1981 Mercedes Benz 300d



March, 9, 2011 AT 5:37 PM

Hello! My vehicle is a 1981 mercedes 300D. I have just replaced my glow plugs. I worry about the relay failing, my glow plugs staying on and having a shorter lifespan. I am considering opening the hood each start, and inserting the fuse [the breaker located directly over the LF wheel], starting the car normally, removing the fuse, closing the hood, and storing the fuse in my glove box until the next start. This sounds like a nuisance to me. Is there a less cumbersome way I can be assured my glow plugs will be on ONLY when I want them on, and thereby have longer lifespan?


2 Answers



March, 9, 2011 AT 5:47 PM

Suspect control unit temp resistor faulty see diagram. If operating will not allow plugs to have power over 25 sec.



November, 3, 2012 AT 12:12 PM

Most impressive answer by Docfixit, Here's another question, please.

I have a 1975 Mercedes 300D which has ignition and/or glowplug and/or relay issues. I assume (always dangerous) that this relay is a box of primitive electronics?

The only parts which I can see listed are M-B units at $350 or thereabouts. Is there a reputable supplier at more realistic pricing?

I guess that I should also ask whether one can test this relay? Other than by "it don't work so buy another"

Any other ideas would be supa-welcome.


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