my mercedes is having starting problems? it will start the first time. I can drive a few miles down the road stop at the shops, get back in the car and it will not start again. If I wait 10 minutes it will start. When it will not start, i turn the key and the car turns over no problem but it keeps turning ver even though I have let go of the ignition key. I have had the starter motor replaced but still having the same problem. can anybody help please. I have been to Merceds and they have put the car on the computer but no error messages

 

What you describe is normal..........looks like you replaced the starter motor for no reason!..........ML's have what's called an 'Autostart' feature, you simply twist the key to the start position and let then immediately let go, the starter motor then remains engaged and cranks until the engine starts (it cranks for a max of 30 seconds).

The intermittent starting, as you describe,could be caused by a faulty crankshaft position sensor (cps) about £80 for the part and easy diy job.

 

how easy, and where would I find this sensor?

 

Had the same problem - computor also showed no fault. Changed the Cam shaft and Crank shaft sensors - no result. Then I changed the diesel presure control valve on the common rail - sitting against the cabin on the end of the common rail. All problems were solved. Seems if there was a very small piece of silicon stuck on the plunger - must have got into the diesels sytem - possibly came loose from the diesel filter.

There is a easy way to find out where the problem is. When the car is hot and the problem persist, you pour out about 10 litres of water on the supect part and will suddenly start.