Converting glow plugs?---loop to pencil style
 

I've searched, but found nothing helpful....
On a '79 CD with loop style plugs, what is required to change over to pencil plugs? Can a controller and harness from a later model be spliced into the original system? Where?

M S Fowler,

I converted my old 190D to pencil (parallel) GP and it started much quicker. I made bushings out of the loop GP in a lathe and screwed the pencil GP `into the bushing an dinto the head. Hardest part was getting out the porceline.

I just ran wires with crimp on terminals from one GP to the next, replaced the resistance wire in the dash indicator with a piece of solid copper wire and connected the in and out wires to the resistance box to the same terminal (thus removing the resistor box from the circuit).

I have heard that replacement parallel GP kits with larger GP threads are available which would make the conversion much easier. However, I don't know where they are available. Maybe soneone else in the forum knows.

P E H

Thanks,
For those of us w/o lathe access ( or skill, for that matter), couldn't bushings be made by tapping thru the center of a bolt that was the same thread, and length as the loop style plugs? Is there any special consideration given to the type of metal used to make the bushing?

i have a set
 

that i bough t from jc whitney years ago. i cov=nverted my 220d and the plugs didnt last very long. i dont recommend changing them over. in fact i will give the set i have to anybody... but i still dont recommend it.

they have
 

a bigger base to fit the old style heads and wires to convert over. they used to cost about $40 fifteen years ago. dont know if jc whitney still offers them.

There is a conversion you can buy from parts places online. It is made by Bosch, and costs about $100, and the part number is "0 250 201 955". It comes with new pencil style glow plugs that fit correctly, a new pre-glow relay, and a wiring harness. The kit is meant for a 4-cylinder, but with one more glow plug and a 25amp relay, it will work for a 5-cylinder. I installed it on my '78 300D and it worked great!
By the way, I bought it from "thepartsbin.com." It only comes up when you look up that part number above.

when
 

i did the conversion it was with a manual gorilla knob.

maybe i just glowed too long and burned them out.

M S,

A bolt might work but you would still need a lathe to cut the tapers to make air tight seals between the bolt and the head and the GP and the bolt. You also have to tap threads in the bolt to fit the GP.

Looks like your best solution is to buy the Bosch conversion kit TBAKPhi22 mentioned if it is still available.

P E H

try this link: http://www.peachparts.com/shopforum/mercedes-parts-reference-library/178765-f1101-88322-kit-converting-loop-series-gp-hotter-pencil-parallel-system.html

I bought it from them for my 240D and it works great. I'll never go back to loop plugs again. Nothing but good from this kit. Free shipping too ;)

Add this to the catalog of information on this topic.

Replaced the '78 "loop style" glow plugs the other day with five new Bosch M19 thread "pencil style" glow plugs.

I used 10 gauge wire and crimp on ring terminals for the circuitry. I decided i would try: wire from firewall to #5 --> series wiring up to #1 --> remove the ground strap for my configuration.

I hasn't been tremendously cold here over the past weekend but i did get to test 'em with a low 40's start the other morning and "El Torro" definitely fired up better than ever.

So, i guess I'll stick with that wiring configuration for now. until some problem arises or someone wants to chime in with a definitely better way to do it.

I highly recommend this conversion if there is anyone out there still running loop styles.

though, I'm probably the last one :eek:

Wired up my pencil conversion on the 77 300d the same way. Worked fine for years. One of the best things to do to an engine with the old loop style plugs.

Same here, just did it on my '79 300D. Starts on the first crank after 15 seconds or so of glow on a 35ish degree pre-dawn morning. Big improvement over the old style.

I also strongly recommend this conversion. Somewhere in my shop, I still have a briefly used pencil plug and wiring kit from my old '73 220D (OM615) I'd let go for cheap.

I installed 18MM pencil style glow plugs in my 76 240D.
I used a 82 300D pre glow relay incl. wiring harness.
Retained the gorilla knob and replaced the salt shaker with a indicator light.
Works great.

If your Original Glow Plug Relay works with the set-up all you need to do is replace the Glow Plugs, make sure an 80 amp Fues is in the Fuse Holder, get rid of the Ground Strap from the old system that you do not need, install the Adapter Plugs (80035 I think is the part number) and make the Jumper wires.