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W203 C270CDI Starting Problem

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by renrutp76, Dec 5, 2012.

  1. renrutp76

    renrutp76 Senior Member

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    X218/2014/CLS250CDI_W211/2005/E500 Avantgarde
    Hi,

    Recently my C270 CDI estate developed a starting problem. Approx 4 months ago I replaced the fuel filter, and the fuel line between filter and HP pump due to brittle retaining clips. All seemed to be going well, up until a couple of weeks ago when the morning temperatures started to dip below 3-4 DegC. on the first few occasions, it required quite a lot of cranking to fire 20 seconds (ish). After a couple of days, I was running the battery flat trying. By lunchtime, and several attempts later once the weather warmed up a bit it would eventually fire. If I ran in the morning/afternoon, it would start again in the evening albeit not instantly. However if left overnight, it would not start in the morning.

    I have checked all 5 glow plugs and the glow plug relay. I have taken it to my local garage and left it overnight for him, and he reported back low fuel pressure on start up. His diagnosis is that the fuel lift pump in the tank has failed, Merc want £450+vat for a new "improved unit" complete with new senders.

    I was under the impression that the lift pump only transferred diesel from the passenger side "return" tank to the drivers side "delivery" tank, so how would this affect fuel pressure? The car runs fine once started.:confused:

    Any help would be greatly appreciated.
     
  2. OP
    renrutp76

    renrutp76 Senior Member

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    Just to add, last night after picking my car up, I filled the tank to the top. This morning it started fine!

    Does this still point to the lift pump?
     
  3. turbopete

    turbopete Senior Member

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    i would say that either you have an air leak (probably o rings, theres lots about them on here) or the pump between the 2 sides of the tank has failed. when you were having problems, was the tank down to approx 1/4 on the guage? if so, its probably the latter.
     
  4. OP
    renrutp76

    renrutp76 Senior Member

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    X218/2014/CLS250CDI_W211/2005/E500 Avantgarde
    Hi Pete,

    Yes the tank was just on the reserve, however it has now been filled, and is still suffering:(
     
  5. Steve@Avantgarde

    Steve@Avantgarde Forum Supporter Authorised Forum Supporter

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    C220CDI AMG Line Premium, SLR McLaren Roadster, SL55 & C32AMG
    Air is getting into the diesel system somewhere, the culprit is usually the Y pipe that goes from the lift to the high pressure pump and has a non return valve on it. Also check the HPP for leaks.

    If that looks ok then check the injectors for leak off.

    The lift pump isnt the problem and rarely if ever fail.
     
  6. OP
    renrutp76

    renrutp76 Senior Member

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    X218/2014/CLS250CDI_W211/2005/E500 Avantgarde
    Just to update, things have gone from bad to worse. after 5-6 weeks of easy start, 4 days ago my car refused to start even with easy start:(. I have now spent the last three days in sub zero temperatures and snow with a neighbour trying to diagnose the problem. As a side issue, prior to the car failing, fumes were being draw into the cabin when at a standstill, it was found that injector 5 was passing. I bought a copper washer and stretch bolt from MB, and borrowed an injector pulling kit from my local garage (as they couldn't look at it for a week). I removed and cleaned the injector (lots of back gunk), and replaced the copper washer. The car eventually started after some easy start, but when I sprayed WD40 around the injector to check the seal, it ran past 4 and 3 and highlighted that they were passing. So I thought while I had the kit, I may as well replace the others. 8 hours later, all cleaned and replaced, car then refused to start, easy start only succeeded in bringing it to life momentarily. The diagnosis was still low fuel pressure. The next day, I replaced the fuel line from filter to LP pump, fuel line from LP pump to HP pump (which crumbled as I removed it) still no good.
    I know from when I was re-fitting the injectors that fuel was being delivered, however when I replaced the filter the next day, the fuel line on the inlet side was empty, and subsequent attempts to crack injector fittings resulted in no fuel. I filled a jerry can with diesel, and tried to draw by disconnecting the filter to pump hose and connecting a plastic hose, but no fuel was drawn from the can. My diagnosis is the LP pump, but do these gradually fail? This may be another problem I have inadvertently created by excessive cranking.

    I would like to perform a leak back test on the injectors, but haven't got round to it yet. I have 5 graduated lab flasks, but have not yet found any suitable tubing to attach to the spill return. can this test be performed whilst cranking, or only with the engine running?

    Please help if you have anything to add.....
     
  7. mersum1es

    mersum1es Senior Member

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    W212/-09/350CDI, W219/-07/320CDI, EX:W220/-01/320CDI, EX:W211/-04/320CDI, EX:W210/-01/270CDI
  8. OP
    renrutp76

    renrutp76 Senior Member

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    X218/2014/CLS250CDI_W211/2005/E500 Avantgarde
    just to update, all plastic fuel lines replaced, with the exception of HP pump to common rail (dealer didn't have one in stock). Fuel pressure regulator seals also replaced, but still no start. suspected injectors 3 or 4 passing, so made a blanking washer, and blanked off injector 3. after 3 cranks, it fired, albeit sounding like a bag of spanners. I will order a new injector, and post the results.
     
  9. OP
    renrutp76

    renrutp76 Senior Member

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    C270 Injectors Continued

    Further update, deciding whether or not to bite the bullet and order a few injectors. As previously mentioned the car ran until I removed injectors 3&4. So I took the heads of each of these injectors, and low and behold in injector 4 there was a spacer and a spring, and injector 3, just a spring:confused:.I had a hunt round but couldn't find one, nor could I find any mention of said spacer on google. My only option was to make one from a circuit board spacer, the dimensions were 5.2mm diameter, 1.7mm thick, hole diameter was 3.2mm. Three hours later with washer fitted, still the same:cry:. Next I made a leak off test kit, and ran the car at idle for 1min with a rev to 3000rpm for the last 2 seconds, results were, cylinder 1 12ml, cylinder 2 12ml, cylinder 3 23ml, cylinder 4 8ml, and cylinder 5 12ml. Money is tight and I need her back on the road, so do I replace 3 (leak off too much), or 4 (leak off too little)? It still has a bad misfire, i think caused by bad spray pattern which at idle speed feels like the engine will fall out of the bottom!
     
  10. mersum1es

    mersum1es Senior Member

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    Your Mercedes:
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    Too small leak is not problem (if it leaks), upper limit is 20ml/min. If your injectors has been 'tuned up', there is reason for uneven run...
    Here are good pictures of injector parts (and some discussion in Finnish how to repair internal leak DIY :cool: )
     
  11. OP
    renrutp76

    renrutp76 Senior Member

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    Final Update

    Replaced injectors 3&4, runs much better now, I will run another leak off test at the weekend. Quite a bit of smoke under acceleration, how important is coding?
     
  12. mersum1es

    mersum1es Senior Member

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    W212/-09/350CDI, W219/-07/320CDI, EX:W220/-01/320CDI, EX:W211/-04/320CDI, EX:W210/-01/270CDI
    My previous message missed the link :Oops:
    http://mersuforum.net/forum/viewtopic.php?f=2&t=83970

    I believe your injectors does not need coding... (is there circled single number stamped on the injector?). Smoke may be due to long insufficient burning of the faulty injector cylinder, otherwise its usually turbo issue (if the smoke is black) and smoking is not decreased after several accelerations...
     
  13. OP
    renrutp76

    renrutp76 Senior Member

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    Thanks for the info mersum1es. Injectors 2,3,4, & 5, were number 2 with injector 1 number 3. Injector 3 has now got a number 1...?
     
  14. mersum1es

    mersum1es Senior Member

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    OK, in that case that should be changed to ECU too. Makes some difference but nothing drastic...
     

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