I just put a new set of bosch glow plugs in my 79 300td making sure to ream also -- it had been having a really hard time starting even at 50F! It starts great now at 40F -- we'll see at 20s and lower soon..

I tested the old plugs with jumper cables and they seemed to light up just fine. I didn't check with the ohm meter, but if they light up good, doesn't that mean they work? I'm a little confused, maybe all it took was the little bit of reaming at each hole and that was enough to get it started better?

thanks for any insight --

maybe there was a wiring issue before- bad connection somewhere to one of the plugs that was 'fixed' when you put in the new plugs and re-attached the wires. so now the circuit works properly...?
which style of plugs does your car have? is it the series type? maybe one connection was breaking the circuit, which i believe then makes none of them work..

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1981 240D ... 265k
1977 240D ... 265k
1977 240D ... 250k

Yeah, need to know if the plugs are series or parallel.

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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

It is good to do those things...
but also... the FSM says in cold weather if you are having trouble starting to leave the key in the glow plug position for 45 seconds .... do not turn it off and back on ... just time it to 45 seconds and see if that helps.... if you check the FSM they have a chart showing how hot the glow plugs get at various seconds of being on... and the difference between the temp at the usual time the light goes off... compared to 45-60 seconds is really big...

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/diesel-discussion/10414-help-i-need-check-stretch.html

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/diesel-discussion/156207-photo-step-step-post-showing-w123-evaporator-removal-1983-240d-1982-300td.html?highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html

Yes, sorry I omitted that detail -- they are the pencil style...

again, mid 40s today and what WAS usually a really, really hard start, now was much easier with new plugs...

besides testing plugs with a ohm meter, is there anything to look for to tell if a plug is good or weak by jumping it and seeing how fast it glows?

I'm very happy it is starting better -- just curious..

thanks for your info

The color of the glow is relevant. Orange not so good. Bright red good.

__________________
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