85 300D more glow plug problems/ohm questions - PeachParts Mercedes-Benz Forum

#1 01-05-2009, 06:55 AM

Hi all 1985 300D still having glow plug problems, replaced glow plugs and glow plug relay, still no gp light and now the ohms on all the wires reads 1.65 this seems high but they are all 1.65 exactly would the wires be my problem? or is it something else. The relay is getting plenty of juice. Any advice/help would be great thanks!

#2 01-05-2009, 07:24 AM

Hello anyone? anyone at all?

dannym · #3 01-05-2009, 08:21 AM

Have you checked the bulb?

You didn't mention if it's hard to start. Are you having starting problems?

How are you testing? Putt he meter on 200k and go from the glow plug socket to the battery ground.

Danny

pelon · #4 01-05-2009, 08:24 AM

the glow plug light bulb is out.
i assume the car won't start?
the place you are grounding the ohm meter may make a difference on the reading. are you grounding it on the body? that could give you another half ohm due to dirty ground between the motor and body.
they are all the same so that's what came to mind. or your meter is off by half ohm.
are you getting power at the plugs? at least 11-11.5 volts?
r

#5 01-05-2009, 08:29 AM

Oooopppss sorry yeah the car is hard to start and there is the unburnt fuel coming out the tail pipe. Hmmm didn't think about the dirty ground thing. I will go home and test the power to them, and find a better ground. But they should be getting power. New glow plugs and all.

tangofox007 · #6 01-05-2009, 08:34 AM

Quote:

Originally Posted by helpplease

...and now the ohms on all the wires reads 1.65 this seems high but they are all 1.65 exactly

There is something wrong with that picture.

#7 01-05-2009, 08:48 AM

Quote:

Originally Posted by helpplease

there is the unburnt fuel coming out the tail pipe.

That will also make starting much harder.
http://en.wikipedia.org/wiki/Flooded_engine

#8 01-05-2009, 08:56 AM

What might be causing it to flood? I haven't been pressing the pedal or anything before I start it. It just takes a long time craking on the motor to get it to run. My other diesel 83 300CD starts right away (unless its really really cold). I do plan next week to replace injectors next week hopefully.

pelon · #9 01-05-2009, 09:25 AM

what exactly you mean? were did you measure this?
i'm assuming you put a new relay? and your fuse is good?
try measuring the ohm on the glow plug itself with the glow plug plug disconnected at the relay. then connect it and measure the volts on the plug. it should show 11+- and go up in about 5 seconds to 12.
i just cleaned the contacts in my relay and it made a BIG difference. started right up this morning at 18F. if your relay was a used one,,, maybe?
r

#10 01-05-2009, 09:33 AM

no bought a new relay and the fuse is new as well. I will try measuring them again after cleaning contacts tonight and see what numbers I get I will post them tommorrow thanks for all your help guys!!!!

vstech · #11 01-05-2009, 09:34 AM

another thing you could be seeing... some ohm meters have a peak lock button, make sure you can read 000 by testing the leads to themselves. if it reads anything but 000 when you touch the leads together, add that number to the total readout you get.

#12 01-06-2009, 07:11 AM

okay update retested using diesel giants methods and now the #4 glow plug is reading 55.7 ohms and this one is NEW and a Beru not a autolite pos. so anyways will wait a few days and then get another one and test again.

dannym · #13 01-06-2009, 07:25 AM

What setting are you using on the meter?

#14 01-06-2009, 07:27 AM

same one as diesel giant 200 ohm i think the others were 1.2 ohms once I adjusted for the wires and all.

Jeremy5848 · #15 01-06-2009, 12:24 PM

Glow plugs are like light bulbs in that every once in a while you find a bad one from the factory. They all should have been tested as part of the manufacturing process but one may have slipped through.

Once you have found what appears to be a bad one by measuring between the multi-pin plug and ground, confirm it by measuring at the glow plug itself, in case the wire is damaged. Final check is with the "bad" glow plug in your hand.

Jeremy