can catch up.

This also could be a case of a too sensitive temp gauge, where a small change in temp is swinging the gauge wildly. As others have said, if it was indeed overheating, then it should be pushing fluid out at the overflow tube unless the tube was pinched off. But even then I would imagine it should start leaking out the cap itself.

Just my