I had a new Merc 4.3, shipped from the states, when I bought my boat - the boat didn’t have an engine when I bought it, but it was the perfect boat for us.
There is a running in schedule for the engine and it should be in your Operating & Maintenance Manual under Getting Started. If you can’t find it mine went like this - 20 hour break-in period
During whole of run in period frequently check engine oil levels and top up as necessary as it is normal for oil consumption to be high during the run-in.
FIRST 10 HOURS
- Do not operate below 1500 RPM for extended periods of time
- Do not exceed 3/4 speed
- Do not operate at one speed consistently.
NEXT 10 HOURS
- Occasionally operate at full throttle for up to 5 mins at a time
- Avoid full throttle acceleration from idle speed
- Do not operate at full throttle until the engine reaches normal operating temperature
AFTER THE BREAK-IN PERIOD
- Change the engine oil and filter
It’s important to remember to get the engine serviced one year from
fitting or at 100 hours whichever comes first. I mucked up and thought it was one year from break-in and ended up nullifying the warranty - doh!!!
You’d think after 3 years I’d get fed up of looking at the engine - but no I can’t resist it
. My excuse is I just need to let any residual fumes out of the engine.