W210 E220 cdi difficult to start

[robertjary]

The problem started on Saturday, a very hot day, when I tried to start my car. The engine turned over but refused to start. Releasing the key did not stop the starter motor running. Only turning the key all the way back stopped the starter motor. On the second attempt, the engine started to run for a brief moment and I released the ignition key. However, the starter motor continued to run but the engine was not firing. Again turning the key back stopped the starter motor running. On the third attempt, the engine started as one would expect. Yesterday morning I had the same problem starting the car. This morning the car refused to start until about the 10th attempt. The problem occurs when the engine is cold or has been left a while. Stopping and restarting appears to be OK. This feels like an electrical problem, possible a relay.

The car has a full service history and the current mileage is 280k. Any ideas or hints where I shoul look first, before I call Mobilo Life?

Many thanks, Robert

 

[nujon]

If the car was perfectly OK before Saturday and if there is no evident fuel leakage when cranking the engine - and if the car has a mechanical lift pump at the front of the engine (rather than an electric lift pump in the tank) - the usual cause is air being drawn into the fuel line to the lift pump via the fuel supply line sections - the suspects are:-

1. the rubber hose from the chassis to the pre-heater
2. the rubber hose from the pre-heater to the filter
3. the plastic hose from the filter to the lift-pump inlet

Change all three (using MB clips on the rubber hoses - not jubilees) - only about £30 from MB the lot

By the way, the continuing cranking for some seconds on releasing the key is normal if the engine does not start - wait 30 seconds between attempts to avoid burning the s/motor

 

[BlackC55]

If the car was perfectly OK before Saturday and if there is no evident fuel leakage when cranking the engine - and if the car has a mechanical lift pump at the front of the engine (rather than an electric lift pump in the tank) - the usual cause is air being drawn into the fuel line to the lift pump via the fuel supply line sections - the suspects are:-

1. the rubber hose from the chassis to the pre-heater
2. the rubber hose from the pre-heater to the filter
3. the plastic hose from the filter to the lift-pump inlet

Change all three (using MB clips on the rubber hoses - not jubilees) - only about £30 from MB the lot

By the way, the continuing cranking for some seconds on releasing the key is normal if the engine does not start - wait 30 seconds between attempts to avoid burning the s/motor

It does not have rubber hoses. Just plastic. I think you maybe refering to a different engine.

I suspect an injector, fuel rail sensor or air in the fuel system issue.

Get a "leak off" test done first to see if the injectors are ok. Get the fault codes read too.

 

[robertjary]

Hello BlackC55,

Called Mobilo Life, ran leak off test - all ok. Then he read out fault codes which showed a major fault on the camshaft sensor, 'camshaft frequency too high'. Cleared fault codes, reran diagnostics and cranked the engine. The camshaft sensor fault again appeared. But no camshaft sensor in Mobilo Life R class. However, the car will fire after 5 or so attempts. I'll get a new sensor on Wednesday.

Many thanks for your help.

Regards, Robert

 

[allias]

Was the camshaft sensor solution for this fault? Is your OK? Because I got the same problem on mine.

 

[robertjary]

Hello,

Yes it was the camshaft sensor, although the MobiloLife man suggested that the crankshaft sensor was generally more likely to be the culprit - he's replaced more crankshaft sensors than camshaft sensors.

Regards, Robert