W210 Diesel Injector Sealing Washer Extraction

Discussion in 'Engine' started by skemball, Dec 12, 2008.

  1. skemball

    skemball Hardcore MB Enthusiast

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    Read with interest lots of posts on the dreaded CDi injector removal problems.

    I have just removed the rear-most (No. 6) injector due to blow-by of the sealing washer. Fortunately for me it could only have been blowing for 150 miles as I replaced a glow plug last Sunday and it definately wasn't blowing then so the gunk build up was minimal. It still took a lot of persuasion to remove and found that cleaning thoroughly around the base of the injector first then liberal soaking with diesel & WD40 did the trick to free it up so it could be rotated a bit at a time then lifted a bit, then pushed back in etc. etc.

    Anyways the copper washer is stuck at the bottom of the hole - any tips to remove?
    I have a good selection of large diameter drills and an air compressor to pressuris the cylinder but would need to accurately grind the correct angle on the drill or run the real risk of mucking up the sealing face if I drill down too far. This is to be avoided at all costs so would prefer something less invasive.
     
  2. OP
    OP
    skemball

    skemball Hardcore MB Enthusiast

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    Job done with no issues - even removing the sealing washer was a doddle with my home made 'pick'


    If anyone wants to know what tools i made up to clean the injector hole and remove the washer send a reply.
     
  3. Dieselman

    Dieselman Banned

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    Reply sent.
     
  4. proser

    proser Hardcore MB Enthusiast

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  5. OP
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    skemball

    skemball Hardcore MB Enthusiast

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    I used what I had to hand so to speak so to remove the washer i had an old scriber with a right angle tip that had seen better days so ground this to a taper so that it would act a bit like a wedge fitting through the hole in the washer and then pushing it between the washer and the head - no effort was required so no damage to the surface of the head.

    The next job in cleaning up the bottom of the bore i ground down the handle of a broken 1.2" ratchet so that i could wrap a tape one turn of 1000 grade wet & dry. got it so that it was a snub fit. I didn't want to again damage the seat of the hole and the wet/dry was used to clean the side of the bore. The end of the ratchet conveniently had a slight bull nose radius on it so didnt really touch the seat of the hole.

    Last job to clean up the extremities of the bottom of the hole i cut a piece of 1.2mm thick aluminium sht to the correct bore size and profiled the end so that as i rotated it in the hole it cleaned around the outside of the hole. I didn't touch the bottom surface of the hole.
    100_4350-2.jpg


    100_4347-2.jpg


    Lastly - why did it leak? Well over 147,000 miles I guess the compression acting on the washer due to expansion and contraction resulted in a reduction of compression. This is why a turning setting is specified rather than a torque figure. They want compression on the washer, not simply a torque figure that will vary depending on whether the threads are lubricated, dry etc. Looking at the end of the injector you will notice that a small part of the seat is reduced width. It is at 9 O'Clock in the picture and appears as a slightly darker area. Combined with the washer being a sloppy fit in the hole (as evidenced by the compression marks on the washer being off-centre) the result is that in a small area of the injecter mating face the contact area was only a couple of mm wide.
    100_4344-2.jpg

    These sealing washers (from MD dealer) are conical on one side and flat on the other. I fitted mine with the conical side down but with hindsight should have maybe fitted it facing the steel injector rather than the alloy head. This is part of the design to compress and spread the seal.

    The dealer stated 7nm then 90degrees, then another 90 degrees. I gave mine a total of 270 degrees because at 180 degrees I knew it had more to go before risking a stripped thread. The old bolt was exactly the same length as the new bolt and to be honest a 5mm steel bolt is gonna strip the alloy thread before it stretches as there is no indication in the construction to show it will stretch very easily.

    I checked the other injectors and gave them all a nip of slightly less than 90 degrees. They all 'cracked' then turned without excessive effort.
     
    Last edited: Dec 15, 2008
  6. franey

    franey Hardcore MB Enthusiast

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  7. OP
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    skemball

    skemball Hardcore MB Enthusiast

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    Good idea as those engines that get jet-washed on occasions could likely end of with moisture getting between the clearance of the injector and the hole and accelerating corrosion/seizure.

    I keep my engine clean but avoid high pressure washing. I used copper slip on the injector body - there was barely a hint of rust on the body of the injector but in another 150,000 miles should the seal fail hopefully this will also prevent the coke from gumming up too much.

    The morale of the story really is to lift the bonnet once and week and listen carefully for any sounds of blow-by. That way you will avoid the trauma of of seized injectors.
     
  8. knowlep

    knowlep New Member

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    Seized Injectors

    We had an ML270 that we took in cheap part ex and on lifting the cover found all 5 injectors leaking so badly that the whole of the compartment was level front to back with carbon - an unbelievable sight. It took a day to carefully pick away at it and we had to use "Carb Cleaner" spray to soak into the injector wells to soften and free them. Even then it was a right game to get them out. :crazy:
     
  9. OP
    OP
    skemball

    skemball Hardcore MB Enthusiast

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    I know we all take modern engines for granted but that must have been making some kind of noise. I only had one injector leaking but it was quite audible with the bonnet closed.

    Myself include generally take reliability for granted but it does pay to lift the bonnet once a week - with the engine running.

    Sure sounds like a bad case of 'granny's toffee'
     

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