OM648 W211 - Does Crank but no Start - Diagnostic logic check

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Active Member
Aug 31, 2011
W211 E320cdi 2003/ C218 CLS350cdi 2012
Hi, sorry for the long post. I've had this 2003 W211 E320CDI for over 10 years now, and it currently has around 253k on the clock. It has been relegated to being a spare car but is still in regular use a few times a week.

Yesterday my wife had been driving it with multiple stops and restarts with no issue until later in the day when it refused to restart. It cranked but no joy, not even a splutter. I had an icarsoft in the boot and looking for fault codes nothing was present (expecting crank sensor maybe). I called recovery and it started almost immediately with a squirt of easy start. The mechanic suggested it could be a clogged fuel filter. Turning it off at that point and trying to restart resulted in another no-start. A squirt of easy start and off it went again. At this point I drove it the 8 miles or so home without issue. There is about 30 litres in the tank, corroborated by fuel gauge, icarsoft values and based on mileage since last fuel up.

Today I've tried to get to the bottom of it.

  1. Using the icarsoft in the 'cranks won't start' section with the ignition on there was zero bar pressure.
  2. On cranking it went up to 40-50 bar, not enough to allow a start condition.
  3. I bought and fitted a new filter (and some easy start), and while changing it turned on the ignition to confirm operation of the tank lift pump. I have no means of measuring the pressure but got a healthy soaking in diesel.
  4. Plumbed in the new filter and no change even after a number of purge cycles. 50bar or so on cranking, no start.
  5. I squirted some easy start into the intake and as the night before it fired into life. icarsoft shows 350-400 bar which I believe is normal.
  6. I then ran a leak off test, clamping off the return line that goes back to the rail. Just cranking resulted in some diesel flowing from injector 1.
  7. I repeated the leak off test following a squirt of easy start and when running there was increased flow on injector 1, and a very small amount on injector 6. See pic below.
leakoff 18-11-23.jpg

Based on the above I think I have a faulty No. 1 injector that is leaking off causing an inability to get to the required starting pressure. Is this logic sound or is there anything else I should check?

The injectors in the car are around 50k old. Proper Bosch centre refurbs. What caused me to replace them last time was missing/uneven idle, with 2 or 3 failing a STAR test. When running the idle seems fine, plenty of power, no smoke etc. The other day on cold start it did sound a bit rattly. My initial thought was timing chain or tensioner finally starting to wear but no I wonder if the injector had dumped fuel into that cylinder.

Any help or thoughts welcome. Thanks.
Is the engine management light on have you checked simple things
Airflow metre / egr not stuck closed as if that’s happening can cause a bit of engine rattling when running.
Just a thought.
Injector ordered, will report back once fitted. Thanks all.
I replaced the injector earlier today and all seems back to normal, including a cold start after 8 hours. Thanks to all who contributed.
I replaced the injector earlier today and all seems back to normal, including a cold start after 8 hours. Thanks to all who contributed.
Good logical diagnosis 👍👍

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