Re: New/Rebuilt 90hp Merc breakin.
I haven't heard of either. <br /><br />To tie up and run stationary is putting significant stress on the engine that wouldn't be there if the boat was moving.<br />--------------------------<br />First of all, a rich oil mixture is usually warranted.....25:1 which is a quart per 6 gallons.....so if your engine runs oil injection (50:1), add a pint of oil to 6 gallons when you fill up for the first 50 hrs to add to the 50:1 from the oil injector and you have the rich mix.<br /><br />All the new engines (and one rebuild) I have broken in have had a different strategy (so why should your rebuild be any different). <br /><br />They (the OEM) said for the first 50 hours don't load the engine, run at varying speeds and avoid WOT for the first few hours. <br /><br />Went something like this:<br /><br />(Boat needs to be lightly loaded)<br /><br />Idle around for a half hour or so while running the throttle up and down periodically, but don't get on plane.<br /><br />Then punch out and get on plane quickly and throttle back to just maintain plane (minimizing load on the engine yet getting the rpm's up).<br /><br />Run there for a couple of hours and during that time periodically goose it and return to the just on plane configuration.<br /><br />At the end if this exercising a couple of quick runups to WOT and back down are in order.<br /><br />Then for the next 48ish hours don't lug the engine, nor run at WOT for extended periods. <br /><br />The main thing you are trying to do is to polish off the rough spots on all these new parts without overheating the powerhead. Since you are going to be running metal on metal the engine will tend to overheat....that's why the recommendations to reduce the loading to reduct the opportunity to overheat.<br /><br />I've broken in probably half dozen new engines (one rebuild as I said) and never had any problems, and never idled them for extended periods when new.<br /><br />HTH and good luck.<br /><br />I still remember breaking in my boats for the first time and it was surely a memorable experience.<br /><br />Mark
