Compression on 1997 Johnson Oceanrunner 150

[planetsix]

I bought this motor on a boat a few years ago. This is my first Johnson and I have no idea what it's life expectancy should be, nor do I know what kind of life it lived before I got my hands on it. I would like to do a comp test on it, but haven't a clue what values I should be looking for. Any numbers, or info on inherent dangers associated with owning a 7 year old Johnson, would be greatly appreciated.

 

[Solittle]

Re: Compression on 1997 Johnson Oceanrunner 150

Welcome Mr. Planet!! The age of the motor means little. There are lots of folks here who run 20 year old plus motors hard year after year. Care and regular maintenance are what counts. Plan on buying the OMC service and parts manual for your motor. You can find them here:<br /><br /> http://www.theoutboardwizard.bizhosting.com/parts_service_and_owners_manuals.html <br /><br />On compression - It is more important that the readings be relatively even accross the cylinders say within 10-15% of each other. Probably should get readings of 100 psi or more.<br /><br />I would hope that you have been giving your motor regular service in the years you have had it. Change plugs and gear oil at least once per yr. - water pump every 2-3 yrs - stabilizer in the fuel if you have to leave it sit for a couple of months - fresh water flush every trip if run in salt water - grease as needed And don't forget the trailer.

 

[planetsix]

Re: Compression on 1997 Johnson Oceanrunner 150

SoLittle --<br /><br />You brought up another good point that I've wondered about: flushing the system. I leave the boat in salt water and have fresh water down at the dock, but only flush it about once a month. I run the boat a-plenty, last year totaled more than 1500 NM (I'm guessing over 200 hours). I've heard mixed reviews about flushing every time I get back to port. What's your opinion.<br /><br />Other than that, I take pretty good care of thepowerplant -- I just am worried about it's past coming up to bite me (if it wasn't taken care of.)<br /><br />Thanks for the link, that's awesome. The water pump is on my agenda for this winter.

 

[Solittle]

Re: Compression on 1997 Johnson Oceanrunner 150

Well Mr. P here are my thoughts - First I am not a professional wrench but I have run outboards of varoius sizes in salt water for over 30 years. My take on it is that it dosen't cost a dime to flush. If (here is the debate) it reduces the buildup of crud in the water passages then it is time well spent. I have pulled the heads on a few and you wonder how the motor had any water circulating at all with the crud. I am not a fanatic about flushing but will do it 9 times out of 10.