For the past month in Northern California my otherwise reliable 82 300 SD has been either a pain to start or would not start. I changed the glowplugs and tested as I removed each gp . . . two were burned out and would not glow. This morning was 28 degrees, a good test . . . Car fired almost immediately! Back to normal and to think just two plugs created this condition! I did the job just before Thanksgiving dinner, now I am very thankful! Love the simplicity of my diesel!

That sounds about right. Mine will start and run rough with one bad plug, but it's a PITA to start with two bad plugs. With two bad plugs the indicator light should fail to come on.

Might as well step up and spend the other 30 bucks now... Birds of a feather type thing...

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64 European Coupe Brilliant Silver with Red interior 4 Speed Sunroof
87 TDT 286k
87 SDL 195k
83 SD 202k
83 SD 201k
83 D 286k
02 R1150RT 32K
00 122HP FLSTF
07 KTM 250SX

"Danger takes many forms"

Anticipating you will be with us for some time and back to ask questions and contribute as well, let me ask you to complete the "Signature" part of your profile so that your MBz's basic statistics are visible in ALL of your POSTS... something similar to what you see below on this POST!
Regards,

Having just done this myself, I strongly suggest always replacing all the glow plugs at the same time.

I had 2, 3, and 4 out. I had a used, but still functional, one left over from the last change, so I switched #2 with the used one and put new ones in 3 and 4.

3 days later, 1,2, and 5 were toast.
So I replaced those and now have all 5 new ones doing the job nicely.
I figured I'd save about $30. Nope.

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85' 300D No inspection, No registration fees, Cheap insurance
"If my calculations are correct, when this baby hits 88 miles per hour, you're going to see some serious %$&^."

Yes, I had replaced all five at time of removal and testing, it would be foolish and a waste of time to just replace the burned out gp's

Replaced all of my glow plugs about a month ago......posted a thread here, commenting on the marked improvement in start/idle when engine is cold....

I, also, think it to be a waste of time to test and replace them individually!!

SB

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Diesels:
'85 300D, "Max, Blue Benz", 155K, 27.0 MPG
'84 190D 2.2, "Eva, Brown Benz", 142K, 40.2 MPG
'77 240D (parts car)
'67 Eicher ES 202 Tractor "Otto" (2cyl, Air Cooled, 30HP)
Gassers:
'94 Ford F-150, "Henry", 170K (300 Six) 17.5 MPG
'85 190E 2.3, 148K....Parts Car
'58 Dodge W300M Powerwagon (Flat Fenders) Less than 10 MPG

Yes its best to do them as a set. When one or two have failed the others might not be far behind. Better use of your time to do the job one time.

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1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair