Packard Forum Index » V-8 (1955-56)

I'd sure like to get this issue corrected. The car has run hot ever since I got it. I tried radiator flush. I replaced the T-Stat. I took the radiator to a radiator shop to have it professionally cleaned. The car just runs hot, and it's kind of scary hot. The needle gets to about 1/4 - 1/8" from the "H."

Just took it for a spin a few minutes ago. It got very hot as described. Then, it cooled down a bit, to where the needle was just a 1/8" - 1/4" above the center.

That indicates to me the T-Stat must be working. Is there a chance that the T-Stat could still be a problem, or are they pretty much "they either work, or they don't?"

Jeff...temp gauge sending unit? Maybe it's time for a new one?

IDK what's considered 'Normal', but if I let my '54 idle in the summer, the gauge will move probably half way to 'H', but no further. New radiator core, religious coolant flush every 3 years, new t-stat. I know this might sound scary, but if you let her run, exactly how high does she go? Will she completely overheat, or stop at some point?

It would be interesting to hear from those in the know what the typical gauge registers as 'Normal', my sense is that it's not right in the middle as we'd like (or expect).

She overheated 2 weeks ago.

I need to start learning the parts of the cooling system. Isn't the sending unit the device that sends current to the gauge when there is heat? If so, I assume mine is working fine since I actually overheat. It doesn't just appear hot. It is hot.

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I don't believe that I yet qualify as one "in the know" but for what it's worth, my '55 Patrician runs half way between the "COLD" dot and the middle of the gauge. I do plan to check on the thermostat when I get the heater core back and have to re-open the system anyway. My '51 runs a touch past the center of the gauge. Both do this regardless of how hot/cold the outside temp is - have driven both when it's been 95 in the shade.

Packards word on the matter. Mine generally runs a bit to the hot side of the middle. Have been doing some projects so that has been in the garage and generally at a fast idle instead of on the road.

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I am definitely running hot. After idling in the driveway for 10 minutes and then going on a 10 minute drive, she is hot-hot!

The OEM temp gauge and sender are now sixty years old. Their readings may or may not be accurate.

To determine the engine temperature. the easiest way is one of the thermal guns now available. They're inexpensive; the one from Harbor Freight will do. It will shoot the actual temps of the radiator top, bottom, middle, as well as the water pump in/out.

jack vines

But I already boiled over, so I know I am too hot.

How about fluid level too high or a bad seal on the radiator cap for the coolant loss part. Recommendation is fill to 1" below neck. Have you removed the radiator cap while it warms up and monitored the upper tank inlet to verify good flow when the thermostat opens.

On another angle, any bubbles seen or perhaps you might rent equipt to test for exhaust gases in coolant.

How about some of the other occasional causes of overheating such as improper timing or restricted exhaust pipe or a stuck closed heat riser valve.