'83 300D Turbo - No glow plug indicator light, excessive crank, hard start only when cold. Tested relay plug, found 2 glowplugs registering 2.3 and 11 ohms (0 for other 3). Can 1 or 2 weak plugs cause the whole curcuit to be non-functional? The plugs and relay were all changed 30K miles ago (Bosch). Are the plugs numbered 1 through 5 from front of engine to back? Should I replace all 5 again? Should I replace with BERU? Thanks!

Not on yours. Each glowplug functions on its own. Did you test the strip fuse and make sure they are getting power. I'd be inclined to replace all five. PEH would only replace the bad ones.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Yes, checked voltage at battery, "hot" to relay plug, both sides of the strip fuse. Could be those two plugs with more than an OHM could be causing the issue.

Noticed you have an Atomic 4. Had one for 22 years in a Cal 2-27. Ran great, but ONLY if I used Marvel Mystery oil in the gas. Thanks!

0 ohms is odd. There should be some resistance I think.

Yes, Marvel Mystery oil. Got to keep those valves from sticking.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

A couple of bad GPs will be noticeable in the cold, even if the others are OK. Your measurements are funny; the good ones should be around 0.6 ohm when cold, the bad ones are usually infinity. I would probably replace them all (bosch or beru are both good), just to get a good baseline. They are numbered front to back on the engine. The light should work after you replace them.