Burned Glow Plug in less than a month

[sgoodhart]

I have a 1981 240D that had two burned and bad Glow Plugs about a month ago. I replaced those and the car started fine. While I was at it I had the injectors tested and found two with bad tips although they were not the ones with the bad glow plugs. I replaced all the tips and had the injectors calibrated. The car ran fine for the last month, about 350 miles, and this morning it would not start. I checked the glow plugs tonight and found one that was no good. I pulled it and the tip was burned off. It was one of the same ones that I just replaced a month ago.

My question is what would cause the glow plug to burn in this amount of time ? Anything I can check ? I have obviously not cured the problem yet.

Scott

[sgoodhart]

Can anyone tell me if there are common reasons that cause glow plugs to burn up quickly for a particular cylinder ?

[neileg]

Is the heater current continuing to flow after the engine starts? Can't think why this would happen on only two cylinders, but, equally, can't think of another reason.

[kip Foss]

Check your glow plug timer relay. Neileg is right in that if the timer keeps the plusg on too long they will burn out for sure. I have 2 Chevy Diesel trucks that eat their share of glow plugs. Some times they just burn out at odd intervals and sometimes the timer is at fault (not often though).

You could test each plug circuit with an amp guage (I think they draw about 5 amps each), let the system cycle a couple of time and see what each plug draws. If the circuits are not the same you have a problem in the wiring between the timer and the plug I would think.

[sgoodhart]

Thank you both for your responses I will concentrate on the timer relay.

Scott