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

I'm hoping one or more of you can help me with the following situation. Earlier, my 1950 Packard Standard 8 overheated. Prior to that the temp gauge normally was right in the middle of C and H. If I sat at a long traffic light in the summer it would move towards H but would go back to midpoint once I was driving again.
We solved the overheating issue...i ruled out heat riser stuck in the closed position, we flushed the radiator, checked the water pump and removed and cleaned the water distribution tube...which was surprisingly clean and unclodded. What it turned out to be was the cooling system was airlocked. After we eliminated the air pocket the car ran fine. My mechanic checked it with his infrared temperature gun after a prolonged idle and both a short and long drive...the gun consistently showed between 180 abnd 190 degrees. The only issue now, even wiht the gun showing those temps is my temp gauge is now almost at the "H" mark. I read that if the car overheats..and it did pin the gauge that one time, it can cause the gauge to not give a true rating. Any suggestions or ideas? Can the temp gauge be recalibrated or fixed? Thanks in advance!

If you can find the specs, you can pull the gauge and bench test it and the sensor with a temperature pot/calibrated thermometer and DVM/calibrator.
I don't know what std P used or who their gauge supplier was. There'e std gauge I/O conversions like 0-5VDC, 0-10 VDC, 4-20 ma, ohms, thermocouple, etc.

Check the back and see if there's a knob/screw to re-zero. If it's functional, you can bend the pointer also. These auto gauges aren't industrial quality. So may want to try to find another one.
The other option is 'eyeball correction', where it used to be vs where it is now, subtract that much visually. You're already aware it's higher, just how much to compensate.
There are people how repair vintage gauges also.
Heat gun on the outside will read hotter than the thermostat setting, metal is radiating. I think these are 160F open stats. The water will be hotter.
Air controlled, so not unusual to see a small rise idling but should not overheat. My 288 could idle in the drive for long periods without heating. They idle low and there's not much heat and the straight design dissipates it well.

Thank you. I appreciate the information!

In the 48-50 22,23 series cars the gauges are different from all other years.

Any year other than 48-50, the sender is a straight resistance unit where a changing fuel, oil, or temperature parameter will change the resistance and vary the current to the gauge so heat generated by a heater element wrapped around a bimetal strip on a thermal type gauge or in other years, vary the strength of an electromagnet coil on magnetic type gauges. That change in current will make the needle move proportionally. While the resistance range of the senders did vary by year and gauge type or brand, modern senders can be found that will work on some years or on senders with completely obsolete ohm ranges, repros can be made by KM Lifestyle.https://mykmlifestyle.com/

In the completely different 48-50 gauges there are two bimetal strips -- one in the gauge and one in the sender -- operated by heaters wired in series with each operating their respective bimetal strips. The senders in those years do not provide a varying current but rather a straight on/off contact action of solid ground or an open contact. A closed contact will provide the 6v going to the gauge a solid ground and a lot of heat can be generated by the heater around the gauge bimetal. The frequency and duration of the on/off pulses is determined by how much physical pressure is being applied to the bimetal strip in the sender. That is determined by a diaphragm which is in direct contact with the respective fluid being measured. A weak pressure and the action is quick and frequent and gauge heater doesn't get much time to heat so needle stays near the off or resting end of the gauge, higher pressure and the on time delivering a straight ground to the gauge is longer and will make the heater move the bimetal strip and needle more so it displays the reading at the end opposite the resting end. The off or open contact period between the pulses allows the gauge heater to cool slightly so the needle stays fairly steady. If it did not have the cool off period the needle would continue to climb each time the ground was applied. The heaters in each component being connected in series along with the sender contact action affecting the sender heater at a different time makes them respond in complementary ways so a kind of feedback is generated and keeps things in sync.

It appears original NOS Packard senders for the 48-50 models are all but extinct and expensive if you find them. Ford and some other brands also used a similar type system and maybe something could be found from one of their vendors that will work and that may be what some of our vendors have done.

I do not know if KM Lifestyles can remanufacture that type sender but I kind of doubt it since there are many trying to find affordable working senders or make a straight resistance type work. As far as I know, while there have been attempts to find a modern resistance type sender that will work the the 48-50 gauges, no one has been completely successful.

thank you, Howard. this really was helpful. Ray

From HH's explanation, it sounds like the strip might have been over-extended (too much heat) and lost it's shape. If one can find the correct parts, could be repaired by a gauge person, but not your typical DIY job.
There's a few 22-23 parts cars out there so maybe a "find it". I might be willing to let mine go, if non-existent, as it's destined for non-stock but was keeping all the stock items.
Since it works but only reads off, I'd let it go as a badge of experience for that car.

Ray,
Keep in mind that your Packard came new with a 145-150 degree thermostat and a 155-160 deg. (high reading) as an option.
A water temp of 180-190 would read high on the gauge.
John

john. i think you just solved the mystery. i think I put a 180 degree thermostat in her, thank you!

that is incredibly generous of you! I just read that i may have put the wrong thermostat in the car. let me put the correct one in and see if that solves the issue. I would not want to take your part unless it was really necessary. thank you for your help!