Glow Plugs, what I learned.
 

Having some trouble starting the 82 240D early this fall. Had the valves adjusted, but did not seem to help much. December 4th, left it parked for 2 weeks for a business trip……and no start when I got home. Ambient temp in the 30’s. Suspected the battery, but really it was cranking fine, so I kept it charged up while trying to get it to start. . I had checked the glow system and all seemed to check out (power to relay, power from relay, ohms at plug, etc.)

Things I did:
Changed primary fuel filter, some light crud.
Changed secondary filter.
Checked for fuel flow at all injectors, positive while cranking.
Tested ohms at each plug, all less than .5.
Tried the cabin light test……AHH-HAA, no dimming of lights while glowing.

The cabin light test is what got me going. Bought 4 Bosch plugs at A-Zone and put a new one in the vise and tested it with the battery charger. The new ones get hot fast! Red hot!

So, I removed the fuel line rack, for access, and started to remove the plugs. Be careful here, the wires want to stick to the little nut and twist the connector off. Use some PB Blaster to loosen things up before starting.

I tested the old plugs one at a time as I removed and replaced them. NONE would even heat up. Two showed OK on ohms on the bench, two did not. I can not explain this; maybe I am too dumb to use a meter?

Got it all back together and it started right up. My skills are limited, but this only took about 2 hours once I got going. This is the first work I have done other than changing the oil, outside of some interior stuff.

Bottom line: I am now on the cabin light team for testing. I am also on the change the plugs on a schedule team. Even if I change them every 2 years, that’s only $1.70 per month. Cheap insurance.

Merry Christmas to the forum for all of the details I gained searching on the problem and the excellent troubleshooting and repair advice I found.

Clay

"maybe I am too dumb to use a meter?"

Me too:) Ive had ones test good with the meter but be bad. I now remove each plug and test it by hooking it up and see that it glows fast and hot.

Same here. All the old ones I tested read exactly the same as the new ones, 0.6 ohms after correcting for wire resistance. The old ones glowed just not as quickly. A new set will make a world of difference.

Glow Plug Follies
 

I had a similar experience -- cool weather, car would NOT start without exhaustive cranking --- all plugs had proper resistance, had power, light on dash worked --- didn't know about the cabin light scheme ----- just figured that somehow, the tests were missing something. I was leaving a trouble light under the hood for heat, so the car would fire the next morning. Replaced the plugs .... car started right up, & still does.

Also, from my experience, don't buy the cheap Autolite plugs. I bought a set and had two fail within two months. Once again, it was a no-start.
Ben