C220cdi om651 has me baffled

[Kev555]

I had similar problem with my OM651 and cylinder 3 as well back over a year ago, dont quote me but as far as i can remember i switched injectors around too to see which injector was faulty or was it wiring looms? I found strangely enough that even changing injectors around cylinder 3 always turned out to be the cylinder at fault. Its sounds crazy but the ECU was playing tricks with me. A new set of injectors cured the problem, My advice is get a set of injectors tested then try them as cylinder 2 injector from memory was the worst injector when got my old ones tested.
The cylinder balance you posted looks all too familiar to me as well Matty
Just to add ive read through all your posts and ive jumped through a few of those hoops and I'm well convinced its injectors as you've ruled out other things as I did . I discredited the injectors myself for long enough mainly because of the cost involved but wish I had tested them earlier

 

[Mattyb1984]

I've actually read through your threads Kev which is why I too am convinced it's the injectors but leak off tests, it not moving from cylinder to cylinder like other cars do had me second guessing which is why I was reluctant on buying a new set of injectors. I have however found a few things out about these om651 engines. The main thing being not to buy one with issues

I will order some injectors tomorrow and post the results as soon as they come.

 

[mattkh]

Hi
Are these injectors piezo ones?

 

[Kev555]

Yes I believe mine were as they were Delphi

 

[Kev555]

Yes Matty I thought the same after I bought mine and discovered issues, but after going bald from pulling my hair out over a period of time I'm in a happier place now with less hair, they seem a good engine when running sweet and a nice response from remapping

 

[Malamadre]

Hello, sorry to rush in like this on the forum. But I came across your topic via google and I have exactly the same problem with my c class.

The car isn't moving now since the start of december 2020. Pulled almost half the engine apart but could not find anything. I'm starting to lose my mind.

Have you figured out what the problem was/is with your car? I would highly appreciate it.

 

[Mattyb1984]

Hi, yes to update this thread both cars were finally repaired. So the first repair was on the engine freshly rebuilt, this turned out to be a sticking valve on cyclinder 3. After reluctantly pulling the head i found it. So then i moved onto the second car and proceeded to remove the head also. This one i found the piston on number 3 had worn, replaced piston and rings.

The lesson i have learnt would be to ignore the diagnostics and compressions readings from them and go back to basics. Because i was following the diagnostics i spent 4 times as much time on these two cars.

 

[ajlsl600]

Early 651 engines can be a pain to bleed, there is a program on star just bleed and even then you have run thru it several times.

Its a constant thing is it not.makers making Even the most basic of tasks MORE difficult.given that we mastered this task more than 80 yr ago.one must conclude this is deliberate act /design of maker.no ?

 

[ajlsl600]

Hi, yes to update this thread both cars were finally repaired. So the first repair was on the engine freshly rebuilt, this turned out to be a sticking valve on cyclinder 3. After reluctantly pulling the head i found it. So then i moved onto the second car and proceeded to remove the head also. This one i found the piston on number 3 had worn, replaced piston and rings.

The lesson i have learnt would be to ignore the diagnostics and compressions readings from them and go back to basics. Because i was following the diagnostics i spent 4 times as much time on these two cars.

Wot a surprise ,not!!!

 

[ajlsl600]

So valve sticking ,must have been in open position , so was piston pushing it back up or there was clearance ,also must have been bad ? To overcome spring trying to shut it ? Valve bent ? In either case would have though comp test would have to show something ? If now running ok grand .

 

[MinionBob]

Who would have thought it; two different vehicles with identical issues but different solutions. I wonder what the chances of that are?!

Thanks for the update

 

[Malamadre]

Thank you for the reply. These were also some of the things I kept in mind but ignored because I couldn't believe this would happen with such a young car even though it has almost 180k miles.

Now time to figure out wich one is the case with my car.

 

[Kev555]

Start off with the basics Malamadre like I was told on here by a few members that have been through it like compression test first and work outwards