Hello,

Has anyone read about a test that can be done while the glow plugs are installed to see if they are still good. I read in a manual once that you could use an ohm meter. I haven't been able to come across this again. Anyone?

What model are you working on?

Larry

I'm working on an 1987 190 Turbo Diesel.

Thanks

I tested the glow plugs on my 81 sd (found 4 were bad) with om meter by unplugging the plug that comes from the glow plug wires to the sensor unit which is on left side front fender well on the sd .With the ignition key on get a good ground with the ground probe on your tester and then probe each of the female fittings on the electrical fitting connected to the wires that leads to each glow plug , if they are good you will get a resistance reading on your meter and the bad ones will show infinity reading, the number one plug on the sd senses the time that the plugs heat before starting depending on outside temp.
William Rogers......

William gave you the correct procedure for doing a resistance test. If you have one burned open, you will find it this way.

The problem is, just because you have continuity does not mean that the plug will properly do their job. These pin type glow plugs can burn a hole in the outer shell and still show continuity.

If you're having starting problems, it's worth just replacing all of them. It will make an easier starting car almost every time.

Good luck,