Originally Posted by Dee Cee
I have a 2003 640 adv and it is getting harder to start...
Is the auto deco prone to wear in these things and if so, are they repairable, or do I have to replace the whole camshaft to get the needed part. .
The auto decomp mechanism on the cam is an extra lobe that runs on a couple of pins on the LH end of the cam:
One of these pins is prone to wear but it usually takes a few km, the above one had done 95K km. I reckon a good engineering/machining shop could probably extract & replace the pin but a new cam might be cheaper & comes with a new decomp lobe too.
If you've got a starter clutch problem you'll have a whizzy/grindy noise when trying to start, as opposed to a worn auto decomp which makes it seem like the battery is dying.