There's no real trick to it. If you pull hard on the line it will act a bit like those Chinese finger traps, where the line cinches down tight just because you're stretching it. I found that using needle nose pliers to pull the lines off close to their end worked well.

Kevin

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'85 300SD

Thanks for the tips. I replaced the lines on my 85 300SD. The injector closest to the firewall has only one line going to it as opposed to the others that all have 2. The injector appears to be leaking. Is the hole where the second line would ordinarily be plugged or screwed? The leak may be coming from that location or below. Can the injector be tightened?

That injector closest to the firewall (injector #5) is supposed to have an end plug on the other side where are it looks like a return line could be fitted. You replaced that plug as well right?

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1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver

#5 should have something like this on the end. What you can barely see is that there is a plug in the end of the tube. Fastlane has them.

D1040-103301 - Diesel Injector Plug

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'84 300CD Turbo 132k (Anthracite Grey) - WVO - My daily driver - Recently named coo-coo-coupe by my daughter.
'84 300D Turbo 240k (Anthracite Grey) - Garage Queen
'83 300D Turbo 220k (Orient Red) - WVO - Wifes daily driver

I'm not a certified mechanic, but I did stay at a HolidayInn Express last night.

I recently had a fuel leak problem...after much frustration (changing rubber return line, changing hard line to fuel pump), the leak turned out to be coming from the base of one of the little nipples, or hose barbs (to which the rubber return lines attach). These nipples can't be tightened..they are pressed in. I fixed it by getting a used injector from a bone yard, and swapping the "inards".

Warning: The rubber return lines (with braided exterior) are hard to pull off...I probably caused the leaky nipple by pulling too hard. Be very carefull not to bend/damage/stress the nipple when pulling these. If you are just going to replace, just cut the outer braided part at the nipple and it will come off easier. If you are temporarily removing these hoses, rather than just PULLING them off, try PUSHING the edge of the hose up with a screw driver at the same time. When you just pull these hoses, the exterior braided portion acts like those woven straw chinese joke shop finger pullers...they push on easy, but tighten when you try to pull off. If you push the edges of the return lines off with a screw driver to prevent the braided part from tightening, the lines come off rather easily.

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)

I just used a razor along the side of the nipple so that it wouldn't scratch and cut them off.

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Adam Lumsden
(83) 300D
Vice-President of the MBCA International Stars Section

Does the diesel injector plug just screw in?

That plug does not go directly into the nipple. You put about a 2 inch section of return hose on the nipple and then push the plug into the other end.

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References