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I wouldn't worry about the exact placement of the needle in the gauge. Lots of factors come into play for accuracy. I'm sure a 60+ year old guage is probably not 100% accurate, and they were probably not 100% when they were made. Its a relative temperature. You'll figure out where normal is, and then if it suddenly exceeds that, then you know something is happening.

For me, on the T E M P spread, mine is always around the M after warmup. It has never got past the P. Which is still not H. It has only got to the P when sitting idle for a long time on very hot day.

These guages are not exact readings. The calibration of the gauge, the resistance in any wiring and connectors, the calibration of the sending unit, and grounding quality between all the components all would affect the needle position on the gauge since it based on resistance.

An IR thermometer reading on the back of the engine and the thermostat housing, at what you believe is normal operating temp on the gauge, should give you a better idea as what that translates to as far as actual temp.

It helps to know what other people are seeing on their gauges. Thanks Kev. I guess I'm hyper aware of overheating, since that's apparently what killed my dad's '38 Super engine (didn't show up on the gauge).

My other question then would be what temperature range can the engine safely operate in? IR readings on my engine varied between 180-191 after the drive last night, depending on where I was measuring. Hottest right over the piston on #7. Is there a large range of temps that are considered acceptable?

My '05 Tundra has a huge range that is "normal". The gauge stays pinned just below halfway from temperatures 184 all the way to 221. As soon as it goes above 221 the gauge starts climbing rapidly. My assumption is that Toyota designed it this way so that people wouldn't freak out when the temperature was within the operating range.

So am I safe to assume that these old Packard engines can tolerate a range of temps without issue? Say up to 200 degrees and maybe more?

-Kevin

For what it is worth, some years ago another poster made a chart that gives some temperature to gauge correlation. He did it on a 52 model using the resistance at the sender to correspond to the gauge temp reading.

51 to 54 models have essentially the same setup with exception that some 53s had a sender issue and the mod to correct the reading might never have been done to some cars already in the field. Even with a bit of error factored in you should still be able to get some rough idea of the actual temp in your car.

As an example, if 35 ohms makes the needle rest at "T" then looking at the other chart it would indicate 35 ohms would be slightly over 150 degrees so you could probably be safe in saying the temp on your car would be in the 150-160 range when the needle is at "T".

I don't know if Packard ever gave a spec for what is an acceptable range. That would depend a lot on the climate and whether one of the optional temp thermostats was installed. Packard offered thermostats in a range of 151 to 180 degrees for the 51-4 models with 160 being the standard. I believe most would agree that the thermostat opening temp plus 10-15 degrees would be an acceptable running temp and that range would fall in line with a standard thermostat and the resistance reading for the needle being between E and M or midpoint on the gauge. Packard does mention an occasional higher reading being normal after a long slow period in traffic or after pulling a heavy load as long as that higher reading goes back down to the previous driving range within a few minutes of resumed normal driving.

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Thanks Howard, those numbers are helpful!

Another 15 mile test drive tonight, ambient temps about 80. A mix of slow and moderate speeds (25-55), some good hills, and lots of stop and go city driving. The gauge stayed mostly between E and M. After a 5-10 minute stop and engine shut down, the car ran hotter the rest of the way home. About mid to high M.

IR gauge at the thermostat housing at the above hot temp showed about 182 (remember the thermostat is a 160). Near the rear of the block by the sender showed about 191. Driver's lower corner of radiator showed 142 while the passenger lower corner (by the outlet hose) showed 165. Perhaps the radiator needs some work?

Everything else on the car did great. I have some drips on the garage floor that I need to look into. One looks like oil, and other looks like PS fluid.

-Kevin

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180-190 is not over heating, regardless of thermostat temp. Themostate rating is an opening (min) temp, not a max temp. It's there to warm up an engine, not keep it cool.

As long as your not boiling over, I think you'll be fine. Yours is running cooler that mine is if we were going off guage "temp".

That is a beautiful photo over Ellensburg! Although I lived in Washington State and bought my first four Packards there, I don’t believe I ever visited Ellensburg.

Thanks Kev. Being new to Packards and old cars in general, I am paranoid that I will make a rookie mistake and destroy my engine. I'll continue monitoring it for now to get a better feel for how the engine operates over longer drives. I'm considering driving in our town's big Labor Day parade, but not sure the car will maintain temps at such a slow speed.

Don, Ellensburg is a nice place. Smaller town but has everything you need. Lots of friendly people, and lots of nice views. No traffic!

-Kevin

Good afternoon Kevin...Driving in a parade is much like being stuck in a traffic jam...While I drive our 49 - 288 all over Scottsdale, I would not drive her in a parade...she has a new aluminum radiator and water pump and runs normally between 160 and 190 depending on the day, the traffic and such...especially if the day is over 80 degrees...just my humble opinion...Ernie in Arizona

Some more temperature data....I drove the Packard to work today. On the way home I was cruising between 60mph and 75mph for about 45 minutes on the autobahn. Temp gauge was right in the middle. At home I measured hottest about 220 at the back of the head, 185 at the front and 165 at the radiator outlet. Hot? Yes, but I dont think it is too hot. Your temps are normal.
Also the gauge will read a little high or low depending on how full the gas tank is, since those gauges share a Power source, and seem to influence each other.

Thanks for the info! That gives me a lot more confidence. The difference in temps from front to back is interesting. I'm assuming that's normal?

Was off work today so I washed the dust off the car and went on a 30 mile drive with my daughters today. Ambient temps were about 80 and the temp stayed pretty constant on the Panama. Right between the E and M except for a very long gradual hill at 50mph, when it moved to mid to upper M. Really not bad. I'm trying to burn up gallons of gas so I can fix my fuel leak at the tank and maybe drop it one last time to fix the sender issue.

Stopped by a vintage gas station/restaurant in town for a quick photo grab.

Then to NAPA to grab a couple of windshield wipers. I used NAPA 6-1233 Classic Wipers (https://www.napaonline.com/en/p/WIP61233). They are the same size as my original 11" Trico blades. I only had one blade left, and it had no rubber. These replacements aren't 100% like the originals but they look the part. I polished up the wiper shafts and installed the new wipers, looks much better than it did before.

-Kevin

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