Packard Forum Index » Pre-War (1899-1942)

Hi all. Could anyone tell me what the standard 8 engine operating temp would be under normal cruising conditions. Just getting car back together and its running 165 to 180 on country backroads with inclines and decents. Cruising at an average speed of 30 to 40mph. Shutters are wired open. Engine is fresh. Any suggestions or is it right in the proper range and nothing to worry with? Thanks for replies.

That sounds like a normal range to me.

That sounds pretty good. It will probably run too cold in cool weather with the shutters wired open.

Operating temperature around 180F at the water outlet is desired.


With modern multi-grade oil and conventional "green" antifreeze, any thing up to about 190 F is OK.

Consistently running under 170 to 180F will lead to crankcase sludging and crankcase moisture accumulation in cooler weather.

It's bad practice to start any engine that you are not going to run for at least 10 miles or more in cool weather.

If you aren't going to drive the car for half an hour or more, it's best not to start it.

Packard warned against starting cars kept in storage to move them short distances, or for any other reason that involved running the engine for only a few minutes.

Packard policy was to push cars that needed moved short distances by hand rather than start the engines.

This car is gonna be a driver! I was just concerned as my 29 desoto ran around 150 and my 27 chevrolet capitol rand about 150 to 160. I didnt have a reference point orher than those cars to go by. Im sending factory temp guage out to be repaired and while its being fixed i put an autometer in to keep track of temp. Its screwed in head at factory position midmay down head.

Engines need to run warmer than that. Since alcohol is no longer used as anti-freeze, there's no reason to run an engine any cooler than about 180F, and a lot of good reasons not to.

The engine would be happiest with a water outlet temperature around 200F, but that's pushing things a little far with a non-pressurized cooling system, especially at higher alitudes or hot weather driving.

That is the reason for the thermostat. It doesn't set the "high" operating temperature for a motor, it sets the "low" operating temp. I think this is the point of greatest confusion.

I recently pulled the head of my 1929 to clean it up and replace a head gasket. Naturally I cleaned out the head, block and radiator. One thing I did do was replace the thermostat which had obviously seen its days.The replacement was made by Gates. I am running at 160F to 180F and all is happy. I am running a straight 20W50 grade oil

Where did you find the head thermostat? I dont have one and think it could be my problem.

https://www.ebay.com.au/itm/142865380972

This is the correct size