E class diesel injector woes

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New Member
Jan 3, 2024
perth & kinross
Hello All

This is not good is it - ?

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By way of background... I have a 2007 2.2 diesel E class, 152000 miles on the clock. I had the car in for an MOT last month and whilst having the MOT work done the mechanic also diagnosed an issue with an injector that was producing a ‘hiss hiss’ sound. I have to say I never noticed any issues with the car's engine/overall performance prior to the visit.

He installed a single new injector & copper washers. I recall him telling me the bad injector was difficult to remove. On return of the car to me the car was vibrating noticeably whilst at idle. I took the car back, he performed more work and the roughness subsided for about 3 weeks only for the roughness & visible discharge to return yesterday. I visited the garage today - they cannot look at the car for a week due to being busy.

Can anyone comment on what has resulted in the leak returning after 3 weeks and what the mechanic must do from here on to fully resolve the issue ? I also understand from comments that the new injector must also be coded ? I do not know if coding was done as I only discovered about coding last night. But after viewing the video the issue seems way beyond coding an injector.

Today the mechanic referred to possible cylinder head wear which could hinder any remedial work he might do to fix the issue and ultimately render the car uneconomical to fix. My understanding ( could be wrong ) is that the injector may not align correctly if the old bad injector has worn inside the cylinder head ?

All the above is clearly not my area of expertise so excuse any errors.

I look forward to viewing your comments & suggestions.

The mechanic should have noticed that the injector seat needed recutting before installing the injector.
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Take out the injector and recut the seat, new washer and bolt.

I'm guessing that the replaced injector wasn't zero'd and the teach in process carried out.
Maybe it wasn't even coded to the ECU?

He should do the re seat for free, as it's a failure of the work he did. Otherwise take it to an MB Indie who will understand the requirements better. It would really need to go there for the teach ins, although the coding can be done by lesser machines than Star.
Thanks, I will return to the garage.

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