83 300D Glow Plug Question

After a cold start, it runs rough for 1/2 minute before smooting out. Also, lately the dash glow light has not been working - I thought the bulb was out. I have the pen type glow plugs and tested their resistance at the glow plug connector (at the timer relay). All had similar resistance except one which was much higher than the rest. Interestingly, while the glow plug connector was disconnected from the timer relay, I turned on the key - and the dash glow light worked. I re-connected the glow plug connector, and the dash glow light stopped working again. Weird. Ya'll please help. Thanks.

ransky,

Was the plug with high resistance the number one plug? If so, this is probably your whole trouble. The relay measures the changing resistance of the number one plug and uses this to determine when to turn off the dash light.

My experience in the past has been that if the glow plugs are a few seasons old, just replace all five. This is usually a miracle cure.

Also the resistance measurement does not tell the whole story with these plugs.

Good luck,

Thanks Larry, I believe it is the # 1 plug. I'm going to replace them all.

FYI It was the #1 glow plug. I changed it, and the problem was solved. The dash glow light works and it starts and runs smoothly.

I was going to replace all the glow plugs, but I didn't. I admit that I cheaped-out. The thought of fixing my car for only $15 got the best of me. I tell my Son "a job worth doing is worth doing right", and that shortcuts can come back a bite you in the butt. I didn't follow my own advice. I hope I don't get bit.

ransky,

I have done this before and gotten by with it. At your convenience and when there's a few extra bucks in your budget, order four glow plugs from the parts shop here. They have a better price than what you paid. It will take a little time, but you will have them, and you can replace them at your convenience. It will take some time to put in the rest of them. The back two are particularly hard to get at without pulling the injector lines(I call them "the spider". Replace them at your leisure and then you'll be in good shape.

Good luck,