I did the resistance check on my ohm meter to test the glow plugs. Four of them were between 1.4 and 1.6. The other one was open. Has anybody got readings like this before. I was told if it was above 1.2 to replace them. What do you guys think?

1984 300d Turbo 140,000
Replace All If One Is Open, Use Reamer To Clean Holes For Better
Heat Of Tips

A good glow plug should measure about 0.6 ohms cold using an accurate ohm meter. It not unusual for your readings to be slightly above 1.0 ohms if your ohm meter is a little off. I would not replace all the glow plugs as suggested above if you only have one bad one unless I knew they were very old or if I had no idea how old they were. Now if you've got to go through a lot of effort to get to the one bad one and all the others are sitting right there waiting for you to replace them, then that's another story.

Len

chosen,

A '84 300D has the 617 engine so the GP are relatively easy to change. Even easier if U get a 12mm ratching combination wrench.

U also need an 8mm wrench to loosen the GP terminal nut. Be careful U don't loose it. New GP don't come with a new nut.

I suggest U cut the terminals on the end of the GP cable to "spade" terminals. That way U can install the wires as the last step and U won't have to put terminal nut on with the GP in the head. I.E. U install the terminal nut before installing the GP in the head and install the wire as the last step.

I would only replace the 1 GP that is bad. Measure the resistance of the new GP in and out of the engine. Compare these readings with the readings of the other GP. I suspect the other 4 are OK and do not need to be replaced.

Always carry a spare GP.

P E H

I assume you mean a 617 engine, but I agree with only changing them as the fail unless you have some reason to believe they have a problem. They are very easy to replace on a 616/617. Personally, I wouldn't mess with the connectors, if you're worried about losing the GP nuts just buy some spares.

Craig,

Yep, I meant a 617 engine. (I edited it). I was thinking of the W number of my 300SD.

I've done the "spade" modification years ago with no associated problems.

The modification is more of a change to make it easier to change the GP than it is to prevent lost nuts. I will do it to any 617 type any engine I get. The biggest advantage is that I can use the ratchet combination wrench with out taking off or putting on the terminal nut with the GP in the head.

MB solved the lost nut problem on the 603 engines. But caused many more problems by putting the GP under the intake manifold.

P E H

It sounds like the "spade" modification would work fine, I've just never had a problem with those nuts, maybe I just have small enough hands. I can usually just spin the GPs in by hand and use a short wrench to tighten them. I seem to average a couple per year between my two cars.

That's friggen' brilliant. Just got my reamer in. Can't wait to change out those terminals!

Bill

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1998 E300 +310,000K
1996 E300 +460,000K