Car starts harder than it should and is rough first couple minutes and GP light comes back on. Read the trouble codes and they pointed to the 5+6 GP's Followed Dieselgiants instructions on checking the GP's on my car. Here is the situation, his instructions say to connect the negative lead from the meter to the negative post on the batt. In the 210, the batt. is under the back seat. Can I just use part of the frame or motor as a ground? Doing it this way I got the following readings on my analog meter: GP's 1-4, O ohm (I was looking for ~.5 or so). When connected to 5+6 I got infinity. I gather 5+6 are my bad plugs. But why would the first 4 read 0? Because I didn't have sufficient ground? Or would this be normal for an analog meter. BTW the meter has ohm adjust and was zeroed prior to the test. Am I correct in concluding that 5+6 are bad the the other 4 are OK?

TIA, any help is appreciated.

__________________

Muleears
'07 E320 Bluetec 133K my DD
'04 Jaguar XJ8 VDP, 34K
'10 Hyundai Accent 60K Grocery Getter
'02 VW Golf soon to be on the road again
'97 E300 Diesel Son's DD
'61 VERY tolerant wife

Hampton Roads, VA USA

Gone but not forgotten:
'67 250S 95K
'86 300SDL
'87 300D Turbo, 364K! R.I.P.
'98 E300 Turbodiesel, 213K
'02 S420, 164K
'01 Prius 138K

The block is actually better than the neg. term on the battery. I'm thinking that your meter is not set sensitive enough to read .5 Ohm. What setting did you use?

You should use the lowest Ohm setting available. Remember to keep your fingers off the lead as it can effect the reading.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

Code P1369 means either 5 or 6 is bad. I would doubt that both are bad. The resistance reading for a glow plug is 3 ohms perhaps, so if your ohmeter is set to a high range, it may just show up as zero. A bad GP will read infinity. It's like a light bulb...it's either good or bad. Any metal that is connected to engine or frame is good to use as a ground.

__________________
Mark in MA
05 MB E320CDI 402k Granite Grey Metallic
05 MB E320CDI 267k Black
05 MB E320CDI 232k White
05 MB E320CDI 209k Tectite Grey
99 Dodge 2500 Cummins 5sp 148k
62 Jeep CJ-6 120k

Yes, my original digital meter is MIA so I bought a cheap analog one that only has one range for ohms, so you're right, it probably cannot show me .5 ohm. The car starts bad enough to be missing two plugs. From cold it won't start first try (on its own). So I give it a little pedal and hold the starter on a little longer and she fires up, very lumpy but it runs.

Why would I get infinity on 5+6 if they both weren't bad?

__________________

Muleears
'07 E320 Bluetec 133K my DD
'04 Jaguar XJ8 VDP, 34K
'10 Hyundai Accent 60K Grocery Getter
'02 VW Golf soon to be on the road again
'97 E300 Diesel Son's DD
'61 VERY tolerant wife

Hampton Roads, VA USA

Gone but not forgotten:
'67 250S 95K
'86 300SDL
'87 300D Turbo, 364K! R.I.P.
'98 E300 Turbodiesel, 213K
'02 S420, 164K
'01 Prius 138K

For an inexpensive analog meter, "zero" is about as good as you're gonna do on a good glow plug. My 606 glow plugs measure about 0.6 Ohm on a 5-digit Fluke 8800 meter. Infinity usually means a bad glow plug but if you are measuring from the plug at the pre-glow relay could also mean a bad wire. Measured from the tip of the glow plug to the block, infinity definitely means a bad glow plug.

It's unusual for two to fail at once so probably what happened is that one failed but the pre-glow relay isn't always sensitive enough to pick up just one bad one. Later, a second one failed and now you get a warning from the system.

In any case, it does sound like you have two bad glow plugs. Since replacement pretty much requires pulling the intake manifold, you may want to replace all six, especially if you will be paying someone to do the work. Personally, I don't find pulling the IM to be all that difficult so I just replace the bad glow plug and leave the others alone. YMMV.

BTW, be extra-careful pulling the glow plugs from the 606 head. This forum is full of "I broke a glow plug" threads for the OM606, read some of them. Consider reaming out the hole and put a little anti-seize compound on the new glow plug.

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

If both 5 and 6 read infinity then they're both bad...just quite a coincidence.

Like I said on your previous thread...PB Blaster, warm engine, torque wrench...those are the 3 keys to success when replacing 606 GPs.

__________________
Mark in MA
05 MB E320CDI 402k Granite Grey Metallic
05 MB E320CDI 267k Black
05 MB E320CDI 232k White
05 MB E320CDI 209k Tectite Grey
99 Dodge 2500 Cummins 5sp 148k
62 Jeep CJ-6 120k

HF usually has a DMM on sale for $3.99. Mine measure .6 Ohm like Jeremy's when good.

Check wiring connections to both GP's. Could be loose.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

These GP's have been in only about a year, maybe 20K miles. Went through the stuck plug fiasco when we changed them. Only one came out the way it should.

I think Jeremy had it right with the one plug then another theory. It began to stumble on startup a month ago, but now it is very bumpy.

__________________

Muleears
'07 E320 Bluetec 133K my DD
'04 Jaguar XJ8 VDP, 34K
'10 Hyundai Accent 60K Grocery Getter
'02 VW Golf soon to be on the road again
'97 E300 Diesel Son's DD
'61 VERY tolerant wife

Hampton Roads, VA USA

Gone but not forgotten:
'67 250S 95K
'86 300SDL
'87 300D Turbo, 364K! R.I.P.
'98 E300 Turbodiesel, 213K
'02 S420, 164K
'01 Prius 138K