Mercedes Diesel Injector Advice – Sprinter and others


Having rectified many ‘chuffing’ injectors and dealt with the famed ‘black-death’ on many sprinter engines and its close derivatives used across the complete range of Mercedes Diesel vehicles, I can honestly say that the hold down mechanism used to secure the injector in the head is definitely the engines number one Achilles heel.  I am afraid that a single 6mm cap head pin used on one edge of a single steel injector clamp, tapped into an aluminium head is just engineering madness from a commercial maintenance point of view.  Now that’s  out of the way – rant over – how do we best deal with this problem and get that vehicle back on the road.

You will be reading this if you have begun to hear the release of combustion gas from around the engine bay of your vehicle (chuffing) or you may have discovered a black shiny coal like deposit building around one or several injectors (black-death) in addition to lacklustre performance and increased fuel usage. Before we carry on, it is of great importance to bring to your attention that we are dealing with a direct injection fuel system with operating pressures around 23,000 psi or 1600 bar!  This fact is to be remembered when working on a running system, when either fault finding or during rectification – Serious injury may result if you do not respect the obvious dangers involved.  If you cannot identify the dangers of working with very highly pressurised fuel systems you would probably be better to entrust the work to a specialist.

If the ‘chuffing’ has been noticed early on, none or very few ‘black death’ carbon deposits will be seen, just wetness from ejected diesel resulting from the failing combustion process forced up around the leaking injector out to atmosphere on the cylinder head.  If carbon deposits are present then they will have to be completely cleared and chipped away with a blunt screwdriver/scraper and vacuumed away as you go.

Injector Black Death Mercedes Sprinter

Injector Black Death Mercedes Sprinter

Because of the close proximity of other injectors it may be difficult to identify exactly which one is the culprit.  If the leaking injector is not obvious, then clean down the area with Gunk or other degreaser and dry off the area (engine off of course) completely.  Using 2 inch strips of old brown paper cut from the envelopes of your unpaid bills (joke) make hollow tubes and wrap them around the injectors, fastening the ends together with a paper clip. Do this for all suspect injectors.  Start the engine and watch for the darkening/spotting of the brown paper with diesel spray, this will indicate quite clearly where the problem lies.

Once identified the work can begin – Run the engine until nice and warm then turn it off and remove the keys.  Remove the turbo supply hose to the inlet manifold and split the composite intake manifold by removing the pins that secure it to the lower section.  Remove the two pins that are also fastened to engine brackets at the rear and front of the head by the fuel filter.  Lift off the manifold and stuff the remaining open ports with paper/cloth to prevent bits dropping inside.  Check the gasket at the back plate/cover of the upper section of the inlet manifold as this is prone to squeezing out causing turbo boost leak and is this a good time to take a look/plan to rectify.

Remove completely the steel fuel supply pipe from between the leaking injector and the fuel rail along with its injector electrical connector; tie this cable out of the way of the work area.  Remove the long single 6mm torx bolt that secures the injector clamp and place it safely to one side with the clamp itself.  Inspect the threaded portion of the 6mm bolt if it is damaged or showing heavy signs of alloy material deposited on the threads then further action may be needed later on to rectify the threads in this failing all important tapped hole.

The next part of the procedure is ‘make or break’ for the DIY repair and is the point of no return so please take heed.  Try to rotate the unclamped injector, if it moves freely by hand then great, if it won’t budge try a little more force – but not too much.  If it’s seized then at this point re-assemble the engine and take it to a diesel specialist as damage to the injector or head can be very expensive indeed and botched repairs will easily exceed the cost of it being done by a professional in the first place – you have been advised.  If the injector rotates, begin to pull it upwards whilst twisting the body, if it jams, twist it the other way and work it using some penetrant or WD40 in the area around where it enters the head.  In some cases the injector lifts out instantly, in others it can take hours of wiggling and fiddling, don’t be tempted to use hammers or heavy tools to do this job as commonly expensive damage results.  The image below shows damage to a rocker/cam cover caused by levering against it to extract a stubborn injector.

Damaged Sprinter Rocker Cover

Damaged Sprinter Rocker Cover

Once the injector is out, clean it off and place it safely out of the way then recover the single copper washer from the hole in the head that forms a gas tight seal for the injector against the aluminium cylinder head.  Use a torch to inspect the injector seat in the cylinder head, it will likely be blackened and carbonised, this needs to be cleaned off and in severe cases re-cut to present a perfect sealing surface.  I have in the past had great success using a wooden dowel, rather like the ones used on a valve grinding hand tool.  Using contact adhesive stick a square of medium abrasive paper to the end of a flush cut dowel, allow the glue to dry then trim round with scissors.  Pop this tool down the hole and clean the seat as if you were grinding in a valve.  Inspect it regularly and if there are slightly deeper grooves remaining keep going with new paper until clean and flat.  Now the top tip, it will be necessary to purchase a new copper sealing washer.  The best thing to do here is purchase a Honda part in preference to the genuine Mercedes Benz item.  This washer is the standard CDI injector seal used on all modern Honda 2.2 litre diesel engines (More info on the Honda seal – here).  I personally have had great success using the Honda part as they seem to be made from a superior material and appear more compressible thus making a better seal against any slight face imperfections.

Sprinter Injector Seal

Sprinter Injector Seal

If your 6mm torx clamp bolt came away cleanly and without damage, discard the old one and purchase a new item from Mercedes.  This part is a stretch type bolt and once used must be replaced.  The bolt hole has to be spotless and clean and have no debris or metal swarf at its base.  Any solids in the hole will be compressed at the base of the drilling when the bolt is tightened and can cause cracking or worse – bursting through into the water jacket of the cylinder head (really easily done) so clean that hole with an air-line or blow gun until you are sure it’s clear.

Sprinter Diesel Injector

Sprinter Diesel Injector

Replace the injector with its new copper sealing washer, using a slight smearing of high temperature ceramic grease on the body sides and position it correctly with regard the electrical connector, replace the clamp and clamp bolt, fit the new clamp bolt and torque it down to 7Nm then 90 degrees turn to finish – NO MORE.

While the actual MB recommended spec for tightening the hold down clamp bolt is 7Nm plus 90 degrees, plus 90 degrees – 7Nm plus 90 degrees will provide a safer torque to yield on a new bolt in an old head.
The Honda washers are ‘softer’ (unmeasured science, but you can tell) and I have always consciously never bothered with the extra and last 90 degrees crank. Never had any trouble.

Each 90 degree rotation past 7 Nm with a new clamp bolt and clean hole results in a further 0.3mm stretch bolt yield, so my view has always been – softer composition, less crush and a little less beads of sweat on the final swing of the wrench! (Those threads are a weakness) Correct spec by the book with thinner less malleable copper MB washers is 7Nm +90 +90.

The full factual reference write up is here, I always have agreed with the final conclusion that offers this advice and hence never added the increased stress of the final 90 degrees. Obviously the final choice of wether to use the factory torque spec or the modified spec is entirely your choice, but the tests carried out below are well worth a read before you make that decision.

Technical Reference Article:-

Tightening the fresh hold down bolt and seal ring will produce the same clamping force (defined by seal ring crush thickness) regardless of which of the 2 torque specs are used.

The desired residual bolt stress (to achieve essentially infinite cyclical fatigue life) is achieved by both specs but the 2X 90 spec does allow for less care and precision during the tightening procedure. Torque spec #1 (62in/lbs +90) is certainly less risky if contamination may be lurking at the bottom of the very deep blind bolt hole. I suspect it is also somewhat less risky if the aluminum threads are not in ‘as new’ condition.

“Here at the Global Sprinter Research Center I am always eager to investigate Sprinter related technical issues.

Group members have noticed that Mercedes Benz has a published torque spec for the injector hold down bolts that seemingly differs significantly from the long standing DC published specs as shown in DC workshop manuals as well as on the instruction sheets that DC at one time included with replacement injectors. The extended threaded shank length, 85.83mm long, 6.0mm dia., 8.8 grade, factory hold down bolt, hold down pawl and injector seal ring are identical part numbers for both the 5 cyl. and 6 cyl. engines.

Using my ‘test’ 647 Sprinter cylinder head, which is permanently mounted to one of my work benches, I have recently performed tests related to hold down bolt torque. This dedicated ‘test’ cyl head has been quite useful in my repair tooling fabrication.

As many of you know I have developed in-house tools and fixtures for removal of broken hold down bolts, repair to stronger than new stripped hold down threads, and various custom black death repair tools for my in-house use. This test head features my custom carbon steel hold down threads making it ideal for these hold down bolt torque experiments because data is not compromised by any aluminum thread deformation or failure.

After careful measuring of bolt length (before and after torquing) and injector seat seal thickness to 0.01mm tolerance, and using a calibrated Snap-on electronic 1/4 inch drive torque wrench set to display in/lbs and accurate to 0.1 in/lbs, I have the following observations to report:

TRIAL 1– A fresh, factory hold down bolt torqued to 62 in/lbs (approx 7 Nm) and then an additional 90 degrees, results in 0.08mm crush of a fresh factory seal ring.

The Sprinter’s copper seat seal ring features a double convex cross section and the clamping force induced ‘crush’ creates narrow sealing flats on each side of the ring.

Monitoring the bolt torque during the 90 degree rotation reveals a peak of 180-190 in/lbs before full 90 degrees is achieved and remains at this level all the way to 90 degrees. This peak/plateau signals bolt yield has occurred.

TRIAL 2– A new seal ring and a fresh, factory hold down bolt torqued to 62 in/lbs. (approx. 7Nm) and then an additional 90 degrees X2 (FULL 180 degrees), results in the same 0.08mm crush of the seal ring as well as a steady 180-190 in/lbs torque reading during angle tightening.

Being a stretch to yield, non-reuse, bolt it was not surprising to see permanent elongation. Elongation was approx. 0.30mm for each increment of 90 degrees of tightening rotation (after the 62 in/lb initial torque).

TRIAL 3-A fresh hold down bolt tightened to failure. The bolt tolerated several additional 90 degree sequences PAST the initial 62 in/lbs and 2×90 degrees.

It has previously been reported that fresh hold down bolts have failed when several group members had torqued to 62 in/lbs and then 180 degrees (mistaking 1/2 turn for 90 degrees). I now suspect this occurred because of bolt bottoming in the base of the blind bore. Bottoming can occur because of debris at bottom of the blind hole.


Tightening the fresh hold down bolt and seal ring will produce the same clamping force (defined by seal ring crush thickness) regardless of which of the 2 torque specs are used. The desired residual bolt stress (to achieve essentially infinite cyclical fatigue life) is achieved by both specs but the 2X 90 spec does allow for less care and precision during the tightening procedure.

Torque spec #1 (62in/lbs +90) is certainly less risky if contamination may be lurking at the bottom of the very deep blind bolt hole. I suspect it is also somewhat less risky if the aluminum threads are not in ‘as new’ condition.

Be sure you test your cyl head’s bolt hole threads by using a wire brushed used hold down bolt with an indexing paint mark, turning in by hand while counting turns, to assure threads are clean and bore is unobstructed to full depth.  This is especially critical when performing black death surgery.” 

Information source provided with thanks by Andy Bittenbinder 

If you had a problem with the thread you can use this type of kit or as a more desperate measure carefully tap out the hole to 8mm using a long series drill and tap, if you do this you will also have to drill out the clamp bracket to accept the new diameter bolt.  When drilling/tapping take care to not descend deeper in the head than you need to and break into the water jacket.  Sometimes you may find that the previous repairer has broken into the water jacket – add a small amount of silicon gasket compound to the last section of threads of the pin and tighten down in the normal way.  This is not the best way to get out of trouble, but will at least enable you to complete the job.  If you don’t do this and a bolt hole is broken through – you will leak water!!

Now your injector is back together, in the cylinder head and clamped down, reconnect the steel fuel supply hose and electrical connector and build up the inlet manifold and turbo pipework.  Start and test the engine.  The engine should fire after a couple of cranks as no fuel bleeding is necessary.  All should now be well with the repair and you have carried out a major maintenance repair saving you hopefully quite a lump of cash.

More info dealing with the actual removal/installation of the injector and its seal – here

Good luck.

330 thoughts on “Mercedes Diesel Injector Advice – Sprinter and others

  1. Hi Steve,
    I have a 2007 OM 642 in a G Class, 100k miles, full service history, runs fine, but, and only once the engine is up to temperature, the engine makes a fairly loud tapping noise when under load. Taps rise with engine speed.
    The engine is clean and has no apparent leaks from injectors or exhaust parts.
    It has on a couple of occasions started with one cylinder not firing at cold start, turn it off and restart and it’s fine – any ideas ?
    Many thanks…..

    1. Hi Tony,
      Sounds consistent with a faulty injector, if it is overfueling on one cylinder this could be detrimental to the engine if left as piston damage could occur. Best to get this checked out asap as its an expensive engine to repair its internal components.

      Just a couple of other ideas to check before committing to the above, check for delamination of the crank pulley, it has a rubber damper between the inner part and outer, what happens is this begins to break up. As the engine gets warm the rubber softens more and deflection due to auxiliary belt gets worse. The metal pulley clips the crankcase and you get the clicking – this often sounds like a heavy metallic knock. Also check if the noise can be made to change by pressing the brake pedal fully at idle, if so suspect the vacuum pump. If the noise goes/lessens any when press the brake is depressed then look at the vac pump as the cause.

      Hope this helps
      All the best

      1. Thanks Steve, much appreciate your response.
        I’ve just sent you a seperate email to see if i can pop down as I’m just up the road near derby, do you also have a mobile number I can call you on.

        Happy to pay for your time if I can bring the car down to you for a listen.
        Thanks again

  2. Hi Steve
    Found this article really helpful and hope to tackle injector problem next weekend.
    I just wondered if the Vito 109 CDI (2008) was the same procedure especially the Honda Seal?

    Many Thanks


    1. Hi Jeff,
      The short answer is if your injectors look the same then yes. Some later engines had rather different Piezo injectors that look different from the top without the fat solenoid shape on top. I imagine your engine will be the same configuration as the sprinter engine shown in the post, in which case the Honda washer solution is perfect.
      All the best

  3. Hi Steve,
    Great article which will help me greatly with this weekends job of rectifying certainly one chuffing injector on my 270cdi c class. (and its my 10th anniversary no restaurants for me) I have to admit to fitting a new engine management chip to help increase fuel consumption on the old girl, (car not wife!) which worked well to begin with, but after a week or so noticed higher fuel consumption and increase in smoke emissions and on discovery of this blowing injector I assume over fueling. That said there is a lot of the Black Death all around so this may have been going on for a while (my excuse to the goodlady for buying a chip to try and save money on fuel) many thanks once again and wish me luck. Regards Simon

    1. Hi Simon,
      Congratulations, I am a fan of no-frill celebrations. We got married in our dinner hour and both went back to work in the afternoon! With regard the Injector job, I am sure all will go well, what you have to do is take your time, if anything won’t budge don’t force it, ease it off with all the chemicals at your disposal and get the engine really warm before you start – never attempt injector removal with a stoney cold engine if at all possible. S-L-O-W-L-Y does it for everything and you will be fine. Think things through – ’cause and effect’ before leaping in if you face a problem.

      Let me know how you get on….

      All the best

      1. Hi Steve,
        Thanks for the advice injector removed engine and injector all cleaned ready for re-fitting however just a bit more advice please could not locate injector seal but have just re-read this discussion and will try again its there somewhere the washer for the injector clamp and bolt was also missing is this common? and sorry but one more thing painsteakingly took my time to clean the hole where the clamp bolt goes seems ok so I try to re fit old bolt to check threads however its not biting may need more cleaning but just concerned it maybe more serious thanks for your patience.

    1. Hi Simon, the seal should be at the base of the hole in the head where the injector came from. Often it will be blackened and will have to be seen with a torch. Removal is possible often using a round file pushed into the hole, but you may have to make a hook from a welding rod to fish it out. Once removed inspect the seat (aluminium face) for damage. Unless this perfect, refitting with a new seal is a waste of time, it will leak again. Perhaps you could get a long series engineers tap to clean the threads of the hold down bolt. There is no washer on the clamp bolt, it should however have a ball type profile (under the cap head) that sits into a round pocket on the clamp, this allows the correct angle of the bolt to be maintained as the clamp is tightened down.
      Hope this helps
      All the best

      1. Many thanks once again all done needed to do three of them in the end last on needs the silicone gasket sealer but other than that great advice

  4. This is so helpful . I just got a 2006 3500 drw 2.7 inline 5 cyclinder 100k miles, allegedly. Two of the injectors have terrible black death. Hopefully no major engine damage. But well see. The rest of the truck is pretty decent. Ive always wanted a sprinter. Might have overpaid 10k usd.

  5. Dear sir
    Could you please give me the correct torque setting for the diesel injector end cap on a Mercedes E 280 cdi 2008 .I have had the end cap off as to remove the nozzle to clean it with carb cleaner I don’t want to over tighten the cap as I have heard reports of them splitting. Many thanks.
    Regards Geoff.

    1. Hi Geoff,
      I am afraid I do not have this info to hand. I have all my injectors serviced at the local diesel specialist where they can test spray pattern etc. I suggest speaking to a commercial diesel specialist repair shop they should have this info off the top of their head and may even offer to test yours for a few pounds before you build up the engine.
      Hope that helps,
      All the best

  6. steve are an absolute star…just found my 313cdi with black death..readind up on it wsa empowering..first mistake ..the mech did not warm the engine so battled to remove injectors..then tried to rebolt injectors with used having inserts put in with shortened bolts..will insist on Honda seals..he also put additional o ring on injector..are we on the right track..bob moodley ..Durban..south africa

    1. Excellent news Bob.
      Just be sure that when reworking the hold down bolts you re-tap the head and not the rocker cover above as this will not hold the injector correctly. It is a stepped hole, the upper part being clearance through the rocker cover then into the tapped section in the top of the head.
      All the best

      1. Same story here, and this is a job that too many mechanics are unwilling to take on. Maybe I’m over optimistic, or it’s just that this article is so good, that I’m going to do this myself.

        I have a question though. I need only one insert for one injector. Can I install that without removing the rocker cover? Insert is 10mm external diameter, M6 internal, 14mm long, no flange.


  7. Hi Steve
    I have a quick question, would be great if you could help,
    basically I had to remove all the injectors from my 2003 Mercedes c220 w203 to have them checked as I was having some problems which I have resolved, the question I have is do my injectors have to be put back into the engine in a specific order?
    Kind regards jay

    1. Hi Jay,
      Sorry for the late reply.
      The injectors should be put back in the order they were removed if at all possible as each one is coded to the ECU. This optimises the electronic injection pulse to the mechanical fingerprint of the injector for best fuel economy and performance. In reality with higher mile older engines there is little difference to performance or how the engine runs, in later models its critical. 2003 you should be OK – if you wanted to code the injectors, if you have forgotten or did not note the order of removal, it can be done with a STAR diagnostics or compatible diagnostics unit – any good independent could do this for you if you need – note the unique numbers of each injector solenoid before you replace the engine covers, give this list to the garage with the locations and the rest is done through software.

      All the best

  8. Hi Steve.
    Just drilled and tapped out hole to 8mm , was the king of using an ordinary 8m bolt as there is no stretch bolt that size? Would that work ok and if so what should I torque it down to.

    1. Hi Brian,
      Mmm bit of an unknown, using this chart as a good guide

      It looks like between 10 and 15 Nm if you take what the chart says for perfect conditions as a maximum. Thats where I would be. See what you think, take a look at the bottom right of the page.
      All the best

  9. 2005 Sprinter suffered black death. while driving blew oil out the dip stick . . Mechanic replace front two injectors, now engine runs but no power. Took to a second mechanic and the say engine is toast..

    1. Hi Ron,
      If you have huge crank case pressure then the chances are the mechanic is correct. Combustion gasses are being allowed into the crank case at a high rate if there is enough pressure to blow out a dip-stick. There is a chance there has been a damaged injector which in turn has been over fielding and caused some issue to one of the pistons (they get over hot) Unless there is general wear to theengina and all bores are passing gasses to the crank case I cannot think what else it could be.

      Make sure the exhaust system is clear and there is no undue back pressure being caused.

      Hope this helps,
      All the best

  10. Hi Steve, just wondering if you could shed some light on a injector problem.
    Vito 109 popped a injector and started puffing. I took it to my mechanic and he fixed the broken retaining
    bolt and gave the van back. I straight away noticed it puffing black smoke out the exhaust it seems to be
    just one cylinder as there is a slight misfire with the puff of soot. I have taken it back to the mechanic to
    get this fixed now.
    Q: Is there anything the mechanic could of done to cause this problem or more likely to be due to the injector coming lose?
    It is now been back at the mechanics for 2 weeks and he has just told me today that he replaced all injector and there is a misfire, he also saying it’s down on compression 230 psi
    I’m an ex mechanic myself but never worked on diesels, and I’m starting to think something doesn’t sound right.
    The van ran very well before the injector popped…..
    Any advice would be great

    1. Hi Mark,
      Obvious one is: did he use a new copper seal on the injector and reseat the pocket? Often a chuffing injector will cut and scar the alloy face to bottom of the pocket and prevent a good seal even if a new seal is used. Black smoke means unburned fuel so there is a chance compression is down as a result of a poor seal and connected poor incomplete combustion of one pot. (missfire?) Anything less than 340PSI and you have something going on. Either that seal is not doing its job or there some other connected issue, bore wear or otherwise. Strange as it was not an issue while it was chuffing, this makes me wonder if its the seal on the injector. It would be important to look and see if the cooling system was pressurising as this could indicate a head gasket problem.
      Hope this helps

      1. Thanks for your reply Steve, the mechanic has told me the timing chain has probably jumped a tooth which is causing the low comp and the repair costs are now so high that
        I have decided to scrap it instead. I still feel like they did something wrong and damaged
        my engine but there is no way to prove it.
        Unfortunate because it was running really well before the injector problem, and it’s only done 190,000 km which is low for a 2003 model.
        Thanks again

  11. Steve, Thanks for this writeup. I have a 320 CDI with the same injector leak issues. My manual says to replace the hold down fork as well. I’ve ordered new bolts, but not the hold down forks. Also, a T40 doesn’t seem to fit exactly in those injector hold down bolts. Is it other than T40?

    1. Hi Doug,
      It is T40 inverse Torx. Often the sockets you buy have a deep chamfer before the socket starts, this can mean the bolt does not go into the socket as positively as you would of liked, some sockets are pretty much flush and do fit better. Its down pretty much to what tool you buy but any T40 should do for the very light torques involved in tightening these.
      All the best

  12. Hi Steve, I have a Vito 109 CDI, 57 reg.
    Previously mechanic cheked and told me that 3 injectors are leaking and that best thing is to replace all of them(4). After seing how much would that cost me I’ve continued to drive as it is. At first it didn’t start in the morning and now for the long time it doesn’t start at all(without the spray). Once it starts it’s driving ok…I know I shouldn’t be doing for too long(start with the spray), but I did and time has come to face consequences…Could you give us some advice, please?

    1. Hi JJ,
      I would chip off the coke around the injectors with the engine cold, use a vacuum cleaner to keep it tidy while working. Once clear, warm the engine as best you can by running it, then remove the injectors and replace. They will most likely be well stuck as they have all been leaking for some time, you may need to use a puller. If so budget for new injectors and a good recut of all the seats as often old worn injectors do not go back together well internally. Minimum have them tested by a diesel specialist before refitting.
      Its time to open the wallet!
      Good luck, all the best

      1. Hi Steve, I’ve just done this on my 115 cdi but now found that I cannot start the engine doesn’t fire at all not getting anything fuel to the main injector bar. Any advice. Thanks

      2. Hi Jim
        There will be air in the fuel system and only cranking to the point of exhausting maybe two batteries will sort this. I have had them where I too have thought there is an issue, however keeping going usually results in success. If any of the unions are opened there will be no fuel pressure, it’s a safety failsafe.
        I hope you managed to get it running, sorry its taken a while to get to reply.

  13. Hi guys I have a Vito 115 cdi 2005 I vant to Chenge the injector drone Vito 115 to Vito 111 any one knows because my is gone thanks

    1. Hi there,
      As long as it is the same style (solenoid and not piezo) then you should be OK, as the horsepower difference is mostly due to ECU mapping and injector timing not nozzle size. It would be good to have the injector coded once installed so make a note od all the numbers on the cap before installing and get your dealer to code them into the ECU for that cylinder/injector if required.

      1. Ok thanks because I find very cheap injector $120 Aus like brand new I take off by myself the car runs only 25000

  14. Hello Steve, most excellent and informative service your offering here. Pretty much got this chuffing injector business weighed off to the point I could remedy it in my sleep. I have, unfortunately learned the hard way and made a few schoolboy errors along the way. One of the trickiest gremlins I dealt with on one particular stubborn injector that wouldn’t stop leaking was the small issue of compressed debris at the bottom of the stretch bolt hole/thread which prevented correct clamping of the ‘hold down fork’ and subsequent injector. Using a hss drill bit between my fingers i managed to drill out the crud thus allowing full penetration of the stretch bolt. Currently, I’ve been running my 04 Viano with a rear chuffing injector for a couple of months and it’s just been a case of just getting round to sorting it before the dreaded BD starts to set in. Well, I’ve just stripped it out and notice the screw on end cap on the injector has a crack in it. Now I know this is a fairly common thing and have replaced injectors in the past, begrudgingly. Why is it not possible just to buy the end instead of the whole bloody injector?? Anyway, Steve.. is it possible that the injector is leaking via the cracked end cap as opposed to the seat??

    1. Hi Tony,
      If this is the injector tip you speak of then a diesel factor that refurbishes these units will have access to either used or substituted tips and they will calibrate and test it to the new/replacement installed part. If you mean the union that the fuel rail and piping attaches to then this can replaced non the same way, though if the cast body is cracked its a bin job. The latter would not cause carbonising the former may depending on how bad the fault is.
      Hope that helps

  15. Hi I just want to find out on a mercedes 2.7 diesel where should the sensor gear gab be if piston one is on top…. and then maybe you guys can help out my enjine swing but no diesel is coming from the injectors

    1. Nick,
      The crank sensor is above the starter motor on the bell housing line. If when cranking your tacho needle jumps there is a good chance there is a signal from the TDC sensor. Often having an open diesel line will prevent any diesel being pumped, its a CDI failsafe. The most likely problem for poor starting is either no camshaft / crankshaft synchronisation (you will have an engine fault lamp on dashboard) or that the fuel rail is not allowing starting pressure to be reached. Sometimes caused by fuel regulator O ring failure. See here
      The camshaft sensor is on the valve cover at the rear and often plays up due to extreme environmental conditions over its lifetime, Hot and Cold.
      Any loom electrical problem or disconnection/short to any of the five injectors will prevent the others firing and a non start situation.
      Hope this helps

      1. check your Camshaft Hall sensor which is on the back of the camshaft cover
        left hand side you will see it mine was doing the same thing wouldn’t start because of the extreme heat condition under the cover the plastic cap cooked/melted
        i suggest you don’t refit the top cover as this will allow more cooling to take place it’s only there to look neat

  16. Hello,

    Thanks for the information. I have a 2005 E320 CDI with the black death issue and we determined it was injectors number 1 and 4. One came out fairly easy with a slide hammer (in the grove of the hold down) however 4 was very difficult but we were able to get it out. The issue is that the bottom piece of the injector which mates against the copper is cracked about an inch up from the bottom. Will the injectors for the 2.7L 5 cylinder work in the 3.2L 6 cylinder engine? They are significantly less expensive and more readily available. Thanks for your help,


    1. Mmmm thats quite a question Matthew
      To be sure you would need to take the numbers from the original injectors and the numbers from the proposed injectors and cross reference them on a Delphi parts catalogue (often Online). You will then be able to see what type of solenoid injector is common to engine ranges in the MB line (some are Piezo and not interchangeable but do look physically different). It may be worth approaching a diesel specialist who would probably offer the information easily off the top of his head. Quite possibly he would be able to rebuild you own injectors into new bodies and test them as 100 percent for a big saving on new and in some cases second hand.
      Hope that helps you a little
      All the best

  17. Hi Steve

    Really helpful and comprehensive information here!! I could really do with some more advice though. I started to remove an injector on my 2.7 crd and I’ve got coolant coming from the bolthole so I’m assuming a previous repair burst the gasket below. My question is, will this be OK if I use some gasket silicone when putting in the new bolt or do I need to take more serious measures? Thanks in advance for your much anticipated reply.

    1. Hi Allen,
      Absolutley yes!! As long as you have good thread condition and the hole is capable of taking a new hold down bolt, just add a small smear of silicone gasket compound to the bolt and torque as outlined in my text (7Nm and just the one 90 degrees – see my reasoning for this in the write up if in doubt)

      All the best and good luck!

  18. I have an 05 sprinter 2500 van with this in line 5, I’m getting fuel pressure all the way until the black solenoid but no fuel comes out the output of the high compression pump to go to the fuel rail. Would there be anything else to cause the fuel to stop at that solenoid or is it because the solenoid is bad?

    1. Kyle,
      The rail pressure will not build with the high side cracked open. No or little sealing will result in the pump not pumping fuel – its designed that way for safety reasons. What does live data say the fuel rail pressure is at crank it should be almost 300 bar for a start condition, if substantially less then it simply won’t start. It could be the O ring on the fuel pressure regulator or a bypassing injector that is leaking off rail pressure and preventing useable starting pressures to be reached. Do a leak off test to prove/disprove this.
      All the best

  19. Hi Steve,

    I have a problem with my 2009 311 sprinter 100k miles on the clock. I have noticed the oil level has been increasing on the dip stick and then the high oil light came on intermittently. The light seemed to come on more when the speed was higher, probably 50mph or more. I drained around 750ml oil from the sump and the light has went out.

    I have checked the coolant level and oil for cylinder head damage and appears to be fine. I was thinking it might be diesel and oil contamination. Is it possible for the DPF to contaminate the oil with diesel? I had the van idling for a while and without moving, i was doing some work to the inside (campervan). Maybe around 4/5 hours in total but not continuously and over several days. Would this effect the DPF if it was not getting warm enough to burn off the diesel?

    I was also thinking it could be a fuel injector. The van starts and drives okay with no bad smoking issues and nothing obvious with any engine noises, sounds fairly normal. The other thing to note is the sender unit is not corresponding to the fuel tank gauge, it is under reading by approximately one quarter.

    Thanks for any help. It is much appreciated!


    1. James,
      If the DPF is clogged it could start to push crank case pressures up, most probable is an over fuelling injector that is causing wash down of fuel into the crank case, exacerbated by higher than reasonable exhaust back pressures. A leak down test on the injectors could help to highlight any issues.
      All the best

      1. Hi Steve
        This is not related to the post.
        I have a Vito CD112 2Litre TD 2000 Year of build
        I have lost 4th gear or shall I say , when in drive it stays in low gear, and won’t roll on through the gears.
        If I select 3rd gear it will roll from 1st ,2nd and third. Sometime at cruise I may select drive and think I/m getting 4th, but as soon as I slow it will get stuck in low again.
        Are there some basic, things I should look at sensors etc which could attribute to this error?


      2. Hi Steve I have 08 E320 Bluetec and oil level is very high (3″ pass the high mark). It runs ok, what could be the issue? Thx ed

      3. Hi Ed if there is no water in the oil then it must be being thinned with diesel. This is most probably caused by a faulty injector over fuelling and washing past the piston rings, a faulty fuel pump seal causing unseen diesel escape from the rear rotor seal into the block or just plain old overfilling. Suck out the oil with a oil removal pump to the correct level and monitor the situation. Meantime get an injector leak off test done, a badly overfuelling injector will in time cause damage to the piston and bore.

    1. Mike,
      There are many expensive options available for pullers but if you are just doing the one and want a cheap solution you can use one of these

      Just make sure you keep the parts you have to remove in order and as clean as is humanly possible.


      1. Great Advice thank you the Honda washers are noticeably better than the mb washers and thanks for the puller link one of mine was solid three easy now I have two glow plugs seized so I’m not done yet!
        thanks again

  20. Hi New to this.
    I have just been stitched up and have bought a c class 220 CDI , had a problem with large missfire when cold and very big fume problem in the cabin took it in to have exhaust checked, the tech said i know what’s wrong by the sound of the engine, he removed the plastic top cover and showed me the fumes being pumped out past the faulty injector!
    They do not do deisel, so i thought i will fix it myself i have a engineering background,
    How difficult can it be? Wish i had looked here before i got into it!
    Fitted new seal after recutting seat, during refitting i broke the bolt,
    Checked at what depth it broke at, about 30 mm had broken off
    Did not bother to extract, instead i retapped for hellicoil,
    Look’s like just rethreading the first 20 mm will not work as that’s only rocker cover,
    Anybody had any success removing a broken injector clamp bolt?
    Great site.

    1. Drilling with tipped long series drills is the only way, slowly and with careful progress. There are companies who can spark erode the sheared stud in place but usually price for the specialist job outweighs the economics.

  21. Hi steve,

    For the sprinter injector, the top part where the electrical socket sits, i confirmed from testing it has short circuited.
    Does this mean the nozzle is a complete loss or i can purchase just the top electrical socket part of the injector.?

    Pls help this sprinter is also an ambulance

    1. Hi Gulrez, better off with a complete new injector (or used) the solenoid had calibrated packing shims to the pintle and I would imagine would not be calibrated correctly if just the solenoid cap was switched.
      All the best

  22. Very helpful article. I just finshed all six injector removal, clean and new copper seal and oring on 08 GL320 CDI. I had black death on one cylinder and began to spew diesel while running. all fixed now. The thing I would like to reiterate to all is to get engine hot. It makes everything come apart easy. (I ran mine for 45minutes) That even made the fuel return line clips easy to come off by hand. I was fighting with them after 15 minutes of engine run and they were easy at 45minutes) plus the injectors come out easy by hand. I ordered the kit with 6 new return line orings, bolts and copper gaskets and job done in one day. cleaned injectors and injector seats as descibed but used a 1/4 drive extension with 200 sand paper on end, then taped, to clean copper gasket seat. again get engine hot. (torqued at 7nm plus 90 deg as specified) I changed air filters, fuel filter, and turbo inlet seals while all apart, also put in oil catch can. I suggest diesel injector line sockets from AB tools 17mm, made things easy. Thank you all for the details to make a hard job easy. Emory

  23. I wish I had read this before performing my maintenance.
    ***Buy New hold down bolts

    I tapped in to deep, right into the waterjacket, hold down bolt is sitting 1″ over hold down bracket used washers ( temp fix) since I dont have a long enough tap set, managed to tap out 2″ but still need to go deeper, any suggestion?
    Very nice write up. thank you

  24. Hi Steve can I just say it takes time to read these and get back to people with advice.. For this I would like thank you for all your time and effort! You have helped us all no end!
    My question is on my recent purchase of a CLS 320 CDI auto 2008..
    I have fitted a new Bosch Injector to one that was chuffing and had a lot of carbon built up around it..
    I gave my vin number when I ordered it and was told this was the correct injector for the car.. I’ve now fitted it and everything seems fine. My only worry is a comment somebody made with regarding mapping the Injector to the Ecu? I haven’t done this and it runs fine? I just wanted reassuring that was all? I too used the Honder copper washer and followed all your advice on here!

    Thanks Steve

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