"wonkey" Temperature Gauge

[Ray Smith]

Started the "Big Beast" after a complete mechanical overhaul. Boy what a joy it was to finally get oil pressure to register after jumping through numerous trial and error hoops. Engine sounds fabulous, and runs greeat!!!

Problem::: My temperature gauge needle sets at 120 degrees when the engine is totally cold. When I first started the engine, the temperature gauge climbed from the 120 starting point to 212 after about 10 minutes. Stopped the engine and waited for it to cool down. Removed the thermostat and placed in a pan of water it began to open at 150 and was completely open at 160 degrees.So the thermostat is working as it should.

Is there any way that I can calibrate the temperature gauge? Is there some way that I can check to ascertain the correct temperature of the coolant?

The water pump was not changed during the rebuild of the engine. How can I insure that the pump is indeed working as it should?

Thanks,

Ray

 

[John Loftus]

Ray,

Congrats on the getting the motor running! For the temperature gauge, you could remove the temperature sensor/bulb from the motor and put it in a pan of water. Use a camp stove or equiv. to add heat. Use a known kitchen thermometer and compare readings in the pan to what you have on the instrument gauge. Sounds like you are way off ... the best fix for that is to send it off for rebuilding and calibrating but maybe others will have some DIY gauge rebuilding experience to share.

You should see water circulation with the radiator cap off and as the water starts to heat up and open the thermostat. You can also check the water in this area for true temperature. It won't be as hot as the temperature bulb area but close.

Cheers,
John

 

[Dave Russell]

Ray,
John gives very good advice. While it is possible that the engine is actually getting that hot under prolonged idle conditions, checking the gage is certainly the first step. It wouldn't be unusual for a freshly rebuilt engine to run hotter than normal for a while. Less than a few hours.

Water pumps rarely lose enough efficiency to cause problems. The seals are the part that is likely to go first.

I've found that kitchen thermometers are not always very accurate. Best to compare a couple of them. I got tired of this procedure & got an infrared "heat gun". Put the laser spot on the location to be measured, push the button, & you have instant temperature indication. Interesting to see what temperatures the various engine, cooling system, & car parts are running at.
D

 

[Ray Smith]

John, David,

Thanks for the input. I thought about taking the sensor our of the block to check, but that thing is soooo difficult to remove and replace. Any other suggestions on how I can check without removing the sensor.

Thanks,

Ray

 

[Keoke]

HI Ray, Check the temperatures by placing a thermometer in the radiator filler hole as has been mentioned.Alternatively, obtain a cheap deep socket of the correct size and cut a slot in it to fit over the copper tube .Now you can insert or remove the bulb a bit easier,Put a bit of teflon tape on the thread when you put it back in.---FWIW---Keoke

 

[spritenut]

Place the sending bulb in a pan of boiling water.
Do not let it touch the pan, just fully emmersed in water.
Pop off the bezel on the temp gauge, pop off the needle, set it to 212 while the bulb is in the boiling water.
Now it is calibrated. (within reason)
This works perfectly at sealevel, you may have to adjust your needle to your altitude. But in FL, I wouldn't worry too much about the mountains.

Frank

 

[Keoke]

Frank ,Thats pretty good never thought about doing it that way.---Keoke /ubbthreads/images/graemlins/laugh.gif