Greetings all. I've checked Alldata and the Bently book and searched the archives here and can't identify which hose is which on my fuel filter setup. I want to run a can of diesel purge through the engine, and want to run it straight from the can. Symptom is shaking at idle in gear, neutral and reverse. (have new mounts). Aside from going to the shop and lubricating the tech with cash, can someone describe which lines are which and which ones to disconnect for a purge? Any other tips are greatly appreciated.

Try my web site where I illustrate this on a 1983 300SD - yours cannot be too different. The source line for the purge is the one coming from the small pre-filter. The return line the one that would otherwise return unused fuel from the by-pass hoses to the tank.

Go to: Cars - Technical - Motor - Diesel Purge

Should have mentioned that I saw your excellent site too. Sorry, but I'm just not seeing it. Does the fuel supply from the tank enter the filters from the top of the pre-filter through that 90 degree fitting held in place with a 10mm bolt?

Attach the Purge feed hose to the in line filter at its straight end (not the right angled one). Use a piece of clear vinyl tubing for the Purge feed hose. Purge enters your system from the Purge jar via this vinyl hose through the in line filter. Picture 3 of 4.

The black MB return hose is the one connected to the metal pipe in Picture 2 of 4. If you trace the left hand most bypass hose (should be cloth braided, connecting all the injectors, sometimes vinyl if the wrong hose was used) you will see it is connected to the top of the main filter whence it turns into a black hose. This is the return hose which connects to the metal pipe which goes back to the tank. Disconnect it from the metal pipe (Phillip screw on a band clamp). Place MB return hose in Purge jar.

The vinyl feed hose must remain submerged in the Purge jar to prevent air entering the system and stalling your engine. The return hose can just dangle in the jar above the Purge.

Not clear what you mean by "....fuel supply from the tank....". The fuel from the car's tank enters the pre-filter first then moves on to the main filter. By disconnecting this connection to the pre-filter and substituting the vinyl hose, your jar becomes the 'tank' in lieu of the car's tank.

Does that help?

Borrowed this pic from another post, but it shows what I think are the supply and bypass lines. Right?

http://strait.cncdsl.com/Braided.jpg

Many thanks.

Well, I'm not familiar with that engine, but ordinarily the only braided line would be the bypass. You should be able to trace it from there down to the return metal line to the tank.

Can't tell on the supply line but if you plug your Purge supply into the fuel pre-filter, that will do it.

I just took a look at mine, and there are no less than seven fuel lines attached to the silly thing. I think I remember something about a prefilter buried under the big bracket next to the main filter. You might want to take the main filter off and peek in there. That may help confirm which line is which. But based on that, I would say that the line with the banjo fitting on the top left of the bracket is the supply line. And based on having the braided line atteched to it, the large black one with the screw clamp on it is the return line.

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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
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