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

Rebuilding the engine is unlikely to affect the overheating problem. There is a cause for the overheating. Identify the cause before attempting any cures.

Packards do not overheat by any reason of flaws in design. They have a far better cooling system design than the flathead Ford V8s. If the engine overheats, there is a problem, or problems, and it's most likely that the problem or problems are in the cooling system.

Having made mistakes before based on "I checked that", though I actually hadn't checked it, or hadn't checked it correctly, it sounds to me like something you think you have checked isn't actually "correct" or "good".

It sounds like that water is getting into the radiator, because the radiator is getting hot, but that water isn't circulating in the block.

That makes me think that the inlet or the outlet to the pump is blocked. Perhaps the pump gasket is misaligned and blocking where water goes into the head. Perhaps as some have said the lower hose is collapsing or blocked. Or - since you put a new radiator in, perhaps there is something at the bottom of this new radiator that is blocking the inlet to the pump, or as some have said, the tubes are blocked.

My engine, which is a 327 essentially the same as your engine, after you start it takes about 1/2 hour or more to get up to "1/2" on the temperature gage, in typical 60 degree weather. That's with a radiator that has been "rodded out" but not recored, and has a few tubes which are clogged.

Good morning. We. had similar problems. After all the normal cleaning did not fix the problem we pulled the head and found the gasket was leaking between the center four cylinders. New gasket made things right. Ernie in Arizona.

Doug, here is an example head gasket test kit they are talking about.
https://www.amazon.com/Block-Tester-BT-500-Combustion-Leak/dp/B06VVBSFTF/ref=sr_1_13?keywords=head+gasket+test+kit&qid=1683763171&sr=8-13

If you've never had the heads off, this is worth investigating I think. This guy had a seemingly undiagnosable problem with his BMW i8, a car that cost $150,000 new. Turned out to be a bad head gasket, only way to tell was a CO2 test in the coolant.

https://www.youtube.com/watch?v=6vOsU2J5MAo

Because it's frightfully easy to do, I'd pull the t-stat and reassemble it and run it for a bit. I'm of the opinion that, if the cooling system is okay, then it wouldn't come to temp. No engine I have ever run would without a t-stat. If it doesn't get hot, then I think you could rule out the cooling system and investigate something else, like a blown head gasket.

Reading through this long thread, I did not see any mention of retarded ignition timing nor a vacuum leak. Both can contribute to an engine running hotter than normal. I think the problem trying to be addressed is on the wrong path. Hope this helps.

Note this post from someone who had similar mysterious trouble. The problem was the water pump installation

https://packardinfo.com/xoops/html/modules/newbb/viewtopic.php?topic_id=26864&post_id=257100#forumpost257100

Just had in a 53 Patty for a wakeup call. Oh did she run HOT--couldn't put your hand near the exhaust manifold to adjust the carb--and it would not idle. Found there was no gasket under the carb so it was burning a lot of very lean mixture in order to run.

I's also want to check the distributor advance mechanisms and initial timing on that car.