270 CDI (om612) hpfp failure opinions? W209 CLK

[smanderson117]

Hi all, looking for opions based on the info below: (CLK 270 CDI with 161k)

I had intermittent issue with car sputtering then cutting out requiring turn fully off and back on again then it was fine. It brought up engine light and code P0251 (injection pump metering control), it would do this once a month or so until it did it on the motorway and I was stuck, car would start back up as before after fully turning of and would idle fine but then any load as you go to pull away even gently would cut it off again. Car recovered and I changed the fuel pressure regulator for Bosch genuine item. All seemed fine, car would take slightly longer to crank/start up but was running fine, would sometimes smell really dieselly like an old bus.
It has now cut out twice in 2 weeks with same issues and is throwing the same code. I believe HPFP is probably failing hence longer start time/cranking and not supplying enough fuel which gives the code. Could it also be potentially the injectors? They seem to be original so quite old now and I have had them out twice now, once to change injector seals as had slight black death and then I had to change a cracked rocker cover so had to remove them again. Each time I cleaned them with EGR/carb cleaner and a cloth, nothing more aggressive. Would it be worth doing a leak off test first to see if injectors are supplying/returning correct and even amounts of fuel before firing parts cannon at reconned HPFP at circa £250? Anyone have experience of similar situations even after changing FPR?

Thanks all for advice and input, car is really testing my patience lately!

 

[mersum1es]

See if you have air bubbles running in low pressure line. Yes leak test is pretty easy and cheap test. Usually OM61X HP pump failure is seen as a leak outside.

 

[smanderson117]

See if you have air bubbles running in low pressure line. Yes leak test is pretty easy and cheap test. Usually OM61X HP pump failure is seen as a leak outside.

Thats a good shout, would point to the seals on HPFP if there are bubbles correct? I'll try get in for a leak off test! No leak on the outside, dry as a bone, however it did have an MOT failure years back way before my ownership for fuel leak at front of engine and then a pass a few days later so I wonder if it has been repaired previously.

 

[mersum1es]

Fuel leak front is usually HP pump leak, seal under cylinder head fails. No leak outside because low pressure side is actually vacuumed by aux pump. Air bubbles in clear lines are due to hardened o-rings of low pressure hose connector (VERY common issue), or brittle hoses itself. Air CAN be drawn from filter hose, leaking filter housing, fuel cooler (if exists in this model) or cracked t-connector somewhere.

 

[smanderson117]

Fuel leak front is usually HP pump leak, seal under cylinder head fails. No leak outside because low pressure side is actually vacuumed by aux pump. Air bubbles in clear lines are due to hardened o-rings of low pressure hose connector (VERY common issue), or brittle hoses itself. Air CAN be drawn from filter hose, leaking filter housing, fuel cooler (if exists in this model) or cracked t-connector somewhere.

Thank you, will have a thorough look tomorrow see what I can find! The clear lines I dont recall seeing at any point, will have a look tomorrow might require some cleaning as it's grafted in there they'll probably be black lines before a blast off!

 

[mersum1es]

Someone could have changed black hoses, original are clear lines (low pressure) could be covered by plastic hose covers.

 

[smanderson117]

Turns out yes they had hose covers on. I peeled them all back on all the clear hoses I could see, one to end of fuel rail, one to fuel filter and some around the HPFP and checked when both running and none running. No air bubbles that I could discern, I assume usually it looks like the bubbles when you're bleeding brakes? I might order a leak off test kit from amazon as they're only <£30. Is there a specific procedure/expected fuel quantity for Bosch injectors that anyone knows?

 

[mersum1es]

20ml/min

 

[smanderson117]

Thanks @mersum1es !
I ran the car for 4 mins at idle (already warmed up), got the result as below. Its from left to right injector 5 -> 1 so injector 5 is leaking off more than the others, however not sure if it's that much drastically more to indicate an issue. The plot thickens however as that was the injector which had black death previously so could be damaged. It also had a "3" on it as opposed to all others having 2 which seems odd? I've read something about this indicating whether the injectors need coding etc. Unsure as to how to proceed now really! The cranking time isn't abhorrently long but definitely longer than it was before. Thanks for all thoughts and input

 

[mersum1es]

That is not looking horrible, though bit high side. If I recall right, all leaks should be inside 20-25%, and thats ok too. Measure again when engine stone cold. Usually leak problems start at cold.

Yes, that is coding number. Not all OM612 engines requires a coding (only way to know is go to ECU and see if there is option available), and even they would, problem of wrong coding is usually uneven idle, slight knocking etc.

 

[smanderson117]

Thanks, I will repeat when I get chance on stone cold engine Yes I didnt think that it was too much higher but good to hear your thoughts on it also!
Gotcha, very odd one injector is a 3 and all other are 2, makes me think maybe been changed in the past already! Will report back with another leak off test on stone cold engine haha

 

[smanderson117]

So, I took your advice @mersum1es and did another leak off today from stone cold, first image is running again for 4 mins for comparisons sake and second image is ran until an injector filled a bottle to 100ml which number 5 (confusingly the first one) did. I'd still say they're not too far off from each other as a percentage however? Not the smoking gun I was after, I fear I still might need to change the HPFP after all this and not just an injector as I (however foolishly) hoped!

 

[boxer 01]

Get your pump refurbished. I don't know where you are but I had mine done by PF Jones in Manchester it's been fine and at a fraction of the cost of a new one.

 

[smanderson117]

I think I might buy a refurbed pump (with warranty) on exchange basis as I need the car back up and in action asap really. It's £245 so not terrible I guess. I'm in Warrington but recent PF Jones feedback is all 1 star

 

[boxer 01]

I have to admit Customer service left a lot to be desired, but I took my pump in and asked for a summary of parts changed and tests carried out. They tried to charge more once they had started doing the pump saying the original price quoted was for a different type of pump but I didn't cave and all was well. The company has been going for years and I got the impression if you didn't know what you were talking they would try it on, so just be on your guard.

 

[smanderson117]

I have to admit Customer service left a lot to be desired, but I took my pump in and asked for a summary of parts changed and tests carried out. They tried to charge more once they had started doing the pump saying the original price quoted was for a different type of pump but I didn't cave and all was well. The company has been going for years and I got the impression if you didn't know what you were talking they would try it on, so just be on your guard.

Thats fair enough I suppose if all worked out in the end

I bought a refurbed pump from ebay, fitted that and if anything the issue is worse. Makes me think maybe there is a leak somewhere in the low pressure fuel lines, exacerbated by having them off and on the HPFP during the swap. Ordered a genuine o-ring seal kit for all the low pressure lines. Couldn't see any air bubbles previously but will try this anyway. If problem persists will have to take to a specialist i guess

 

[mersum1es]

Can you read live data, rail pressure when cranking?

 

[smanderson117]

Can you read live data, rail pressure when cranking?

Unfortunately not. I have a cheap chinese code reader and I bought the torque app, but unfortunately grayed out option for fuel pressure. I suppose that will tell all won't it once that data is read. There's not much left to replace in the fuel system now, shy of the LP lines themselves, the front pressure sensor and the injectors so I must surely eliminate the issue one way or another soon Cut again again twice today, not ideal. Worse when it is hot too, cranking taking ages when pootling around town doing errands

 

[smanderson117]

Well all the fittings for the LP lines turned to dust as I tried to remove them so I've ordered some new complete low pressure lines. One of the 3 was NLA from mercedes so went for a "gates" branded aftermarket one, hopefully will be ok. Will put a light smearing of grease on all the o-rings to help them seal too. Least I can just rip the lines off now without worrying about preserving the clips etc
If this doesnt fix it, specialist time I think. I just want to enjoy the car now

 

[robparker]

That's odd, I just bought the 3 low pressure fuel lines for the same 270cdi from mercedes last week and the all arrived next day