I have been having trouble getting the SD started in the morning over the last couple of days. Yesterday I noticed the glow plug light wasn't coming on all the time and decided to replace them. This morning the car wouldn't start so my dad gave me a ride to work and told me he would look at it.

Well even though with a meter all the glow plugs tested ok he found something very interesting. When you stick a good glow plug on a battery the tip will glow red in a couple of seconds. Well he stuck all 5 of the old glow plugs on a battery and only ONE glowed red. The other 4 only got a little warm.

So the light was coming on when only one glow plug was actually glowing!

The point is if you are having trouble starting just spin a new set of glow plugs in. Now the car starts without much trouble. The $50 that a new set cost was worth every penny, I need the car to start.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Well the light became "sporadic" and didn't come on every time...

After all its measuring a current drop...so that one glow plug SOMETIMES will drop a lot more (cold) than when it is hot.

When the 617 gets down to one glow plug...its hard to start. And yes, the light stops working at that point...or atleast starts not ALWAYS coming on

My light quit working altogether, but the car started fine. As it turned out, my #1 glowplug was bad...very easy to check. I replaced it with a new one (crappy Autolite for now until my new set of Bosch arrive) and everything is cool...

Lifted from MB Service Manual doc 15-705,
click here or on image for complete PDF file:

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-Ken Harris
1984 Mercedes 300SD
2001 VW Passat 1.8T
2004 Harley Davidson FLHRSI
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Der Dieselfanatiker

Did you ream the holes when you put the new ones in?

Any special tools required?

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Current Stable:
1994 S500 v140, 210k miles, white with grey.

Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold (rumor has it, that it has 750k miles on it now)
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 "300E" Amg Hammer 88k mi sold (it was really a 200, not even an E (124.020)
1992 500E 156k mi sold
etc.

I didn't ream the holes as they were pretty clean...

__________________
-Ken Harris
1984 Mercedes 300SD
2001 VW Passat 1.8T
2004 Harley Davidson FLHRSI
-----------------------------
Der Dieselfanatiker

Would you recommend doing so?

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Current Stable:
1994 S500 v140, 210k miles, white with grey.

Former Mercedes in the Stable:
1983 300CD Turbo diesel 515k mi sold (rumor has it, that it has 750k miles on it now)
1984 300CD Turbo Diesel 150 k mi sold
1982 300D Turbo Diesel 225 sold
1987 300D Turbo Diesel 255k mi sold
1988 300 CE AMG Hammer 15k mi sold
1986 "300E" Amg Hammer 88k mi sold (it was really a 200, not even an E (124.020)
1992 500E 156k mi sold
etc.

I didn't ream the holes and never have. On a 606 I would, but not on the older engines. Carbon really shouldn't be a problem on these unless you idle them around a lot.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

They make a special reamer that will fit on a socket wrench but if I remember correctly its a tad expensive. I read on here that a drill bit of the same size works and thats what I did. Crank it for a second or two to blast that carbon out of the prechamber. I probably won't do it the next time I need plugs done. I only did it this time because it was my first change and not a lot of carbon came out.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo

A couple of months ago I put in a new battery then a few weeks later the glow plug indicator stopped coming on but it continued to start. Roughly a month later I hit the horn and it sounded like my '62 bug, whimpy. Then I lost my instrument panel lights but it continued to start for about a week. Now it wont start. I need help, any suggestions?

Your alternator or voltage regulator has failed. Search the forum for those topics.

I must ask, why did you continue to drive it knowing it had a significant electrical problem?

Wow i'm suprized i figured even if 1 was down it wouldn't start on a 4 cylinder vw engine u can tell right off it thumps like crazy the 5 and 6 cylinders smooths out the rough cylinders they're a bit tricker to tell.

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2004 Infiniti G35 3.5L 6mt Coupe 73K miles 25.6mpg ytd
2001 Green Audi TT 225 AWD Roadster 71K 6sp 30.9mpg >>STOLEN<<
1982 300D Turbo 231K 120hp? 28.1mpg YTD

I use a battery charger to test the plugs to see if they glow. I never knew about using a voltage meter, so I figured the best way to test them was to pop them out the hook up a charger to them to see if they glow.

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My 300SD does not light the glow plugs indicator, does it mean I should change glow plugs because I am down to one?

It starts fine but now at around 12-15F it got harder indeed, few more cranks and rough few seconds after starts, then like a dream

http://www.peachparts.com/shopforum/vbpgimage.php?do=full&p=3664&d=1229373678


BTW, BOSCH or BERU?

Check your fuse in the relay and make sure the plugs are getting 12 volts when in the glow position before changing plugs, but it probably means the plugs are bad.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

The light in my SD was taking a second or two to light up after I turned the key to the pre-glow position. I checked my plugs and had one out, now that I have replaced the plug it lights up immediately.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine