Re: Merc 300 assistance please

[chinewalker]

1) Uses a 12V battery for starting.
2) I’d invest in the OEM service manual (part number C-90-25500). Will cover the water pump, and much more. Will pay for itself in saved frustration.
3) Depending on what it’s doing, it may have been installed incorrectly after a previous water pump service – not uncommon for them to jump into forward with the lower unit off, then get installed without properly aligning the shift rods (upper and lower). A bit tricky, but not difficult. Again, manual is helpful here, too.