Thanks as well for all the info above. Our '86 purchased last november, never liked cold weather. During this last summer, it started fine, so I forgot about it. However, now that it's dipped in the cool temps again, lots of cranking to get it to start. My first attempt at doing the glow plugs, worked quite well.

The first two, using a universal joint, and a 1/4" drive socket and extensions, was able to keep the fuel lines attached. Number 3, however, took a few beer to change out. Number 4 was a piece of cake, 5 proved difficult, had to disassemble the upper throttle linkage. Number 6 was easy too.

I replaced all with the -39 plugs, which are 11v versus the 11.5 that were in there. Knowing that a few were still good, wanted all to be the same. Starts right up now, wished I had done it sooner.

__________________
1986 Mercedes 300 SDL
1975 Mercedes 450 SL
1985 Porsche 911
1980 Porsche 924 Turbo
1981 Porsche 924 Turbo
1971 Jeep CJ5 Renegade II
1995 Jeep Wrangler lifted
2001 Ford F350 Diesel to find more junk
2004 Car Trailer, to haul junk that the truck finds.
1993 Damon Challenger, diesel pusher RV
1958 Pam - Loving wife that puts up with the above!

So how bad was #3? My #3 & #4 are the only two out. I am thinking of trying to change them without removing the intake. Looks like #3 would be easy with the CC actuator out of the way.

__________________
Brian
87 300Dturbo 180K #14 head still running R-12 SOLD 12/2017
02 F350 Powerstroke 180K
05 Chevy Express 1 ton w/Royal Utility box 120K
08 Infiniti FX-35 40K
15 Golf Sportwagen TDI 35K
10 Sprinter 3500 chassis with a Class A Winnebago on it. 56K

The plugs were only 2 years old, after the initial 'snap', they unscrewed by hand. Anyway, the #3 would be better accessible with that removed, but, I worked around it. The 1/4" drive stuff worked great. I think I accessed the plug from the right side; I don't have the car right now to verify it. 12mm deep socket on plugs, after 10mm short socket to remove wire nut. BTW, the 'captured' nut wasn't captured on that plug, ugh. Added a few tense moments as I had to search for it. Putting it back on wasn't too bad.

__________________
1986 Mercedes 300 SDL
1975 Mercedes 450 SL
1985 Porsche 911
1980 Porsche 924 Turbo
1981 Porsche 924 Turbo
1971 Jeep CJ5 Renegade II
1995 Jeep Wrangler lifted
2001 Ford F350 Diesel to find more junk
2004 Car Trailer, to haul junk that the truck finds.
1993 Damon Challenger, diesel pusher RV
1958 Pam - Loving wife that puts up with the above!

For anyone that still needs this fix for their W123, check out the DIY tech article from our site below!

Glow Plug Replacement