Please help me troubleshoot this (diesel) leak! (OM642)

[MrGreedy]

Legend. What an effort but well worth it for everyone in the forum who looks at just getting that rigid aluminium turbo pipe off!
I will find this useful and I might tackle some smaller jobs as a result before the big oil cooler mission in the spring. I'm just thankful I've got a decent selection of sockets, UJs, extenders, ratches etc

I've come back to this thread having spent 80 minutes rooting through WIS to try and find some sensible instructions on what needs to come off.
And the result is.... I don't think WIS covers replacement of this "low-pressure fuel hose", which is the exact name of it.

I can find various references to this exact part for our cars in WIS.
How not to damage it when disconnecting from the fuel filter.
How to replace the fuel pressure sensor on the pipe (no use if the connector the pressure sensor screws into is leaking like in this thread).
Disconnecting it if replacing the Bosch high pressure fuel pump.
But nothing regarding replacing the hose itself. Useless!

So thank goodness it turns out it was quicker for a brave soul to just crack on and write it up

 

[TeddyRuxpin]

Oh, thanks for the kind words! Was expecting more of a 'stop spamming us with your amateur mechanic exploits you muppet!'

Here's where I'm at now: the pipe is back on, but as the resonator was not freely moving as the bolts were still in there, it makes refitting a little trickery.

Essentially, I'm not 100% confident that the pipe is sealed nicely: when I push the pipe in REALLY hard into the green o-ring end (into/near the turbo) - hard enough to hear/feel the 'pop' that people talk about which means it's secured in place - the long bolt which secures the pipe in place no longer lines up! It's actually 'past' the fitting hole. I hope that makes sense; the pipe is too far in on the turbo end, and you actually have to pull it back to have the (highlighted in pic) bolt align.

So you have to push it enough so that the pipe goes back on - but not too far. Suffice to say, I used a hammer on L-shaped bracket and knocked it gradually into place until the bolt was aligned.

Further, the end of the pipe which has the black o-ring (at the front of the car) really gives you no feeling that it's 'in' properly, either. There's no pop or feeling that it's right, it feels almost loose. Even the new, black o-ring was relatively loose around the resonator flange, fitting compared to the old one.

So I guess it's 'done' and I just need to re-assemble and hope that there's no vacuum leak. I'll keep an eye on it. At least I know what to look for - oily vapour/mist from either end (although the black o-ring end is hard to see when the plastic protector is in place), as well as potential power loss. Having said that, my father's green o-ring was leaking and his 265bhp version pulled like a freight train, and there were no errors!

Also, I'm pretty sure that the small screw I circled at the bottom of the pic is not correct - funny as it's only ever really been to MB (other than for brakes and MOT, etc)... I guess they dropped it and threw in whatever. Need to source the right one.

Finally, after I reassemble everything, the only thing left to do is clamp the clic-r hose clamps, but god damn it's hard to do it with needle nose pliers. I might just leave it until tomorrow as I ordered this: Draper 89791 Clic and Clic-R Hose Clamp Pliers: Amazon.co.uk: DIY & Tools (cheaper options available but it's an... investment?!)

Cheers!

Edit: thinking about it, I can't access the fuel filter clic-r hose clip with the batwing on, so if I can't sort it with regularly pliers, it'll have to wait until the clic-r pliers arrive tomorrow!!

 

[FiveAlive]

Oh, thanks for the kind words! Was expecting more of a 'stop spamming us with your amateur mechanic exploits you muppet!'

Another vote from me for this thread! A couple of winters ago I tried to replace the thermostat on my 265bhp OM642 W212, which required removal of the turbo-to-resonator pipe just to get one of the bolts out (the pipe on the 265bhp engine has an inconvenient resonance tube sticking out of it that covers the bolt). A you say, the space to access the resonator is minimal and I wasn't confident of being able to undo the bolts and, subsequently, refit them. In the end I gave up and left it to a professional and it has bugged me ever since. So it has been heartening to hear that you've had more success than me, and interesting to read your observations about getting it back together again.

I look forward to the next installment!

 

[MrGreedy]

Finally, after I reassemble everything, the only thing left to do is clamp the clic-r hose clamps, but god damn it's hard to do it with needle nose pliers. I might just leave it until tomorrow as I ordered this: Draper 89791 Clic and Clic-R Hose Clamp Pliers: Amazon.co.uk: DIY & Tools (cheaper options available but it's an... investment?!)

Definitely an investment.

I often go for replacement with stainless fuel clamps, as I find if you are mechanically minded and mechanically sympathetic, they are kinder on the pipework that using Jubilee clips as a replacement (that necessarily slide across the suface of the pipe, possibly slighlty damaging it as it is tightened). They are sized in tight tolerances though (about 2mm increments) so you need the correct size.
Oh, and no special tools

 

[TeddyRuxpin]

Thanks all. "Life events" and the rain have halted proceedings - literally all I managed today is the below video. Started raining and the engine was soaked a few moments after the video. Shame as I find working on the car therapeutic (and highly stressful at the same time when you don't have a backup car and live somewhat rurally!).

The other hose clip however is not so simple. Because of the high pressure fuel line, a torx bolt and the oil filter cap, it’s not really possible to get the clic-r pliers perpendicular with the hose as they need to be. So I think I will have to remove one of those things in order to sort it. Probably the torx bolt which holds a bracket that holds the oil filter housing. But the torx bolt isn't that easy to access with the tools I have - it's a series of 'creative problem solving'.

The other issue is that where I live, it’s going to rain straight until weds and the car isn’t under any shelter... and I need to drive it on weds, which isn’t ideal as I need to test and check that the pipe isn’t leaking in either end.

Cheers!

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[TeddyRuxpin]

Hi all,

Managed to quickly find a break in the rain and I think I'm all sorted! I've attached a video below of the first start up, not the most glamorous video but shows the engine ticks over without a hitch, about as smooth as I've heard/seen it run (although that could be confirmation bias!!!). Tried to leave the key in position 2 for the fuel line to get filled but didn't hear any unusual noises (like when I changed the fuel filter) - I guess it's only a short pipe. No error codes. The only 'gotcha' could be if there's a leak on the intercooler pipe seals, which I guess would only leak oil vapour when the turbo is pushing lots of air though. I haven't taken it for a proper drive, just idling and revving so far. Fingers crossed I don't have to worry about it again for a while.

To get the second hose clamp on, I had to remove the torx bolt that I've highlighted in pic 1. Then I could get in with the clic-r pliers.

To do stuff like that, you definitely need some kind of contraption, as I've shown in pics 2 and 3. I was lucky that I could rig this up using all sorts of adaptors from different tools! But it was so useful. You can get thicker flexible cable 'thingies' that allow you to transfer more torque to the bolt from the wrench, but they won't fit in as many tight places. But something like this is essential to work on this engine. And the tighter the fit, or if ideally it's all magnetised, the better, otherwise you'll lose half of it down into the depths of the engine/engine bay! Obviously one of those magnetised, telescopic things like this is a must, too!

Another tip is - you do need a torx socket set to work on MB engines but if you're in a pinch you can actually use a regular socket. Most of the torx bolts on the engine are E11 size, but you can also use an 8mm socket. That's what I've actually done in the thing I rigged up in the pics - and it doesn't chew up the torx head. So E11 = 8mm regular socket.

Will report back if a test drive goes okay... or if it doesn't!!!

Cheers!

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[TeddyRuxpin]

Funny - as soon as you're done, videos on youtube pop up as 'suggested' that could have been really helpful ~48h ago! The video below should take you to the right spot. You can see the ML has loads more room!

Although, more of a pain in the **** to get to the EGR valve from the looks of the rest of this video, so swings and roundabouts, ey.

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[TeddyRuxpin]

Hi all,

Just went for my first proper drive - to a drive thru corona virus testing center no less. The car was so smooth and pulled like a train, excellent. But after a few miles I thought hmm.. what's that.... what's that smell... smells like.. fresh diesel. Oh no....

Do you remember when I said 'the only gotcha' is going to be the turbo? Well, I was wrong... see 2 second video below. Lashings of Shell's finest V-Power premium diesel all over the engine!

The problem: the fuel hose clamps I bought were slightly too big. At least the one on the fuel filter was, anyway. I bought these and I believe them to be wrong for this purpose: Genuine Mercedes-Benz Fuel Filter Hose Clamp Binder 14.5-15.5MM A0049972090 NEW | eBay

I have attached a picture showing the old one on the left, and the new one on the right. You can see that the one on the right (which is the one purchased from that link above) is a bit bigger than the old one

I reused the old ones and am now hoping for better luck.... just have to get this smell of diesel out of.... everything.

So for anyone doing this job - BE 100% SURE THAT YOU HAVE THE RIGHT SIZE CLAMPS! Or follow @MrGreedy's advice and use screw clamps.

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[TeddyRuxpin]

I'd guess this is the correct one: Genuine Mercedes-Benz Fuel Filter Hose Clamp Binder 13-14.5MM A0069971890 NEW | eBay

13-14.5mm rather than the 14.5-15.5mm ones I bought...

Hopefully I'll be fine using the old ones. I changed both sides just to be sure.

Edit: Confirmed by MB parts dept Cardiff that it's the 13-14.5mm clamps that are supposed to go on either end of that hose. You wouldn't think ~1mm would make the difference to cover your engine like that, but the evidence is there for us all to see.

Hope this helps at least one person!

 

[MrGreedy]

I'd guess this is the correct one: Genuine Mercedes-Benz Fuel Filter Hose Clamp Binder 13-14.5MM A0069971890 NEW | eBay

13-14.5mm rather than the 14.5-15.5mm ones I bought...



Edit: Confirmed by MB parts dept Cardiff that it's the 13-14.5mm clamps that are supposed to go on either end of that hose. You wouldn't think ~1mm would make the difference to cover your engine like that, but the evidence is there for us all to see.

Well, take heart in the knowledge that your trials and tribulations are at least causing others to smile (with you in sympathy, not at you, because I've been in far too many of these situations myself to point and laugh)

As per my earlier recommendation, this is why the fuel line clamps come in 2mm(ish) increments. Should in most instances be easier to get a nice flexible driver in there to do it up as well if you place the clamp correctly.

For other brave souls reading this, I would always measure the hose with a vernier caliper, then buy the correct size fuel clamp and one size either side, and physically try them out for fit if in any doubt. (or if you're obsessed with having the right kit like me, then buy an assorted box of stainless fuel clamps so you will have them available for years)

 

[TeddyRuxpin]

That video is pretty funny, though!

 

[W1ghty]

I'd guess this is the correct one: Genuine Mercedes-Benz Fuel Filter Hose Clamp Binder 13-14.5MM A0069971890 NEW | eBay

13-14.5mm rather than the 14.5-15.5mm ones I bought...

Hopefully I'll be fine using the old ones. I changed both sides just to be sure.

Edit: Confirmed by MB parts dept Cardiff that it's the 13-14.5mm clamps that are supposed to go on either end of that hose. You wouldn't think ~1mm would make the difference to cover your engine like that, but the evidence is there for us all to see.

Hope this helps at least one person!

The clic-r clamps are different on each fuel filter hose , one is bigger than the other .