My 85's with pencil type glowplugs start a lot better in the cold than the 77 with loop plugs. Since this is the only significant difference I can detect, I am wondering if I convert the 77 to pencil type plugs, it will start better in the cold (below about 8 degrees). What does everyone think? Anyone done the conversion and noticed better cold starts? Or is the difference so subtle as to be not worth the work? Is the difference just a matter of not waiting as long to glow or is it a better start? Can anyone give a theoretical explanation of the advantages of the pencil plugs?

__________________
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

Conversion from loop plugs (where less than half of the heat produced by the circuit goes into the prechamber) to pencil plugs (where 80-90+% of the heat is concentrated in the prechamber) WILL improve cold weather starting by almost 10 deg F. Changing to a full synthetic oil (likr Mobil 1) will also improve things about another 10 deg. F. but I don't know if these two different results are entirely additive. I have only tried the oil change myself (none of my cars have series/loop plugs).

I know of many people that have done the glow plug conversion and they all report vastly improved cold weather starting - changing it from a constant challange with every start to ALMOST fun, until temps get below zero (F).

Marshall

Thanks Marshall. Just the info I needed. I did the switch to synthetic and it definitely improved cold starts. I put in the heavy duty turbo starter and that also improved starting rpm's cold and hot. I'll put the plug conversion on my list of things to do.

__________________
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

Kerry, Bosch makes a conversion kit that includes the pencil type GP's that fit into the larger hole of the loop type as well as the relay that will keep the GP's glowing up to 3 minutes after starting. I upgraded my relay to this and the cold start improvement is great.

__________________
Democracy dies in darkness, you have to kick at the darkness till it bleeds daylight

One advantage of the pencil type GP over the loop style is that it does not require external dropping resistors (the connecting zig zag wire is resistance wire) so all the electrical current is concentrated at the GP, not having some wasted outside the engine in those wires (if you ever touched one when starting you know what I mean!)
I believe pencil GP's have lower mass, so they heat quicker also.
Dieseldiehard

I bid on a conversion kit on ebay since Fastlane doesn't have one. The seller contacted me and told me that in reading the instructions, they state that installation in a 77 300d requires one more relay in addition to the one that comes in the kit. Can someone who has done the conversion on a 5 cylinder comment on this? Are two relays required? If so, why? I don't understand why one relay would be adequate in a 240d but 2 necessary in a 300d?

__________________
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

I did the conversion on my 71 220D this past weekend. The car has never started so easily! Of course, this is also due to a long overdue valve adjustment, but I am amazed at the difference.

The 220D is a four cylinder, so I didn't have worry about the extra cylinder stuff. According to the instructions for the 5 cylinder, you will need (obviously) an additional glow plug and a bit more work. I didn't see anything about need an additional relay. I would forget about the kit on eBay and contact Rusty at mbz.org. That's where I got my kit, and no doubt they will be able to sell you whatever else you need to complete the job.

Eric