Glow plug testing

[vegas39]

I've discovered on two occasions now that using a test light for checking glow plugs, can be innacurate.

I tested a few on my brother in laws truck a while back and they all tested good with the light but upon hooking up power to them, only six were working.
I also discovered this on my truck the other day, I had one that showed bad with the light and I had one that tested good with the light but was no good with power applied.

The best way I discovered to test a glow plug, is to use something instead of a light that has some load to it, like a 12 volt heater or radiator fan motor. I tried this on my bad glow plug that lights up a test lamp but upon hooking up the fan motor, it would not run.

 

[Black dawg]

I like to put power right to the glow plug, I have seen way to many times, no good ones that would still pass the test light method. (even berus)

 

[Blind Driver2]

Or use an Ohm meter.

 

[kennyd]

Or use an Ohm meter.

That's the best way IMHO, one lead to ground and the other to the tip of the plug after you pull the wire off. A near zero reading (if digital) or a full scale deflection (if analog) on the meter indicates a good plug.

 

[79jasper]

The ohmmeter method is good. But I also prefer to just pull them and send 12 volts directly to the plug. That way I can see how long it takes to heat up and the heat pattern of the plug.

 

[Blind Driver2]

The ohmmeter method is good. But I also prefer to just pull them and send 12 volts directly to the plug. That way I can see how long it takes to heat up and the heat pattern of the plug.

Do you hold it with your fingers?

 

[79jasper]

Do you hold it with your fingers?

I prefer going rambo knife in mouth style. Trying to go for the joker look. But when I have to I'll use the jumper cable clamp.