The Stovebolt Site Forums The Shop Area Engine Shop operating temperature

Hello folks,

I've just bought a 1941 Chev half ton with the original 216 and four speed box. I've had it out a couple of times enjoying the experience of using the crash box!! I drove the truck about 12 miles yesterday, a few hills so I could practice going up and down the gears. The temp guage sat on the 0 of the 180 mark and I was wondering if this was normal or a little on the high side. Thanks

Sounds a little high. First thing to do is check your water temp. With the engine warm and water flowing through the radiator (thermostat open) put a thermometer in the water. I use a meat thermometer that I know is fairly accurate. It should be the same as the gauge. If it's not the same, you will know how far the gauge is off.

If it is the same, pull the thermostat and check the opening temp on it.

With a clean radiator, the top tank temperature should be close to the same as the thermostat setting. The early radiators can't stand much pressure on the core, so getting way above boiling like a modern radiator and allowing the pressure to keep the coolant liquid isn't an option. The boiling point rises 3 degrees for every pound of pressure, so a high-pressure radiator can get up to 250 degrees or so with enough cap pressure. The old stovebolt systems shouldn't get above 200, even on a hard pull. 160 to 180 is better!
Jerry

Fred and Jerry, thanks guys. I'll check the water temp tonight. I had a look under the bonnet and noticed that the PO has installed a 13lb cap. I'll try and get a 0lb or 4lb cap and see what difference this makes.

my 46 had an original non-pressure cap - don't think they used pressure caps those years

Bill

Cheers Bill,

It is a non pressure sytem as far as I'm aware as well. I can get a 4lb rated cap no problem but no luck yet with a 0lb one. I'll try it with the 4lb one to start with and see if there is any improvement.

All the best
Bob

The 4# cap should be OK. Combined with a 160 degree F. thermostat, it would be unlikely to get hot enough to pressurize. Just be sure the radiator is clean, and the water pump is working properly.
Jerry

Thanks Jerry. I'll try the 4lb cap and take the truck for a run. Everthing has been rebuilt on this truck. I don't know what thermostat is in at the moment but this weekend I'll drain and flush the system and pull the thermostat to see what one is in. I checked the water temp and the gauge is working ok. Its coming into summer in this part of the world so its a good time to get this sorted. Thanks again for the help mate.

Bob

Sounds like it's time for some radiator work. You can take it to get cleaned, but most of them that are this old fall apart in the tank when they are boiled. Talk to a radiator shop about your options.

UPDATE

I changed the 13lb cap for a 4lb, made no difference to the temp. I pulled the thermostat and it was pretty bad. I couldn't make out which range it was in. I flushed out the radiator, took out the block drain and reverse flushed the motor until I got clear water out of the block drain. I did this three or four times and rodded the block drain between flushes with a length of wire cut from an old coat hanger. I didn't get much gunk out though.I put in a 160 thermostat that I checked was working ok and had drilled a 3/32 hole in the collar. I have still to add coolant as I wanted to take it for a run with just water in it to check if things were ok. Anyway I took it for a 20 mile run and it didn't go above 180 on a long steep incline. It sat on about 160 - 170 the rest of the time. I'll keep a close eye on it though. Thanks for all the help guys.

Bob