OM642 injector keep getting blow-by!

[Aston Dabb]

Hi all, I’ve got an E350 CDI.. I have changed the injector washer & bolt as per WIS document on cylinder 2 twice; it is now chuffing away for the 3rd time. What is causing this?

 

[M80]

Did you ream the bottom of the injector hole?
If so how did you ensure the bottom of the hole was clear of debris, clean, and with continuous circumference polished rings?
What torque down procedure did you follow?

 

[mersum1es]

And did you cleaned thread hole too? Is injector side sealing surface clean and flat?

 

[Mark A]

Check condition of the sealing face on the injector. I have had issues in the past with my ML270 and after replacing seals I still had chuffing. recut seats, again no different - eventually traced it back to the injector itself.

 

[Doug1234]

When I replaced injectors in mine I annealed the new seals and then fitted them on injectors and run the seat cutter gently on them just to ensure they were flat.
Is the seat cutting tool the right size ?.

 

[mattkh]

..... I have changed the injector washer & bolt as per WIS document on cylinder 2 twice

How many miles between the changes..?

 

[Uncle Benz]

As others have said, recut the seat in the head, then remove the cutter from the tool and use it to clean the face on the injector too. Closely inspect the bottom part of the injector for hairline crack up the side of the nozzle cap

 

[Aston Dabb]

Got injectors tested and when pulled injector out we found it had actually heavily damaged the bottom of the injector. We changed the injector; all good so far