The Stovebolt Site Forums The Shop Area Engine Shop heat gauge

I have a rebuilt 261 engine, rebuilt radiator and rebuilt gauges. Basically new or rebuilt. While driving my truck, I am watching my heat gauge. No way to determine the temperature but the gauge reads high. I am concerned about the engine temperature. Where should the gauge ride?
thanks, larry

where ever, they're all different, especially 50-60 years later - what you need to do is get a laser infrared thermometer and check at the thermostat housing as well as top and bottom of the rad and see what the actual temp is, then you'll know what the gauge is telling you, compare a few times - the main thing the old gauges are useful for is indicating if there's a problem by showing a change from usual

Bill

What degree of thermostat are you running and what temp does the gauge say ?


Tim

In response to red58:
I did not know there was a laser infared thermometer tool. Looks like a good idea. I will then know weather I have a problem. Good advise.
In response to bowtietim:
Not sure what degree thermostat. The gauge on the truck does not show the temperature. The gauge shows cold on the left side and hot on the right side. Seems to run 3/4 up from cold to hot on the gauge.
Larry

I would think you need to know what degree of thermostat your running first.

Here is a link to the thermostat in the 1954 shop manual. thermostat

Maybe Tim Lederman will chime in soon.


Tim

Tim - checking the actual temp can tell you what thermostat you're running, just start checking the top rad hose cold until the temp jumps up .... if the temp is too low or high then you'll want to open it up and check the stat, otherwise why bother? checking the temps at various places is worth doing as a routine maint step, make sure the system is operating properly .... the one thing these trucks lack is a good temp gauge, they should always be checked against what's really happening to know what they're trying to say, originally mid range was usual, but they're all different

Bill

I bought a laser thermometer. Took the truck out for a run. The gauge on the dash reads 3/4. The laser thermometer reads 225 at thermostat housing. Top of the radiator reads 220 and the bottom of the radiator reads 168. The thermostat is probably 220. Looking for some input.
Larry

I believe you should be running a 180 temp thermostat.


Tim

I doubt you have a 220 stat, but time to check it in a pan of water on the stove to see for sure when it opens, or just replace it [but check the new one before installing!!] - as Tim sez, 180 is the highest rating you want .... but your rad sure is working well

Bill

I checked my temp gauge on the stove also. I compared the reading to a digital thermometer. Amazingly, it reads accurately.

4 psi radiator caps and around 150-160 degree thermostats were standard in 1954 trucks. Higher temp thermostats were used on larger trucks (180-190 degrees).

As Tim asked, what degree thermostat and what pressure radiator cap are you using?

I talked with Patrick in Arizona. I sent him a picture of the water pump. Patrick said I needed a 7 inch pulley on the pump. My pump has a 4 inch pulley. I pulled the pump and replaced it with one with a 7 inch pulley. Also lowered the radiator 1 inch". I removed the thermostat. Checked on the stove and it appears to open at 195 degrees. Tomorrow I'm heading for the auto parts store and buy a 180 degree thermostat. Also going to buy a radiator overflow tank.

What year 261?

What year and size truck is it in?

How did you lower the radiator 1"?

When you had the engine rebuilt, what was done to clean out the water passages in the block?

Did you measure the temperature at the front and rear of the block with the infra-red thermometer?

The water pump pulley size should have a big impact on temperature. Keep your fingers crossed.

The engine is a 1962 261 in a 1955 1st series 3100. lowered the radiator 1 inch by drilling new holes in radiator flanges. Measurements were taken on both ends of the head. Should have it all back together in a couple days.
larry

All back together and decided time to take the truck for a run. Drove out towards the locals hills. Great early evening run in the truck. The temperature gauge in the mid zone. Lazer thermometer shows good temperatures all around.
When I got home there was water leaking under the truck. The water was coming from the overflow line on the radiator. No other leaks. I plan to buy and install an overflow tank.
larry

Larry,

It's normal to loose some water after a refill, the water expands and burps out when you turn the engine off. Run it again without toping it off and you should be fine.

I'm not sure an overflow tank will work with the old style radiators, there's no way to suck the coolant back in after it burps out.

Mike B

what Mike said Larry, these old systems were designed to be "filled" to a level below the neck when at operating temperature, filled cold it should be at least 2-3" below the neck

Bill

I'll not top off the radiator and take it for another run tomorrow. It was a good feeling to resolve the over heating issue.
larry

Some of the Shop Manuals explain the normal expansion of cooling fluid and the waste of coolant that WILL ALWAYS occur if the radiator is filled to the top.

Nonetheless, a radiator overflow tank was available during many Stovebolt engine years. This tank is unlike modern over-flow tanks, and it was purposefully mounted higher that the engine/cooling system (to allow flow back via gravity).

Here is another discussion of the overflow rank.

I simply under fill the radiator and/or let the radiator overflow until it reaches the appropriate level.

We have had triple digit temperature here in Boise Idaho. The temperature on the truck is holding well. Looks like the temperature issue is resolved. I want to install an overflow tank. I bought the tank today. The tank is a stainless cylinder two inches diameter x fifteen inches long. Next on the agenda is to install the overflow tank. Plan to attach the tank to the radiator attach flange on the passenger side.
Larry

Where did you get the lazer thermometer? Harbor Freight or something similar?? My temp guage currently doesn't register anything. I'd like to do some of the trouble shooting mentioned above.

Thanks

It is actually an infrared thermometer.

http://www.harborfreight.com/catalogsearch/result?q=Infrared+Laser+thermometer

They come in handy
...click...

use it around the house too

I guess the pointer on the gun would be described by some as a lazer. Maybe it is just a red colored light. They are a great tool.

nix - the red light on a non-contact thermometer is a laser, intended for 'targeting' - most are rated to 'average' the temperature over a certain area which is the spread of the light at a certain distance [like 1 sq inch at 12"] .... interesting use, point the tool at the clear sky and see the approximate temperature of the upper atmosphere

Bill