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

[TeddyRuxpin]

Hi all,

Noticed a bit of a smell in the cabin for the past few days. Looked around the engine and found this the leak in the obvious place in the picture. Could be the hoses, could be that... sensor? I assume that's some kind of fuel (pressure?) sensor?

Does anyone know what that sensor is, and/or has experienced a leak like this before? Best course of action when troubleshooting? Tricky fix or easy DIY?

Sorry for all the pics, just trying to offer as many angles as possible! First pic shows after I wiped it away in London a couple of hundred miles ago, then the second pic shows after it's leaked again.

Thanks!

Ed

 

[ChipChop]

Hi all,

Noticed a bit of a smell in the cabin for the past few days. Looked around the engine and found this the leak in the obvious place in the picture. Could be the hoses, could be that... sensor? I assume that's some kind of fuel (pressure?) sensor?

Does anyone know what that sensor is, and/or has experienced a leak like this before? Best course of action when troubleshooting? Tricky fix or easy DIY?

Sorry for all the pics, just trying to offer as many angles as possible! First pic shows after I wiped it away in London a couple of hundred miles ago, then the second pic shows after it's leaked again.

Thanks!

Ed

Picture 5 has a close up of a hose which appears to have a part number on it in blue/ green. Could be a cheap fix if you can get away with ordering the hoses and some fixings from your local MB dealer. Worth a try.

 

[TeddyRuxpin]

Still googling - just found this: Mercedes-Benz om642 fuel hose with pressure sensor a6420706181 | eBay

Seems like all of that comes as one unit, for around £80. I'll see what MB charge for this part tomorrow.

Looking at it, just wondering if the big silver intercooler pipe needs to come off to get it fitted.... if anyone has done it before, let me know!

 

[TeddyRuxpin]

It looks like the longer pipe goes directly to the fuel filter. I'm hoping that it can just slide under the intercooler pipe and doesn't require the big pipe nor the thermostat to come out!

 

[MrGreedy]

It never stops with high milers does it!?

Looks like it's leaking enough out that you're getting standing diesel sitting on your Bosch fuel pump A6420700801.

I think it's a good shout to change that sensor and hose assembly out.
Check MB Grangemouth for the part price as I keep telling you and mention you're a forum member


It looks a relatively easy job.
One end is connected to your fuel pump as you can see.
The other end is connected to your fuel filter, which is a regular service item and relatively easily accessible.



Let us know how you get on

 

[TeddyRuxpin]

Cheers! Yes, I changed the fuel filter recently. Will be calling around tomorrow - will definitely give Grangemouth a go - but will also check Cardiff and Bridgend just on the off chance that they have the part in stock!

 

[TeddyRuxpin]

If i could fix it for ~£80, I'd be well happy.

It's like a strange stockholm syndrome - it scares me with a fault, then I'm relieved/over the moon that it's 'only' another £100 to fix!!!

Edit: Of course, I am hoping that the part number A6420706181 is for the sensor and hoses and bracket, and not just the sensor... we shall find out tomorrow...

 

[TeddyRuxpin]

Hi all,

Well, it's £140.40 new from MB Cardiff. They have it in stock and it's 5-10 mins from my house.

MB Grangemouth are doing it for ~£130, but it's not in stock and they would have it here by Tuesday or Weds, so I'll probably just go grab it from Cardiff. The guy from Grangemouth was really nice though, would happily give them my business in the future.

More than I was expecting/wanting to pay, but hey... it's a fuel leak, needs sorting. Who needs to eat dinner anyway?

Will try to take some pics of changing the part so that it can be useful to someone in the future...!

Ed

 

[TeddyRuxpin]

A small update - I went to get the part. I called up and asked for a members club/forum discount, and obviously MB Cardiff doesn't do that, but he said he would give me a 'loyal customer' discount and get it for £135 instead of £140.. Fair enough... I get there and it's £137....! Whatever...

To get me there, I wrapped it in silicon wrap which I think helped... not pretty but might have saved a few drops. This stuff is self-adhering and a bit of a life saver in general, great to keep some in the car.

Anyway, I managed to find a video of the leak, please see below. I also saw a couple of nice cars in the carpark... enjoy! I considered part exchanging my W212 for the GTR but thought, you know, that green stripe isn't really my style.

I will attempt this tomorrow when it's a touch warmer and not 0 degrees... I'm REALLY hoping that it doesn't require me taking the intercooler pipe off!

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[MrGreedy]

I will attempt this tomorrow when it's a touch warmer and not 0 degrees... I'm REALLY hoping that it doesn't require me taking the intercooler pipe off!

Nice pictures of the cars and good to get out when it's not chucking it down!

P.S. you know you're just kidding yourself and that the batwing and intercooler pipe are both going to have to come off

 

[TeddyRuxpin]

Haha, yeah I know. Good job I already have the seals for that intercooler pipe, although I didn't do a great job trying to get my dad's intercooler pipe off last time (I was in a rush). I had to leave and ended up giving up and taking it to an indie, who did it in 1/2 hour. I lost -10 'man points'.

I think getting the resonator box torx bolts off is a nightmare... maybe have to get under the car? Would like to avoid that, if possible!

The W212 has the fan in the way of accessing those resonator bolts easily, some videos online show the ML with the OM642 where there's much more space.

 

[MrGreedy]

For the resonator (which I haven't done but talked with Olly at PCS about at end of December) he confirmed what I'd read elsewhere. Remove the top bolt. Only loosen the bottom bolt. This gives the resonator enough wiggle to get the turbo to resonator pipe off. Easy buddy....


Apparently

 

[TeddyRuxpin]

Thanks! But to loosen the lower bolt, I don't think you can access it properly on the W212 as the fan is in the way. In the ML and stuff I see online there's oodles of space - to get access for the W212 I think the access is largely from the bottom, which if you're a proper mechanic with a lift, is a doddle.

Maybe I just don't have the right tool - maybe a small socket wrench with the torx on would work (I don't have one)

Anyway, I haven't tried for a few months, so will see how I get on and bore you all with the details tomorrow! I hope I am just overthinking it

 

[TeddyRuxpin]

Alright - an update - I didn't have time to tackle this early today so only took the batwing off and had a look around and my conclusion is - it's a bit of a nightmare.

Let me explain - firstly, yes, the big intercooler pipe 100% needs to come off. It's also possible/probable that the thermostat needs to come off, along with that big black coolant hose. Probably at least the thermostat though, but I will try to avoid it if possible. In the first picture, the top two ovals show roughly where the bolts are for this wretched pipe!

Secondly - everyone always just says 'oh, just remove the bolts from the resonator and the intercooler pipe will come right out' - well, check out the pictures (sorry they're not the best angles). How is that possible on the W212, without removing the radiator fan? There's only a couple of inches of room. The ML350 in most videos I see has at least half a foot of space between the fan and resonator! I can't even see the other bolt on the resonator box.

Any thoughts, ladies and gentlemen?

I'm going to order a small socket set and more torx bits so I'd have a fighting chance of getting that red-circles bolt out (although it not falling on the floor while I do that is another thing) and maybe that will be enough to get it free. They won't be here until Monday though...

Going to do some googling to see if I can find the other screw on the resonator.

Really don't want to have to put everything back together again, move the car to somewhere I can put it on ramps (to remove the undertray in order to remove the fan?), and then start again!

Yours sincerely,

Cold & Annoyed

 

[TeddyRuxpin]

For example, my resonator looks nothing like the video below, where there is space to move, and two clear bolts.

My dad's 265BHP 2010 W212 is the same design as mine, so it's not a quirk of the 231BHP engine, or my particular engine.

If I'm looking in the wrong place for the bolts for that resonator/silencer box, please let me know I'm all ears!

(This video link below will start in the right/relevant position.)

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[TeddyRuxpin]

Alright, I might have found one of the bolts, on the right. See attached. I loosened it a bit, but gosh, it's so tight in there I'm scared to remove it as it will just fall, unless I can get a magnet down there.

I think the tiny torx screw I highlighted earlier was a nonsense - it's not one of bolts holding the resonator in place.

The trick is to find the other bolt holding this god forsaken thing in place...!

Edit: finally found the location in this video, at ~4mins20sec if anybody cares to watch. As you can see, the entire front of the car is removed (fan, grill, bumper, etc - he's doing oil cooler seals). That location is quite frankly mental - not sure if it's possible without at least removing fan, but I'll bloody have a go... even if I can just loosen it enough to get the intercooler pipe out!

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[TeddyRuxpin]

The closest I’ll ever get to experiencing ‘the thrill of the hunt’

 

[MrGreedy]

Alright, I might have found one of the bolts, on the right. See attached. I loosened it a bit, but gosh, it's so tight in there I'm scared to remove it as it will just fall, unless I can get a magnet down there.

I think the tiny torx screw I highlighted earlier was a nonsense - it's not one of bolts holding the resonator in place.

The trick is to find the other bolt holding this god forsaken thing in place...!

Edit: finally found the location in this video, at ~4mins20sec if anybody cares to watch. As you can see, the entire front of the car is removed (fan, grill, bumper, etc - he's doing oil cooler seals). That location is quite frankly mental - not sure if it's possible without at least removing fan, but I'll bloody have a go... even if I can just loosen it enough to get the intercooler pipe out!

Yes, that's the one! He only loosens it in the vid. But can you get to it! That's the question!
Wishing you the best of luck at this wonderful time of the year to be doing this sort of thing outside

 

[TeddyRuxpin]

Haha!

Yep, I loosened them both and it was enough to get the pipe out, but was careful not to actually remove them I had to use a combination of all sorts of really long and some flexible tools to get it all out. I can't believe how hidden that left side bolt is!

In case anybody has to do this and finds this thread - for the replacement fuel hose, you can see the two bolts highlighted in my first pic. The one on the right is under the silver intercooler pipe, but as you can see in the second picture, again, a ridiculously long socket set saved the day. So mercifully, you don't need to take the thermostat off, and clearly you don't need to take the fan out (if you just so happen to have the right flexi socket tools!).

I did take all the air intake system off, including whatever the black plastic thing with the aircon stickers on, that's just above the grille. Gives a couple more inches to work.

Also had absolutely loads of fun with the fuel hose clic-r clamps - I don't have the proper clic-r pliers. Fortunately I do have two new clamps - but I might order the right pliers (they'd arrive monday) and just leave the re-attachment of the clamps until then. I don't need to go out!

So currently, the new hose is on and bolted in, sensor attached etc as you can see in the last pic - tomorrow I need to reattach the pipe with new green and black seal, retighten the air resonator box bolts (hope that all goes smoothly), and reassemble everything. The clic-r clamps are thankfully accessible once everything is back together, so I can leave them until Monday if I can't use my needle nose pliers to get them on (they are on but not clamped).

Calling it a day for now, back is killing, more tomorrow

Cheers!

P.S. I wish we could edit our older posts so I could tidy up this thread and consolidate it a bit!

 

[clk320x]

What a brilliant thread which will massively help out future members with the same issue.

A big thumbs up from me