My brother-in-law and I replaced the loop glow plugs in my 1978 300D yesterday, thought I'd share the experience.

Peach parts did not have the adapter plugs when I went to order, so I ended up getting a "kit" from another site. Just the plugs, a fuse and some premade wires.

For several days before, I sprayed some WD-40 or liquid wrench at the threads, hoping this would help free them up. I drove around for a while till the engine was at operating temp, then parked it and started work

I decided not to remove the injector fuel lines, figured I could work around them. Turned out to be the right call.

Used a 7mm wrench to remove the little nuts that hold the wires on. Removed all the wires and insulators. Then used a 21mm wrench to remove the glow plugs. They came out pretty easy, it was just very very time consuming as there was not a lot of room to turn the wrench between the injector hard lines

The loop plugs were very clean! Just a little blackened, otherwise they looked almost new. My brother in law is a VW diesel mechanic and he was shocked both by how easy the job was and how clean the plugs were. One of the loop filaments looked a little thinned and almost twisted, which may explain why one cylinder was always "late" when doing a cold start.

Since there was zero carbon or anything on the plugs I did not ream the plug holes.

Sprayed the new plugs with anti-sieze, threaded in by hand, then tightened with wrench. Put the new wires on, put nuts on over them finger tight, then gently tightened with wrench. I did not put the old insulators from the loop plugs since they are not needed for this set up; you want the wires together on the end of the glow plug. I connected the "power" wire that comes from the firewall but did NOT reconnect the ground wire at the other end of the chain of glow plugs.

Tried it out, wow, HUGE difference in starting. With the loops it would be three glow plug cycles and about 5 seconds of cranking while the "late" cylinder catches up. With the new plugs it's one cycle and it fires immediatly.

Anybody with the old plug system should do this conversion ASAP. It takes an afternoon, and two wrenches, plus whatever you buy the plugs for. I paid a bit of a premium, but then again I don't have to monkey with making home made wires. The job can be done with two wrenches, as long as you are careful about positioning the wrench and not banging up the metal injector lines

One thing I did notice is that for the first ten seconds or so of idling from a cold start there is an almost unnoticeable "miss" that disappears as soon as the temp needle starts moving. That one slightly thinned loop plug may be a symptom of something else rather than a cause.

This is indeed a very quick easy job and a big upgrade. I've been running pencil plugs in my '79 for two years now. Did mine after the #5 cylinder loop plug burnt in half, disabling the entire glow system and blowing the 80A fuse.

I made my own wires; simple, really. Use 10 gauge wire, anything higher is too thin. Then just crimp on some round ends and you're set.

These are good instructions:
Mercedes Diesel Glow Plug Repair

Glad you've shared your experience.

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1979 300D 040 Black on Black - 1985 300D Maaco job (sadly sprayed over 199 Black Pearl Metallic) on Palamino

http://i.imgur.com/LslW733.jpg

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Hard to beat that upgrade on an older MB. It's also hard to imagine the difference it makes until you experience it.

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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

I did it on the 75 300D I had many years ago so I knew it would be a major upgrade, but you don't really realize it till you've experienced it.

I kept the loop plugs and other than the one they look like new. Given that it took a while to track down adapter plugs, how hard is it to remove the loop innards from the loop plugs, remove pencil innards from some standard pencil plugs and swap them in?

Or drill out the guts and make adapters

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

The 18mm fast glow plugs are readily available from many places. Search Google for "Bosch 80035" and you'll get lots of options.

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1979 300D 040 Black on Black - 1985 300D Maaco job (sadly sprayed over 199 Black Pearl Metallic) on Palamino

http://i.imgur.com/LslW733.jpg

The Baja Arizona Oil Burners Send a message if you'd like to join the fun
Left to Right - UberWasser, Iridium, Stuttgart-->Seattle,, mannys9130

Visit the W123 page on iFixit for over 70 helpful DIY guides!

I hope you didn't get the plugs from the site that shall not be mentioned, because they are monark brand which aren't to well looked upon....

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I did exactly that, but at the time I needed to buy the only ones not sold out were The Source of Mercedes, and the Giant of Diesel if you get my drift

Apparently I picked the wrong week to buy.

Just Google Bosch 80035, you can still get them on amazon.....Google monark glow plugs and look at the horrible reviews.....I would rather dump wmo in my tank then to put them in my car...

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My Google turns up a handful of bad reviews for Monark glow plugs; nearly as many reviewers state that they haven't had any problems with them, and not too many of the comments are more recent than 3 years ago. My own experience puts me in the latter group. I bought four Monarks last year for my '83, and they still work fine.

I think that if you have an opinion, then it's OK to state your opinion-but if you have no firsthand experience to convey, then you do nobody any favors by overstating your opinion.

Perhaps it's because I have a low-mileage engine and it doesn't get very cold here, but the upgrade on my '79 really didn't make much difference. I do get faster starts with the pencil plugs, but I never had starting problems to begin with. I went with the 80035's because they were only a couple of bucks more than straight replacements. If the loop plugs are in good shape, and you have clean pre-chambers, then they will certainly get the car going. They just take a minute longer.

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'79 240D

My plugs were Bosch's. I noticed a huge difference in both cars that I did the swap on, and both had healthy engines

I think sharing information is what the Forums are about; even if it is saying this is what others have said.
I the case of cooljjay He gave His opinion and said see for yourself.

In installed Monark Glow Plugs in My Car and one died about 1.5 Years later. That is in Southern California weather, Glow Plug Holes Reamed and low mileage driving on Injectors rebuilt 2 years before.

It was a sneaky one. It ohmed out OK but as you see in the pic it gets hottest in the middle of the Element.
Also after I took that pic and it cooled off I Ohmed it again and it failed and when I tested it on the Battery again it died!

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

I agree, and seeing for myself caused me to conclude that his argument was very weak. He has his right to his opinion, and I have my right to assert my opinion that his opinion is based on very little research and no first hand experience. Since there is very little hard data to help us decide about many of the things that are discussed here, a variety of opinion and anecdote is about as good as we can get. I did see for myself, and I shared my results. I'll reiterate them: Google turns up few reviews on Monark plugs. Not all of them, and not even an overwhelming majority, are negative. Few of them are more recent than 2010, and that fact is worth considering in a rapidly changing world. Judging from the sample size and age of the reports, I found nothing that would influence my own decisions.

I recently read somewhere (and regretfully, I can't provide the link), that Monark did experience manufacturing problems in the 2008-2009 time frame, and they have since corrected their quality issues. I don't know if that is true.

While opinion is perhaps the best information available, much of the opinion shared here and elsewhere is regurgitation, and much of that is not quality information. Everyone should understand that and dig deeper.

Your own account of your experience doesn't indicate when it happened either. I'm not implying that your experience is worthless to me, but it carries nowhere near the weight of controlled test results. Unfortunately, there seem to be no controlled test result. BTW, I had the same experience once with a Bosch plug. Based on that, I wouldn't condemn all Bosch plugs. Would you?

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'79 240D

I have had several failures of Bosch loop GPs in my 220D and no longer use them. I found a bunch of Beru NOS GPs and they have been better than Bosch for me. My car runs hot and and some internal part of the Bosch loop plugs was failing. The same has not happened with Beru. Again, this is only for Bosch loop GPs, which were made in India.

I have recently installed Bosch pencil GPs in my w124 (made in France, by the way), and they seem to work great.

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).

Oh, and I know I am in the minority, but I really like using loop GPs in my 220D. I wouldn't own that car if speed of transportation was vitally important to me.

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).