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  #1  
Old 09-30-2008, 10:25 PM
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Glow Plug Light, not lighting up, engine cranks but won't start

I have a 1985 300 SD that I have been commuting with for a few months now. Yesterday morning I drove it to work, when leaving work I noticed the Glow Plug Light did not come on as it usually does. I also noticed a buzzing sound from the engine compartment. After turning the key (after the seatbelt alarm went off) the engine cranked but would not start. A friend had some starting fluid which we squirted very little into air intake. Tried a number of times to start it, with a few more small squirts we got it going. I drove it home (40 mi) and got it into my driveway. Turned the engine off, waited about 30 seconds and tried starting it again. It did start, and I am pretty sure I had that buzzing sound from the relay. This morning it would not start and after a quick inspection of the glow plug relay box, I noticed that the 80 amp fuse was a bit buckled. It has a hump in the metal, about 8 mm above it's original flatness... Any suggestions on what to check first?

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Old 09-30-2008, 10:47 PM
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The fuse needless to say with an ohmeter. Or with the ignition on 12 volts on each side of it. If it is open check for a plug with a dead short. You can read the individual plugs through the harness connections. Good plugs will read perhaps an ohm or so a dead shorted plug will read zero resistance pretty well. No shorted plugs? The fuse could have died from just old age. Thats a start. During the check of the plugs keep an eye open for any glow plugs that read infinity or high resistance. They are shot.
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Old 09-30-2008, 11:37 PM
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I'm good with mechanical work, but electronic things, not so much. Can you or do you have time to explain those test with more detail? I do have a multimeter. I will get a new fuse tomorrow and replace it after work. Can I loosen the two nuts on the fuse, remove it and replace it without disconnecting the battery? Or is it best to disconnect the battery first.
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Old 09-30-2008, 11:57 PM
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On my 77 300d, I think there was a plastic ridge behind the fuse which made the fuse bulge in the middle for a purpose. It's pretty easy to check the continuity of the fuse with an ohmeter but I wouldn't take the bulge to be an indication of a problem. It could be just one or more bad glow plugs.
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1985 300TD 185k+
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1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
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Old 10-01-2008, 01:28 AM
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80 Amp Fuse

AD tells us that the "Bulge" in the fuse is good...Allows some flection of the
metal without breaking under the heavy Amp/Heat loads it carries.
If you were to tighten down the two fixing screws with the Fuse "Flat and Tight"
there would be no flection room and the Fuse's lifespan would be shortened.

An Unsolicited Recommendation:
Using "Ether", "Starting Fluid" , Etc. WILL BURN OUT GLOW PLUGS!
It also is not healthy for your "Loaded","Driven" engine components.
(Look up the Energy Release Coefficient Differences of "Ether" and Diesel)
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Old 10-01-2008, 08:43 AM
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An Unsolicited Recommendation:
Using "Ether", "Starting Fluid" , Etc. WILL BURN OUT GLOW PLUGS!
It also is not healthy for your "Loaded","Driven" engine components.
(Look up the Energy Release Coefficient Differences of "Ether" and Diesel)

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yes, I was forwarned about the starting fluid and really used only a wee teensy bit of it to get the car going and get it home.

any details for my electric tests mentioned earlier in this thread?
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Old 10-01-2008, 02:23 PM
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To test glow plugs with on ohm meter, unplug the connection at the relay, you'll see female pins numbered 1-5, touch the red lead to #1, and the black lead to a ground, I use the bolt holding the relay to the inner fender.
Repeat for each plug. Ideally, less than one ohm, however, my CD reads 1.7 each, I need to install new ones before winter. right now it stumbles a bit when first started.
Attached Thumbnails
Glow Plug Light, not lighting up, engine cranks but won't start-glow-plug-p-cropped.jpg   Glow Plug Light, not lighting up, engine cranks but won't start-glow-plug-g-cropped.jpg  
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Old 10-01-2008, 02:42 PM
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Interesting that it "wouldn't start" without starting fluid. I know from experience that my '83 240D will start at temps above freezing without the glowplugs. It won't like it but it'll start. Grind on that starter for 20-30 seconds and she should go.

Have you ever replaced the glowplugs? I'm a shotgun man in this respect, I'd replace all the glowplugs and the fuse right now. Better to do it now while its warm out than in Feb at -20F... I'll be replacing all the glowplugs in my 240D this weekend.
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  #9  
Old 10-01-2008, 10:16 PM
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Thanks for the info and photo's. I will test things out tomorrow and probably replace the glow plugs as well. Saw a step by step test on dieselgiant.com for glow plugs, so I'm loaded with new learning. Never replaced the glow plugs in this vehicle. I had suspension problems and vac problems to deal with when i bought it. Corrected them and have been merely changing oil and filter till now.

What's the tuneup list for 300,000 miles? I am approaching that number real soon.
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  #10  
Old 10-03-2008, 07:10 PM
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Well, I changed out the glow plugs and fuse. Still no indicator light.

I then removed the negative cable on the battery, just in case, and removed the glow plug relay, off the fender. Opened it up and looked around inside the box. Found that one contact on the metal plate that is held in tension by a small spring had alot of black buildup on it.

After sanding it and it's mate, I reassembled the relay box, reinstalled it and the car runs.

The buzzing sound was probably the other set of metal contacts bouncing off one another... I figure...
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  #11  
Old 10-04-2008, 04:11 PM
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Use of Starting fluid

Here is some good read on the use of starting fluid.

www.peachparts.com/shopforum/showthread.php?t=85676

Ether use and abuse "flame suit on"

charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works
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