ML 270 cdi 2002 - starting problems

[tommy94y]

I have a 2002 ML 270 CDI auto with 113,000 on the clock.
Over the last 12 months, a problem has occurred where from cold it turns over approx 10 times before it fires and even worse when warm.
Last winter it let me down twice in the freezing weather and wouldn’t fire at all.
I’ve replaced the battery and have recently replaced the fuel filter. This seemed to improve things and the car appeared to be back to normal. However, as the fuel filter wasn’t a genuine one, I replaced it again with a Merc one.
It’s now taking about 10 turnovers before firing in the morning when cold and when warm it’s even worse.
With the cold weather coming up I’ve lost confidence in the car as I think it’s going to let me down again.
Apart from this, the car is fine.
Any advice or comments much appreciated.
Tom

 

[Alex Crow]

The 2x most likely scenarios are air in the fuel system, and excessive injector leakoff.

If it were air getting in the fuel system we would expect it to be better when warm, and worse on the first start of the day.
Another thing to note, it would start better if parked facing down a steepish incline, and start worse if parked facing up it.

With excessive injector leakoff the starting would likely always be slow, even if stopped and then immediately started again.

The checks - look for air in the clear fuel pipes when starting and running, and perform an injector leakoff tests.

 

[Vlad]

Sounds like Injector leak off to me.....just had a similar problem on a non MB vehicle with the symptoms you describe and one of the injectors was leaking back badly. Had it refurbed and its now an instant starter.

 

[tommy94y]

Thanks!

Thanks to both of you for your advice. On this, took car to local Mercedes specialist who confirmed you're both right on this - car now booked in for work next week.

Appreciate your help.

Many thanks
Tom