Vito OM651 Alternator

[Kev555]

While I was fixing other things on the van over weekend I decided to try and sort out the last fault code thats been in the van from purchase 18 months ago. Its a communication fault between the starter and Alternator, OBD code is U0120. disconnected the loom running from fuse/ECU box to alternator and starter. I found no visual faults and all ends of the cables were clean and seemed to be making good connections. I disconnected the alternator last thing this eve to leave it with an autospark to be tested but for the life of me could I find a way to get it out. REALLY MERCEDES, were you that short sighted when designing the vito? After looking at the possibilitys of removing the engine mount or the radiator and possibly front of van I called it a day and thought id ask the experts on here in case ive missed an easy way out or something else?

 

[Kev555]

Anybody know the common cause of this fault? I have read different things on net but info is scarce on this topic, some blame loom some blame alternator voltage regulator. Dont want to make work for myself tomorrow eve if possible. Alternator is working fine and from memory its was pumping out about 14.5 volts when I tested it at the battery

 

[Kev555]

Got Alternator out, studied it for a minute this eve and figured the turbo was the handiest disconnect plus would make it handy for reinstalling alternator.
PS: just a wee note in case anybody else follows this path, make sure your exhaust is hot before you start as it will help loosen the three bolts that hold turbo to exhaust manifold as I had to use a torch to heat mine up this eve as van is non runner atm.

 

[Kev555]

OM651.940 engine part number of turbo to manifold gasket needed for reinstalling turbo is A6510960480 (£8.50 for MB genuine on E-bay) you will also need 2 x 10mm internal diameter copper washers for the turbo oil feed pipe. I just used gasket sealer on the return oil pipe old metal gasket as its a non pressure return. Couldn't source a turbo to exhaust sealing ring handy but old one resealed ok.

 

[Kev555]

I should have added above that the regulator on the alternator was suffering from water ingress as with a lot of bosch alternators according to the autospark. It was £50 for regulator and testing and fault code cleared. In hindsight there was a possibility of changing it while attached to the vehicle if id known exactly what the fault was?