Change the oil and coolant
before getting started.
Change the oil filter
, impeller, and zinc if there is one. Pull the heat tube and check for clogs, check all the seals
on the cooling
system. Make sure the raw water thru hull
operates. Check the filter basket and make sure it is clean. If the boat has an antisiphon valve make sure it isn't clogged. Once the motor
fires make sure a good stream of water is coming out of the exhaust.
Drain the muffler
if it has water in it. Make sure there is no valve or clog in the exhaust line. Make sure the pipe before the water injection is wrapped so you don't burn yourself.
Check all the motor
mounts. If they've had diesel on them they'll be corroded rubber by now. Check the bolts and make sure nothing is snapped. If you fire the motor and experience high amounts of vibration you'll want to start looking here.
Check the fuel filters AND THE FUEL TANK
if the fuel has been sitting it may have growth in it. Make sure the on engine filter is clean along with any others. Make sure the fuel you're feeding the motor is clean. Bleed the system according to the manufacturer.
Make sure the battery
is charged and the connections between it and the starter are good. Make sure the stop button works and if not make sure you know where the manual kill lever is. Make sure the alternator
is connected and be sure where the battery
switch should be while using the engine.
Make sure your engine throttle Morse control level is still connected correctly and the throttle isn't rusted or stuck.
If the engine has glow plugs, make sure they work. Don't power them over the recommended intervals to avoid burn out. Also don't run the starter over the recommended interval if the motor isn't initially firing, you don't want to burn it out.
Not as bad as it sounds, just take your time and check it all out.