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

I have tried everything to resolve an overheading problem with my Packard. Hopefully someone can help.

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

Had the radiator checked and cleaned.. it was clean already replaced the thermostat ... that needed it. added metal tube/spacer as in stock install.
Had the water pump rebuilt (speedwell)... it was working but leaking.
Had transmission rebuilt at speedwell.
added trans cooler.. thought the trans was overheating engine.
pulled the drain plugs in the block to check for rust.. there was none. Flows fine.

Speedwell reset the carb and timing. I am assuming they are correct still.

Car does NOT overheat if I start it and let it sit. Only after driving a while. It runs great aside from the overheat issue. Shifts are firm around 35-40.

Any suggestions would be greatly appreciated.

Just out of curiosity... Is your car overheating or is your gauge just telling you so? If it isn't spouting steam or the oil pressure isn't doing funky things, it might just be a bum temp gauge sensor. It sounds like you have done all the more normal things to rectify the problem. How is the condition of your fan blades?

On my 1950 touring sedan I was concerned about accurate readings on my temperature gage and my oil pressure gage. I ran a test by hooking up Stewart Warner gages and found the Packard gages to be wildly inaccurate. I then put the SW temp gage on a bracket under the dash so I can see what is really happening when I drive.
A test is easy. Use a "mechanical" temp gage rather than an electric one because they are cheaper, they are full sweep, and there is no wiring. Just screw the SW gage fitting into the threaded hole for the heater fitting on the water pump. The water pump has water flowing in it all the time. I found a place to mount a bracket under the dash to the right of the steering column, using existing holes. It is quite comforting to be able to monitor the actual temperature as I drive.

Speedwell has an excellent reputation so I wouldn't question any of what they did. Can we assume they also checked for things like undersize exhaust pipe, restrictive muffler, fan-to-radiator spacing, correct (wide enough to not ride on the pulley bottom) fan belt, etc.

Some few of these 48-50 cars seem to defy solution to the overheating problem; I'm sure they didn't overheat when new, I'd first do as suggested and get an accurate temperature gauge and reasses the situation.

It sounds like not enough air flow through the rad. I would try blowing out the rad from behind with an air hose, or vacuuming from the front in case it has picked up a load of dust, bugs etc.

Check the fan as well. You may need to bend the blades to more of an angle or replace the fan with a newer one. Around 1952 they switched to a smaller rad and bigger fan, not sure if one will fit but if it does it should help.

One other thing. Do Packards have a water distribution tube? I know some other makes of inline flatheads do, but I don't know about Packard.

If it does check your engine for localized overheating. If the tube is rotted all the coolant will stream up the front of the engine and the back cylinders will overheat. The difference in temperature between the front and back of the engine can be quite marked.

Yes, they do have a water distribution tube.

Hi, Thanks for the quick feedback. The radiator looks brand new no dust or collection in the fins. Had a radiator guy check the internals and he said everything was fine no clogged tubes etc.. Thought about bending the fan blades but there isn't any room before it hits the generator. I put a meat thermometer into the top of the radiator and it was well over 200 degrees. The engine compartment was very hot when I lifted the hood. I wouldn't be surprised if it was 250 degrees in there. I am going to get a mechanical temp gage as suggested. Better safe than sorry. Anyone know about mounting a trans temp gage on this ultramatic ?
I purchased a ultraviolet temp sensor that I haven't tried yet. Maybe it will shed some light on the problem.

One other thing. I have the trans cooler after the radiator and someone suggested putting it before so it cools before heating the radiator. Anyone plumb it this way ?

If you have any other ideas please let me know and I'll keep you posted on what the uv says. Thanks

Though it's no doubt not a factor in your problem as it occurs at idle if I understand your question, but your stated shift point of 35-40 mph is really very high unless you've always got your "foot into it", normal shift point at light throttle opening should be 23-28 mph, give or take a few. As the torque converter is the only thing in the trans that generates significant heat, I wonder if you have the throttle pressure set right or have a governer issue. But in any case those things don't affect overheating at an idle.

I'd not consider relocating the feed to the trans cooler. It would be instructive perhaps though not necessarily diagnostic to measure trans oil temp if you can find a convenient way to do so. I've done it on my 56 by dropping a thermocouple down the filler tube. My temp measured exactly the same as the coolant temperature, about 160 F (with a 160 thermostat) after a long highway run.

It has been mentioned by O_D but check the fan belt to ensure it the proper size and is seating in the pulleys correctly. The generator pulley or water pump might be shiny if the belt is slipping. My '47 overheated after rad and waterpump were rebuilt but a new correct fitting belt solved the problem.

Was the distribution tube checked when the water pump was off? Do you see any bubbles in the coolant with the radiator cap off and the motor running?

As Dave suggested, I would check the exhaust system to make sure there is not ant type of restriction (or under sized pipes installed) that is keeping it from exhausting efficiently.

I knew a guy whose muffler was almost full of mouse charred rodent nesting/debris, and he damn near replaced everything under the hood to try to solve his overheating problem. Once he replaced the muffler, it never overheated again.