The plugs i took out were Bosch. Unfortunately, Bosch was the only brand i could find at any of the chain stores in the area. So that's what I was forced to put back in. I guess if I find any of a good brand I should jump on them and have them waiting for next time.

And Yes, It does start like a dream.

Now if i can just get my blinker switch replaced and a broken fog light lense replaced I can pass the state inspection in a few months.

The 240D shold have the same 80A fuse. One of those who know should chim in about this.

Thanks,
C

There is nothing wrong with Bosch, AFAIK. That's what is in these two.

Are you sure that all five of them were NG? All five were open? This would be almost unbelievable.

I say this because you would struggle mightily to start the vehicle without any functioning glow plugs, and your initial post mentions that your wife noticed that it was harder to start. It sounds like a couple of bad glow plugs, but, for all five to be out is unlikely.

Before you toss them out, check them again with the meter. See if you can get a resistance value on any of them from the attachment point for the wire to the outside case.

Well, I'm pretty sure none of them are any good. When I took them out I noticed that all of them had a lot of soot built up on the tips. I guess my description of "harder to start" could be a little better. In good times, it starts imediately. Almost before the key is all the way forward. A few months ago (probably 4), the GP light started to only flash. A few weeks ago the Gp light stopped working all together. We would have to crank the engine for 10-20 seconds before it would fire off. From what I'm told by a diesel mechanic friend who helped me replace the water pump a couple years ago, the car has excellent compression. He almost couldn't believe how good the compression was.

I'll recheck the plugs and make sure. Wo knows, maybe I'll be able to keep one as a spare.

OK, that changes things. If you have to crank for 20 seconds in relatively warm conditions you certainly have more than two bad plugs.

But, all five going bad within six months.

Lately it's ranged from 50-80 degrees.

"withing six months" This is why I didn't like putting Bosch plugs back in. Maybe I just got a bad lot on the first go-around.

Brian,

I have about the same problem as cmichaleik and was wondering if you might comment on it.

My gp light does not come on in the pre-start position but does come on when I go to the start position.

Secondly, I can't find the gp relay. I have a 1975 115 300D. The electrical diag. says that it is under the steering wheel kick panel but I can't for the life of me find it. I know what the relay looks like but can't seem to see it there. A local MB buff said that the one in his 115 300d was located on the left front side of the engine compartment. No luck there either.

The po had a new relay installed about 14k ago so I am hoping that the problem is not there. Since the light comes on when the key is turned to the start position I doubt that it is the relay. Could it be something wrong with the key in the pre-start position?

Any help[ is greatly appreciated.

Kip

I don't have any experience with the W115, but offer my thoughts based upon the W126.

The easiest and most likely culprit when the light starts to malfunction are one or more than one glow plug. Normally, you can test the resistance of each glow plug with a suitable meter by removing the plug from the glow plug relay and testing each pin. However, IIRC, the older vehicles have the series type glow plugs so testing resistance of each plug is not possible using the conventional methods.

I would prefer if someone with some specific knowledge of the W115 would comment, however, you can certainly test each glow plug if you disconnect the wires to the glow plug and attach the test leads directly to the plug and to ground. You are looking for one, or more than one, of the plugs to have a reading of infinity (meaning it has failed with the element burned out). Change any of them that have this infinite resistance.