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Thanks. So "How do you bleed the fuel system after replacing the fuel filter on a 2012 ML350 Bluetec?" I have an F450 that says cycle the ignition on 10 times before starting and a John Deere tractor that has a plunger and a bleeder petcock. But no idea how to do a Mercedes.
When you install the new fuel filter, you will see a little cap on the top held on by a cotter pin. This cap closes off the bleeder port. Remove the cotter pin, remove the cap, and have a quart container at hand to direct the overflow into once the filter fills with diesel. I use my brake bleeder container which has a silicon hose that I attached to the bleeder port. Have a friend turn on the ignition and be ready to turn it off quickly as soon as fuel starts to spurt out of the filter. Takes about 5 seconds as I recall.
I have never bled the fuel system. Cycle the key twice and it usually fires immediately after that. My understanding was that port was to drain off excess water should it make it into the system.
I have never bled mine either. I just cycle the key as a previous poster mentioned. There are two fuel pumps and the filter is usually full enough to start and run the engine, then it fills up the rest of the way.
Remember these are like mini oil filters, so you can fill them up with a bunch of diesel before installing them if you really want to. On the older diesels (1986 300SDL for example) I used to fill them with Diesel Purge so the engine would get 1/2 quart or so of Diesel Purge running through it when the engine started. Cleaned out the engine really nicely, but probably isn't useful on the newer diesels like the W164
I'd just cycle the key a few times, then start right up.
I didn't bleed the first filter I installed - and like you folks I didn't have a problem. And then I read a thread here about someone who did have a problem after not bleeding a filter, so I did bleed the second and third filter I've installed.
If I thought it through, I'm not really sure how you could end up with air in your injector lines (I recall this was the concer) that would last for any significant amount of time - it seems like as soon as the new filter fills up there would be plenty of fuel and pressure to push out any air that had crept it's way in there. And if you ever ran out of fuel, you would seemingly have the same problem. The fuel pump starts going as soon as the key is in the on position, ask me how I know...
That post is not helpful for guys with the 2013-2014 model years. There is a large protrusion that butts out of the turbo inlet pipe, directly above the fuel filter assy. making it literally impossible to remove. It is a very involved job that requires removal of the engine front cover, and complete removal of the turbocharger main inlet piping. Not a job for rookie mechanics as there are special procedures for pipe removal, Mercedes rates job at 4.6 hours book time for fuel filter replacement. Effectively making It a $500+ job (from Mercedes)
My sympathies for the owners of 2013 - 2014 you mentioned above!
(it almost looks like the "protrusion" stub has no function and could be removed & aluminum blank be welded in it's place?)
Guys, why not just replace those fuel filter factory hose clamps with these and you will have much easier time when changing the fuel filter next time.
Also, if you put small amount of graphite type never-seize on the hose fittings they will come off much easier next time.
well, I did my fuel filter and air filter change the other day, but after putting everything back, there is a one wire that I can't find where to connect to
Can anyone help?
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