Hi,

I just bought an '87 300D. In the morning (not cold, I'm in Texas) the car needs maybe 5 seconds of cranking over to start, and then it idles very rough until I have driven it a short distance and it is warmed up a little. During this rough idle, it has lots of misses it seems like. The guy that did my pre-purchase inspection said it was due to worn injectors. Does that seem reasonable? Can I replace them myself (light DIY skills) or should I pay someone to do it? Also, the glow plug light flicks on for only a fraction of a second (not the usual 5 seconds or so). Does this mean the indicator light is malfunctioning, or does it mean the glow plugs need to be replaced? Thanks a lot for your help.

Loren:

Sounds like a pre-glow issue to me. The glow plugs can be check one at a time using a standard multimeter. Look for high resistance across one or more of the plugs. The glow plug light not staying on for several seconds is a feature to let you know there is a plug problem.

Take it to someone other that the guy that did the PPI if you do not feel comfortable doing it yourself. I can guide you through the troubleshooting if you like, although I do not have the manuals for the W124.

Going ahead an replacing all the glow plugs is another option some may recommend. I generally wait for a plug to fail prior to replacement. Plugs are around $10 each. I recommend Bosch.
-Scott