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#1
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Glow Plugs 1985 300SD
Hello Everyone,
I have done some research and did a few checks on my car, but once again it is getting pretty cold around here, 5 degF for the next few days, and I need to try and get this figured out. Lately, the glow plug light has been working intermitently, now it hasn't worked in the past few days. I have done the following checks: 1. 0 ohms on every glow plug, from relay to glow plug 2. Voltage at each glow plug wire output on the relay (12.42 V) When I unplug the glow plug wires from the relay, the light on the dash comes on like normal. When I plug the wires back in, the light does not come on in the dash. I tired this multiple times with the same outcome. Is it possible that there are 1 or 2 glow plugs which are shorted out? I am wondering if the relay is an issue or if there are other ground wires which might need to be cleaned? I don't have an electrical schematic at this point in time. Any help is greatly appreciated. Thanks, Keith
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1985 300SD 200K |
#2
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Where, exactly, are you measuring the reported zero Ohm resistance?
If you do not attempt a start, how long does your GP relay remain closed?
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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl. |
#3
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Is this resistance test being performed with a digital or very high quality analog meter? What resistance range is the meter set to when the zero ohms reading is obtained?
If you are correctly reading the resistance on these glow plugs, then the reading suggests that all of them are bad.
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'79 240D |
#4
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I have found that the best way to check the glow plugs is this: Take a jumper wire and connect one end to +12v. Remove the glow plug wire harness from the relay, and touch the other end of the jumper wire to each of the glow plug terminals in the plug. If it makes a little spark, the plug is good. No spark, the plug is bad. It is just that simple. I have found using a meter to be very unreliable. Even some plugs that check good with a meter, are bad with this test. Of course the best way to check is to remove them and apply 12v directly, and I do that anyway after replacing the bad plugs just to be sure....Rich
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All Diesel Fleet 1985 R107 300SLD TURBODIESEL 2005 E320 CDI (daily) LOTS of parts for sale! EGR block kit http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html 1985 CA emissions 617 owners- You Need This! Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst. Sanden Instalation Guide (post 11): http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html |
#5
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Quote:
The voltage reading at the relay pretty much indicates that it is functioning. A quick test of resistance through the plugs may or may not turn up a problem, but that's really the important step. Check resistance between each glow plug and ground, looking for readings over 1 ohm, zero, or infinite resistance, as evidence of a bad plug.
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'79 240D |
#6
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Quote:
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85 300D turbo pristine w 157k when purchased 161K now 83 300 D turbo 297K runs great. SOLD! 83 240D 4 spd manual- parted out then junked |
#7
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Quote:
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85 300D turbo pristine w 157k when purchased 161K now 83 300 D turbo 297K runs great. SOLD! 83 240D 4 spd manual- parted out then junked |
#8
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I have not experienced that. In fact, the spark is so small that it is barely visible. I am sure it is not enough to damage the terminals in any way.
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All Diesel Fleet 1985 R107 300SLD TURBODIESEL 2005 E320 CDI (daily) LOTS of parts for sale! EGR block kit http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html 1985 CA emissions 617 owners- You Need This! Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst. Sanden Instalation Guide (post 11): http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html |
#9
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Rather than directly connect the glow plug to power (which should be done through a fused circuit for safety), I use a test light to B+. The light should light brightly for all five plugs. Dim or off indicates faulty plug. Note that each plug must be tested independently of the others in the harness.
HTH
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When life gives you lemmings... make lemmingade. |
#10
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The Ohm Meter is suposed to set at 200 Ohms on the Meter setting/Dial
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84 300D, 82 Volvo 244Gl Diesel |
#11
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Everyone,
Thanks for the quick response. I forget what setting I was on for Ohms, but I will re-test and I ordered 5 new plugs so I can just swap them out when I pull them out for testing. Thanks, Keith
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1985 300SD 200K |
#12
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Ive had a glowplug short out in one of my cars.The strip fuse kept popping till I tested to see which gloplug was bad.Put a new plug in and all was good..
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#13
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You're right, I forgot about the fuse. I have never experienced a shorted glow plug. My guess is that kind of failure is 1000 to 1 or higher. Do you still have the shorted glow plug? I'd love to examine it.
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85 300D turbo pristine w 157k when purchased 161K now 83 300 D turbo 297K runs great. SOLD! 83 240D 4 spd manual- parted out then junked |
#14
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Use the lowest ohms scale (least sensitive) if you want to get a more accurate reading. If you pull the old plugs out, the best way to test them then is to power them up and watch them glow. If they are in the engine, the best way to test them is power them up individually with an ammeter in series and measure the current.
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85 300D turbo pristine w 157k when purchased 161K now 83 300 D turbo 297K runs great. SOLD! 83 240D 4 spd manual- parted out then junked |
#15
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Quote:
If the Start to glow in the center of the Heating Element that is also a bad Glow Plug eve if the Ohm reading is good. Look in the DIY section and find some way to Ream or other wise clean out the Carbon from the Glow Plug Holes.
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84 300D, 82 Volvo 244Gl Diesel |
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