Testing temp sensor on non-running engine?

[barmanvarn]

Getting really close to firing this sucker up. Just waiting on a carb rebuild kit to arrive.

A while back I found the wire to the temp sensor had some bad spots in it so I cut out the bad wiring and spliced in new wire. Also cleaned off the sensor and whatever it is that it attaches to on the engine.

Got me thinking....once I get the engine started I want to make sure it doesn't overheat on me.

Is there a way to test the sensor and gauge in advance so that I can confirm they are working before I start the engine?

I know that once the engine starts I can just watch the gauge to see if it moves after a bit, but was just curious if it's possible to test in advance.

thanks

[hamjet]

I would think if you ran a piece of wire from frame to outside threads on senser (with senser hooked up) and stuck the senser in a cup of hot (boiling) water you should get a reading. At least it would tell you if its working...

[barmanvarn]

Took me a minute to picture what you were talking about. LOL

I guess the wire is to ground the actual temperature switch (or whatever it's called)?

So remove the switch from the engine, use the wire to ground the switch, attach sensor to switch, and then dunk it in hot water. That sum it up?

[hamjet]

Yes, the senser would have to be out of the engine,( I didn't know you already had it in the engine). I know you can test the wireing to the gauge by using an ohm meter but I don't have the info in front of me. Did you already fill the system with antifreeze?

[barmanvarn]

Originally Posted by hamjet

Yes, the senser would have to be out of the engine,( I didn't know you already had it in the engine). I know you can test the wireing to the gauge by using an ohm meter but I don't have the info in front of me. Did you already fill the system with antifreeze?

Yeah, all fluids are good.

I looked up pricing and a new sensor is only about $12 bucks so I may go ahead and pop a new one on just to be safe. And as you suggested, I can check continuity from the sensor to the gauge. That may be the safe way to go.

The last thing I want is to finally get the engine running, just to have it overheat and melt down on me. LOL

[mechanicalman]

Originally Posted by barmanvarn

Yeah, all fluids are good.

I looked up pricing and a new sensor is only about $12 bucks so I may go ahead and pop a new one on just to be safe. And as you suggested, I can check continuity from the sensor to the gauge. That may be the safe way to go.

The last thing I want is to finally get the engine running, just to have it overheat and melt down on me. LOL

As long as you popped the heater hose off the intake and filled the coolant so that it gets under the new thermostat that you installed and checked for sticking, you will be ok you can just test it when you start the engine.

[MARKDTN]

There are charts in some of the older manuals that give temperature vs: resistance measurements for that sensor. You would immerse the tip of the sensor in ice water and it should read XX ohms. Then immerse it in boiling water and it should read YY ohms. Like that. Look in the Factory Shop Manual.

[barmanvarn]

Thanks for the info folks. Fingers crossed that the carb rebuild kit arrives by this weekend so I can take another shot at getting it running.

Went and picked up new rad hoses, coolant temp sensor, and thermostat. If I can get it running, I'm going to immediately turn it off and flush/fill the rad.

I know I should prob flush the rad first, but have decided to wait until I'm sure the engine is going to run.

Side question, any tips on flushing the coolant system on these things?