This cold spell forces us to address glow plug failures. It took me 3 hrs to change 3 glow plugs, damn they are hard to get to! Starts right up now in 15 degree weather, whereas I couldn't start my 83 300D in 35 degree weather before the change.

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85 300CD Signal Red/Tan sold
83 300D Manganese Brown 109K
97 E420 Midnight Blue 197K sold
98 BMW 328i Vert White 100K, sold
95 BMW 525i White 125K, sold
93 BMW 525iT Red 193K, sold
95 E320 Green Wagon 125K, sold
94 E320 White 127K, sold
85 300SD 156K Grey (Annie), sold
84 300D Lapis Blue 170K (Judy), sold
99 ML 320 Black (lease), 1998 C230 White (lease)
00 Honda S2000 Red (lease)
86 Mercedes 300E (sold)
84 Porsche 911 Red (sold), 1965 Porsche 911 White (sold)

LUCKY YOU! I have two left that are literally spinning in place. Hopfully the remover tool I ordered will get them out. Ya gotta love, and hate, the 606's and their long arse GPs.

BTW, water pumps fail when I bring these southern diesels up to NY winters. Odd, but sees to be true.

It sure does! doesn't it? See all the discussion about cold starting today

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"

If you have big hands, it's a royal pain, especially #1 and #5.

On two cars that I have purchased, including my current 300d, when I went to change the GPs I found that the #5 was older than the others. The last person who did the job either couldn't be bothered or gave up on the last one.

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22

This is why I constantly raise this topic during the WARM months.
* If you don't enjoy walking in the COLD.
* If you don't enjoy working outside in the COLD.
* If you don't enjoy being stranded in the COLD.

I strongly suggest replacing glow plugs at the first hint of cold starting issues during WARM weather.

Note: Several of my local customers with OM60x engines have experienced the seized/broken glow plug issue (cylinder head removal), and now elect to remove the glow plugs for testing, cleaning, lubrication, every year as routine maintenance.

.

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ASE Master Mechanic
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Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
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Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
2003 Volvo V70

https://www.boldegoist.com/

I took this advice about 5 years ago after moving to Wisconsin, and the 50 bucks in new glow plugs every year is a total no brainer if you are living up NOrth.

I do it on my UD diesel flatbed(best work truck ever) , and it started right up at -15 yesterday, with no block heater as that blew up last week. I did cheat and have a oil pan warmer on it though.


You are out like 1 hour of your time, and maybe 20 bucks in replacing "sort of functioning" glow plugs, but this is cheap, easy insurance. Love to all, TheKid

Okay, Guilty ! At least once a week for the last few months I keep telling my son " I need to buy some glow plugs and replace them before it gets too cold "( the current set is on their second winter ) As luck would have it I have been having to park the 300SD in front of a friends house until materilals are removed from my driveway. Well this morning it was 11 degrees without throwing in the noticeable wind chill factor. Now I thought this would not be a problem so I had the wife drop me of ( 2.2 miles away ) wearing my pajama bottoms, sandals and my over coat. She drove away and I tried to start the car ............. slugish etc.
Long story cut a little short. I climbed in my friends garage window and nicked his longest extension cord about 100' and plugged her in and waited. It took about 40 minutes for it to get warm enough but she coughed and started.
Now that was the longest 40 minutes ever. My feet were frozen as I drove back to my house. I am installing GPs tomorrow and will start plugging her in at night.
Thank God I installed a new battery last summer and did adjust the valves, just no glow plugs. Never again !

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92 500E Silver 66k
82 Porsche 911SC 84K
68 Cadillac ( Gone Now )
03 Suburban Z71 200K
85 300SD 217k From Original Owner ( Dad )

Wait until you decide to change glow plugs on a 350 SDL

__________________
Strelnik
Invest in America: Buy a Congressman!

1950 170SD
1951 Citroen 11BN
1953 Citroen 11BNF limo
1953 220a project
1959 180D
1960 190D
1960 Borgward Isabella TS 2dr
1983 240D daily driver
1983 380SL
1990 350SDL daily driver alt
3 x Citroen DS21M, down from 5
3 x Citroen 2CV, down from 6

Why did it take so long?

I can change #1 through #4 in less than 3 minutes each. #5 longer, may 10 minutes. The trick is have the wires easy to remove and use the correct tools.

I'll probably never have to change mine again since going to a manual glow plug relay because they don't get used much except from a dead cold start.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Because the 8mm nut the holds the wires on are tight and awkward and do not spin off. You need to wrench them out with a short wrench. You also need a deep 12mm socket to get it far enough in to rachet the glow plug out but there's not enough room to use a rachet so again you have to awkwardly wrench them out. I found the #5 the easiest to remove because there is room in the back to pivot a wrench.

Ratcheting combination wrench.

This and I always like to loosen up but not remove the nut on the glow plug, so I don't lose it. on concrete, it's easily found, but on gravel.......

That's because some knuckle head over tightened those 8 mm nuts. They should only be tight enough for an electrical connection such that they don't come loose from vibration, somewheres around 1 to 2 ft lbs. I eliminated th nuts altogether with quick disconnects. One yank on the wire with long nose pliers and it's off in a split second.

To get the glow plugs off (again they should not have been overtightened), Loosen them with a long box wrench first, then use 1/4 in ratchet and socket with universal and extension to get #1 through #4 off.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

On a 617 I pull the hard lines and on a 60x I pull the intake manifold. No sense busting knuckles and using strange tools. Just remove what blocks them. I can do 617s in less than 30 minutes and a 60x in about an hour.

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

Exactly. I have one that goes from 12 mm to 8 mm so it and my 17mm for removing the hard lines to give operating room was all that was needed. i think I completed it all in 2 hr. and I used a needle nose vise grip to hold the wires while taking them on and off.

I'll never try to do it with the hard lines on again.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.