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Old 11-19-2004, 08:33 AM
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Location: Kittrell, NC
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Glow plug change on '82 300sd

Want to change out my glow plugs on my 1982 300sd. This would be a first time for me doing this. Any suggestions? Should I use Bosch or Beru? Someone said Bosch had a plastic collar they didn't like. I don't think on this one I have to remove the manifold. They are on the side of the manifold. Looks accessible. Please give feedback before a newby screws something up. I just want to make sure I do it right the first time.

Still have that stinking clunking noise when I pull up and put the car in park. It is worse in park than in drive. Just had the valves adjusted. Could the transmission mount and engine mounts or engine dampeners if bad really be sending that much vibration all the way down underneath the car. Sounds like the clunking is coming from underneath or towards the rear of the car. I really want to get this issue fixed.
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Old 11-19-2004, 08:50 AM
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Join Date: Oct 2004
Location: Deltona, Florida
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Are they bad?

Why would you just decide to change them?
Is the car not starting right, does it crank for a long time before it finally starts?

Follow the plugs wiring harness back to a black connector box on top of the wheel well.
Disconnect connector, you will see they are numbered 1 to 5.
Set your OHM meter to 200k or 20k it really doesn't matter.
Put the red probe in a numbered port and the black to ground.
Anything showing infinite (1.X) is bad.
You can also check them against each other.
what I mean is if the highest reading you get is say 75 - 100 and one of the plugs shows say 20 then I would replace the one that says 20 because it's on its way out.

I just replaced 3 on my '84 300SD and didn't have any problems other than accessability. But you do have to be careful not to break them in the block.

A little penetrating oil wouldn't hurt and a light tap to break any scale loose.
Did I say light tap? Oh yeah yes I did.

Overall it's a pretty easy job.

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Old 11-19-2004, 08:59 AM
Benster Tom
Posts: n/a
Danny would this be the same for a W126 on the glow plugs as far as checking them out. Faslane is running a good price on glow plugs right now. I'm not sure what brand they're selling.
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Old 11-19-2004, 09:58 AM
Old Deis
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For the most part the Bosch glow plugs are best. Get them on fastlane or at Autozone. I tried Beru twice, both times they blew out within a season.
Most of us have found there is no value in replacing if they have not failed. Only replace the ones that have failed. Seems that some will operate for years and years, put in nice new and that may fail within a few months.
Just pull the connections and check each glow plug with an ohmeter. There are specific ohmages, but if the thing is not working at all there will be a zero reading on your meter. Takes a bit to check them all. I am always impressed with how handy the access is to them, but well worth the effort.
BTW, if you are not sure of a reading on any one, pull it and clamp the plug into a vise, use jumpers and ground the vise and touch the end with 12v. If it works will get red hot immediatly. If if don' t will stay cold.
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Old 11-19-2004, 10:03 AM
Benster Tom
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But basically when your testing your glow plugs, your checking them at the black box on top of the drivers side tire well, known as the "fuse box"?
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Old 11-19-2004, 12:16 PM
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Join Date: Sep 2004
Location: Kittrell, NC
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car has been hard to start on cool mornings

Just had the valves adjusted. It has gotten down a few nights into the upper 20's and low 30's and the car would not start the next morning. When the block heater was plugged up, it started no problem, but when not plugged up, the car would not start.
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Old 11-19-2004, 12:30 PM
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Join Date: Dec 2002
Location: RI shore
Posts: 2,937
you check the glowplugs by disconnecting the plug from the glowplug harness to the glow plug relay. It's behind the left headlight and also near the A/C receiver/dryer. Check resistance in ohms from each plug spade to engine block. Less than 1 ohm is OK, otherwise not. It's possible but unlikely that the extra resistance is in the harness. Also, you having 4 between .3 and .5 ohm and then one at .8 or .9 is marginal.
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.
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