Hello, this is my first post, and the first Mercedes I have worked on. I didn't see anything like this when I was searching about how to fix it so here's what I did in case it might help someone else.

While I was putting things back together after adjusting valves and running a compression test, I broke the hard plastic tube that runs from the banjo bolt on the intake over to the boost protection valve. It broke right at the banjo bolt fitting so there was enough tube left, I thought I would just cut the broken part off of the bolt and put the plastic hose in some hot water and put it back on, but soon realized that tube can resist a crap load of heat, there was no amount of boiling water that would help me get that tube back on the bolt. After a series of trial and error I finally came up with this trick, maybe everyone with a Mercedes already knows this but these plastic tubes are new to me. I kept trying to heat the tube to soften it but, what really needed to happen was to heat the fitting, here's what I did

turn my soldering iron on high ~850F

cut the broken end of the tube off of the bolt
cut/shave the end of the tube flat with a razor blade

put the end of the iron in the open hole of the banjo bolt and let it sit for a while in a pan or something to get the bolt really hot

keeping the iron in the hole of the bolt push the tube onto the end of the fitting firmly and slowly, it helps to push against something that wont move, I pushed against the corner of a pan which was up against a wall

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I though I could do the same thing to My Oil Pressuer Gauge Tubing. 25+ years ago the Plastic must have had some give to it. but not any more. It was impossible.

In your case you have an easy fix. Get a Needle Nose Pliers and a Butane lighter. Heat up the Hose still left on the Banjo Fitting and when is just soft enough Pinch it with the Pliers and pull it off or pry it off with some Screwdrivers.

After it is off simply use a several inch section of Rubber Vacuum Hose over the Plastic Tubing and the barb on the Banjo Fitting.
If you tink the pressure might move it off shove about 2 inches of Rubber Hose over the Plastic tube.

If you want it to last longer use Silicone Vacuum Hose.

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84 300D, 82 Volvo 244Gl Diesel

I used the vacuum hose and then flexible copper tubing.

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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

What brand ?

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'84 300SD sold
124.128

The soldering station is one I ordered from MPJA, only fifty bucks and it's working really well so far, model on it is 15485-TL

Nice trick - thanks for posting.

I just replaced all of my tubing with new stuff so I didn't have the trouble you describe - though I can see that for those that don't want to go shopping for the bloody car yet again (!) it is nice to use what you've got.

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!