Break In On 1992 Mariner 90 hp

[Sportsman558]

On my first 3.5 hours of break in I ran up to 5100 rpms, this is wot with the prop I have. Thruout this time I have kept varying engine speed. My question is am I screwed or should my engine be fine, and should I get a prop to bring me to 5500 now or wait till break in is done? I just replaced spark plugs, and was going to continue break in, but thought I should ask before I go any further. Also I'm running a 50:1 oil in the fuel tank with oil injection is this right? How long do I have to run this mixture for? I have been told 10 hrs for break in, but also 20 hrs. Any help is greatly appreciated.

 

[sschefer]

Re: Break In On 1992 Mariner 90 hp

On my first 3.5 hours of break in I ran up to 5100 rpms, this is wot with the prop I have. Thruout this time I have kept varying engine speed. My question is am I screwed or should my engine be fine, and should I get a prop to bring me to 5500 now or wait till break in is done? I just replaced spark plugs, and was going to continue break in, but thought I should ask before I go any further. Also I'm running a 50:1 oil in the fuel tank with oil injection is this right? How long do I have to run this mixture for? I have been told 10 hrs for break in, but also 20 hrs. Any help is greatly appreciated.

At 3.5 hours the engine has not broken in yet and compression is probably not up to par. As you get closer to the 10 hour mark, the compression should improve and along with that will be better RPM at WOT and easier starting.

There's normally no need to baby it after 10 hours unless your engine was built to performance specifications with super tight tolerances.

There will probably be 20 or 30 responses telling you how to break in your engine... If you get confused go get a copy of the owners manual and follow it. Everyone has their own way, Merc will tell you the right way.. Go to www.crowleymarine.com and use the parts catalog function to locate your engine. Select Misc from the diagrams list and you'll find the inexpensive owners manual for sale.

 

[Sportsman558]

Re: Break In On 1992 Mariner 90 hp

Do you think running it up to high rpms the first couple hours could have damaged the engine? I'm new to boats and rebuilds, your help is appreciated.