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Time to call in the experts
If you have any ideas on how to help I would be most appreciative. I know "search is my friend" but I have been pretty methodical about this and been working on it all week and cant get it figured out. I feel like I have tried everything I know on this and still no "glow plug joy". There are copies of diesel discussion threads laying all over my garage with greasy handprints on them but the car is still not working correctly. Last weekend children left the doors open on the 1991 300D for several hours and drained the (one month old heavy duty) battery. After jump starting the car off of someone elses I started having glow plug issues. (Light on for a few minutes when driving and then the next day not coming on anymore at start). My car has always started immediately in the past and has pretty decent compression. After getting home later I tested the alternator and battery and system is charging fine. Battery voltage with everything off is ~ 12.7 volts and in the 13.6-13.8 range when car is running. Step one: I pulled the manifold (fun!) and bought five new Beru glowplugs. While the harness was disconnnected I tested it for continuity like shown on the Diesel Giant forum and wires were fine. After getting everything back together, still no glowplug light on start, and the car will eventually start on no glow plugs, runs great once warmed up. Its been about 60-70 degrees outside this week. I did ream the holes when plugs were out and they were actually not too bad from what I could tell. I tested all glow plugs new and old for continuity and found one old bad one, did not bench test the new ones with jumper cables to see if they would actually glow because I forgot and put everything back together. Step two: I thought the problem now lay in the relay so I bought a new one from ******** and when I installed it, the glow plug light came on for a few seconds (dimly) and then blew the 80 amp strip fuse on the first start. Step three: I went through the engine compartment and cleaned and retightened all ground straps I could find (about three on the strut tower and one underneath the car on bellhousing). They all looked okay but I cleaned them and put back on. Battery cables are clean and tight. I found some groundstraps under both headlight assemblies that were pretty corroded, so removed the wires, drilled new holes, reground them and then painted everything with rustproofing paint. Step four- I pulled the instrument cluster today and all wires on the back looked tight and clean- no missing/disconnected wires I could find, and I also replaced every single fuse in the fuse block underhood. I also retested everything I could with the manifold still on. Im off to Napa in a few minutes to find another strip fuse (or five), but I have a feeling they will blow also! As long as the engine is warm I can drive around, but tommorow will have to repeat the process, and I know once it gets cooler this Fall I will be stuck somewhere (and always draining battery/starter with long start attempts). Any ideas diesel gurus? My wonderful car has me stumped and very frustrated at the moment!
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1991 300D 2.5 turbo 1991 560 SEL 1987 911 Toyota landcruiser Atlanta, Gawga Last edited by mtbguy; 09-21-2009 at 12:16 PM. |
#2
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I have no clue but a question to consider. In 1991 did they include a cut off circuit to kill the power if a door is left open for a long period?
Looks like the problem should be simplier than your attack.
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Charles 1983 300D, bought new, 215k+ miles, donated to Purple Hearts veterans charity but I have parts for sale: http://www.peachparts.com/shopforum/mercedes-benz-cars-sale/296386-fs-1-owner-83-mb-300d-turbo-rebuild-parts.html |
#3
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I'm not sure- I know when I got back to the car three doors were open, the trunk was open and the interior dome light had also been turned on. I was quite angry because this happened of course 40 miles from home outside of town. The lights were on still just very dim. Luckily I had jumper cables and some tools in the trunk.
The ignition switch has always worked fine, and key turns easily, now i am wondering if I should replace it. Hopefully that is not hard to access- I have not researched removal/replacement on the forum yet.
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1991 300D 2.5 turbo 1991 560 SEL 1987 911 Toyota landcruiser Atlanta, Gawga Last edited by mtbguy; 09-19-2009 at 04:40 PM. |
#4
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Sounds like either a glow-plug is shorted (defective?) or a glow-plug wire is shorted.
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Gone to the dark side - Jeff |
#5
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After reading your first post, I don't find you mentioning charging the battery with a charger, it sounds like you just jump-started it and kept driving.
After a complete discharge like you had, the battery needs a full charge, put it on the battery charger on the 2 amp setting overnight, then load test it to make sure it is ok. If you are blowing the 80 amp fuse, it sounds like you put in a bad glow plug, a bad relay, or maybe one of the glow plug wires has damaged insulation causing it to ground out on the engine somewhere. You could diconnect the connector that goes to the glow plug wires from the relay, then turn the ignition on and see if the fuse stays intact, this way you could rule out some internal fault in the new relay. You could also connect a fused jumper lead to the battery positive post and probe each of the glow plug wires at the connector, the on that blows the fuse will be the bad lead/plug. You would want to use the same gage wire as the glow plug lead and probably at least a 20amp fuse, I would think. Just some ideas, hope it will help. |
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Quote:
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1991 300D 2.5 turbo 1991 560 SEL 1987 911 Toyota landcruiser Atlanta, Gawga |
#7
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Your '91 should have a glow plug relay without the 80 amp strip fuse. It has a circuit breaker type reset that will trip and reset itself automatically.
I know if you look it up it shows the fuse type relay, but it was upgraded for the '90 model year forward on the 124.
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1987 300TD 309, xxx 2.8.2014 10,000 mile OCI Be careful of the toes you step on today, as they may be connected to the ass you have to kiss tomorrow. anonymous “Be who you are and say what you feel, because those who mind don’t matter, and those who matter won’t mind.” Dr. Seuss |
#8
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Yeah- Im wondering about this. The original relay did not have the strip fuse. The replacement one from ******** looked identical except that it does have the strip fuse.
I'm wondering now if the old one was actually still okay and I'm throwing parts at it. I'm back to testing the plugs and wires again tomorrow. I wonder if I got a batch of bad plugs from the vendor. They ohmed out fine but I didn't do a vise test where you hook jumper cables up to them to make them actually glow.
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1991 300D 2.5 turbo 1991 560 SEL 1987 911 Toyota landcruiser Atlanta, Gawga |
#9
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Quote:
Out of curiosity I connected a single Glow Plug (from a 617) in series with and Automotive Type Ammeter (like you would mount on your Dash Board). I applied the threaded area of the Glow Plug to the (-) terminal and the other end of the wire coming out of the Ammeter to the (+)Terminal. The results were that the current pegged the Ammeter at 60 amps (as high as the meter goes) and as the plug got Yellow Red hot dropped down and settled down to about 16 amps. So even one Glow Plug would easily burn a 20 amp Fuse when the current first flows.
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84 300D, 82 Volvo 244Gl Diesel |
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Okay, so I will try at least a 60 amp fuse and probably get an 80 amp one also for my jumper wire testing tool.
This will be a good diagnostic tool to keep for the future also. I'm starting to think that the insulation may be bad on one or more of the glow plug wires, because previous owner had that happen once before and his shop replaced just one wire rather than the harness. Maybe they tested fine when the harness was out of the car, and then once bent back in place there is a short. I thought because I had a 1991 year model they were more immune to the biodegradable wire insulation problems of 1992-1995. I guess not!
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1991 300D 2.5 turbo 1991 560 SEL 1987 911 Toyota landcruiser Atlanta, Gawga |
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Keyboard trouble shooting at its finest. All the suggestions sound good but I need more information to help. Couple of questions??? What happened to the old battery? Why did you change it out? Anything weird going on with it or was it juts a natural death? What happened when you put the new battery in? All systems go or anything weird? I ask this of the forum members, is it normal to drain a new battery in an MB with a couple doors open for a few hours? I would think these batteries would go for days with just doors open. The reason I ask is I want to take the blame away from the children and the event and see what was really happening that took out the old battery and took out a 1 month old battery. Does this make sense. Thanks
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83 300D 227,xxx miles, sold 86 300 SDL 130,000 miles, sold |
#12
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The old battery died a natural death. I think the new one was not getting a good charge from the alternator because previous owner had an old disconnect switch on the negative terminal which was dirty and corroded. (I removed the battery disconnect switch the night we jumped the car and it has been charging fine since then.
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1991 300D 2.5 turbo 1991 560 SEL 1987 911 Toyota landcruiser Atlanta, Gawga Last edited by mtbguy; 09-20-2009 at 02:54 PM. |
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Quote:
With the harness out of the car, it acts as if it has a short. Sometimes I get continuity out of it, and sometimes not, depending on how you bend the wire around. The # 5 glow plug tested and glowed fine. I bought solder and heavy gauge copper wire which is thicker than the OEM gauge. I am starting to make a new harness in an hour or so. Thanks for everyones help so far. I believe this will turn out to be the problem, I'll let you know if it works!
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1991 300D 2.5 turbo 1991 560 SEL 1987 911 Toyota landcruiser Atlanta, Gawga |
#14
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Glad you are making some progress.
Thanks you Diesel 911 for correction on the fuse amperage, BTW. |
#15
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Urkgkk,Urkgkk...
What's the Manufacture date stamped on the Driver's door post?
(A Late 1991 MAY have been "Gifted" with the Automatic Involuntary Self- Degrading Engine Wiring Harness Option...I Hope Not!)
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'84 300SD sold 124.128 |
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