Cat 12F grader glow plugs

[Onfoot]

As I continue to learn the ropes, I am wanting to test the glow plugs on my 1968 12F. (S/N 58H498) The current p/n is DS-3T-9562 (original p/n 3S-9624). Can anyone tell me what should be the ohms? Thanks!

 

[Coaldust]

You will see .5 to 1.5 ohms. Really, what you are looking for is an open circuit (OL) and anomalies. Good or bad.

 

[Coaldust]

Those are heavy duty, power consuming glow plugs. They can ohm-out OK and still not work right. Especially if you are using a modern digital high-impedance multimeter.

I recommend individually jumping them with a 24volt + test wire and looking for a spark at the terminal. Easy-peazy.

 

[Bluox]

Take a 24 volt test lite and hook the ground clamp on the battery + post .
Unplug the glow plugs and touch each one with the test lite, if it lites plug likely good if it don't lite plug bad.
Bob

 

[Coaldust]

Thats a good technique.
Safer than my method. (I do use a fused jumper wire)

 

[Onfoot]

Thanks for the help! Useful advice. Think using a 24v test light makes sense. You guys are great!

 

[John C.]

An ohm meter works just fine. Just pull the connecting wire off before testing a plug. The failure mode is a short to ground or no continuity at all. Those plugs use about 7 amps each. If you have a working amp meter on the panel, it should go all the way to the left when you turn the switch to heat. That should be no less than 35 amps.

 

[Onfoot]

An ohm meter works just fine. Just pull the connecting wire off before testing a plug. The failure mode is a short to ground or no continuity at all. Those plugs use about 7 amps each. If you have a working amp meter on the panel, it should go all the way to the left when you turn the switch to heat. That should be no less than 35 amps.

Thanks, John C. Useful info. Amp meter goes about halfway to the left at present. I'm guessing that there are at least a couple of glow plugs that are toast.