yuril

All fuel leak threads seem to be about the lines around the fuel filter, but my case is different, here are the symptoms:
1. Can start and drive at slow speed, but no acceleration (fuel leaking from below the engine -- geez, good that it's not gasoline...)
2. Covers off, turning the key to the second click for a second, pumps started, fuel leaking out of bell housing cover (!)
3. No visible leaks on top of the engine, including high pressure fittings
Your expertise is really appreciated, thanks!

kajtek1

From what I recall that sedan has solid fuel lines coming from the tank, when they have rubber hoses connected behind PS pump.
That engine has very bad access to everything, but you will have to dig it.
Use paper towels to pinpoint the leak.

GoodByeHonda

I'm guessing return line O-Ring on top of one of the injectors

yuril

Hi Krzysztof,
Thanks for your reply!
I have just found the smoking gun...of course, it is the return line plastic clip on cylinder #6.
Maybe needs a new o-ring after I took it off a couple times last year.
Yuri

yuril

You got it right, thanks so much for helping!

Bern6389

is it the oring on the injector for the fuel return? If so I have extras!

j-dawg

Bought a fairly high mileage ML350 yesterday, 244k on 3.0L diesel. On the way home, excessive smoke from under vehicle. Pull over, check underneath, huge puddle of fuel. Open hood, white smoke. Further inspection I removed the air filter on drivers side and the injector return line on 2 injectors where leaking. Is it just me or does this clamp system on the returns seem like the cheapest system for a quality vehicle?

GoodByeHonda

I'm my experience, the seal works properly if you utilize OEM MB seal. I tried using the ones from the oil cooler seal kit that came in the elring set and those where slightly larger in size which was clear when attempting to slide the return line ring down onto the injector. I.e. I got no click and wasn't sure if the ring was locked in place

kajtek1

When plastic fuel connectors don't have infinite life expectancy, I think this is more issue of "mechanics" who sledgehammer the fitting without reading how the clips work.

B34chBum

All good points ^^++

The previous generations 642 and the 5 cylinder in the earlier sprinters, they had metal fittings. I would imagine they didn't have as much trouble.
Especially if you get black death soot on them it's tricky to remove the clip because it can get clogged and not want to move. You have to clean very carefully with acetone and brush to free them up in that case.

I found in assembly it was helpful to lube the oring and clip's sliding ring with silicone grease, as it usually helps with orings anyway.
I think it's a pesky system all around - designed to support parts sales.

Oh, and you have to remove both air cleaner and the foam engine covers, to get a visual on any leaks from these.
Especially for the guy who hasn't had it all apart before, is the biggest hindrance.
Accessibility is worst for the R-Class, which of course is what I have (slaps head)!
Sometimes wish they had stretched the hood out like on an E-Class! But I'm sure it would get dinged up even more!!!

j-dawg

Was the orings. Obviously the the wrong ones installed. Bought some from the dealer and problem solved