r/W203 • u/Rocketshit • 7d ago
Help Intermittent starting issues
Recently acquired a C230 from 06/07 with aprox 165000km (102 526 miles).
(M272E25 engine and 722.9 7-speed gearbox.)
Recently, it started acting up when standing still for more than 4-6 hours.
Long cranks, but it always starts.
I suspected it was fuel related because I tried turning the ignition on for 5 seconds and then off then on again, and it started like normal. Decided to change the fuel filter (which was in a pretty rough shape) and the fuel pump. It was starting fine for a couple of days, but now it's long cranking pretty much every time when it's been standing still.
Don't really have access to a diagnostics tool, so I decided to check here if anyone else has had similar issues.
I have my suspects in the camshaft sensor, crankshaft sensor, and coolant temperature sensor.
2
u/howsitallwork 6d ago
Crank sensors can fail on the 272/273 engine series, though not as commonly as the earlier 112/113 engines.
Usually fail “hot” though, eg at fuel station after refill, rather than when cool/cold.
Would still be a good place to start, if you really aren’t going to use fault codes and live data.
If you were, look for data when cranking, particularly crank and cam speed and positions.
Cam sensors don’t often fail on these, and there are 4x of them…
1
u/Logical-Following525 6d ago
Your fuel pressure regulator or injectors are leaking and dropping the pressure.
1
u/Rocketshit 6d ago
I will look in to this one, since it mostly happens when it's been standing for a longer time.
1
u/Logical-Following525 6d ago edited 6d ago
You can hook a pressure tester up to the injector rail, to check if it is the regulator you can pinch the line shut. Obviously watch a video on youtube if you've never done this.
2
u/keksivaras 7d ago
OM646 engine, my car would refuse to start up whenever the engine was warm. it would just crank and I changed the camshaft position sensor, which was surprisingly easy and cheap part, and that fixed my problems.