98 Johnson Oceanrunner-150 (carbureted)

[MikeMoonpie]

Hello, and thanks.<br /> Seems my fuel tank got dirty, and some trash made it to carbs. An "unreliable marine shop" cleaned them, and it ran for a mile until I noticed a loss of power and shut it dowm. They did not plug the oil injection system back to the wiring harness behind the air cleaner, so it cooked #6 piston, and reduced compression on the rest to 80-90psi. I have torn the engine down, and the rest of the cylinder walls look good. Should I bore it all, and replace all pistons? I promise to disconnect this ioil injection system when done. 50 to 1 mixing is not rocket science. Thanks.

 

[Spidybot]

Re: 98 Johnson Oceanrunner-150 (carbureted)

Depending on how it looks, it would be the obvious way to treat all cyls the same way: Rebore and new pistons etc.<br /><br />You want all cylinders to work equal after the rebuild so redoing only some of them isn't the way to go.<br /><br />BTW: Is the workshop aware of the problem? If so, they should pay (at least some of) your costs.

 

[MikeMoonpie]

Re: 98 Johnson Oceanrunner-150 (carbureted)

Yes, they know I had trouble immediately after their grubby little hands touched it. They claim that it is merely a coincidence, and that the oil injection pump failed. I know that I could pursue this through legal channels, but feel certain that it would not prove cost effective. I was relaxing on vacation on Anna Maria Island, had no tools, and the two twelve year olds with me were eager to fish. I sense they viewed me as ripe for the picking. Can't think of a nice thing to say about Mikes Marine in Bradenton....

 

[MikeMoonpie]

Re: 98 Johnson Oceanrunner-150 (carbureted)

By the way, the crank and bearings look great! It never did rattle, knock, or lock up. The engine was new when I got it, and does not have lots of hours on it. Do you think these components will be OK? Any other advise will be greatly appreciated.

 

[MikeMoonpie]

Re: 98 Johnson Oceanrunner-150 (carbureted)

...and, would polishing some of the surfaces in the carburetors improve air flow to the point where it improves performance, and is worth the effort?<br /><br />....anything else I should, or could do while it is disassembled, to improve it?<br /><br />Thank you so much.....

 

[seahorse5]

Re: 98 Johnson Oceanrunner-150 (carbureted)

Mike,<br /><br />Unfortunately, it was not the "VRO" or the harness unplugged that ruined #6 cylinder. The "VRO" mixes the fuel and oil in the pump BEFORE it goes to the carbs, so it is impossible to ruin one cylinder. Can you imagine what your motor would look like inside if you ran it without oil? You even mentioned that the crank and bearings look good, they wouldn't if there was a lack of oil. The Feb 2000 issue of Trailer Boats magazine has the complete story on how the VRO works and why it gets blamed for engine failures when it's not at fualt. Not plugging in the harness does not affect the VRO operation, it is only the wiring for the alarm system.<br /><br />The trash in your carbs probably restricted the #6 main jet, causing the motor to run lean and detonate, ruining that piston. I'm not saying your "mechanics" were not up to snuff, but the damage was probably already started before they cleaned your carbs.

 

[Spidybot]

Re: 98 Johnson Oceanrunner-150 (carbureted)

Have to agree with seahorse. Lack of lube won't affect only certain parts.<br /><br />However, I'd still pick the way forward as 'better replace all that looks even the slightest worn' because taking it apart once more to replace the last little item would be too foolish.<br /><br />Unless your experienced with polishing (+balancing +calibrating) carbs and intake channels, I'd say 'Don't'. Rather a standard setup that runs as meant to (even regarding stability etc.), than a homemade improvement.<br /><br />Ofcourse you can rebuild it using performance parts, but then you're beyond the point of thinking about what parts to keep. Performance motors have to be in the best of conditions in all respects and you'd have to get the full kit to make it work.

 

[MikeMoonpie]

Re: 98 Johnson Oceanrunner-150 (carbureted)

Dear Seahorse, and UU...Thanks.<br /> I appreciate your responses, experiences, and input. I have done some light "polishing" in Ford cylinder heads to improve air flow. You guys know these 2 cycle engines more than me, but I do know that all "tweaking" to engines usually has a negative effect on longevity. They may run faster, but at the cost of shorter engine life, and dependability.<br /> Going to bore all 6, and replace all pistons. I was curious as to why just one cylinder, number 6, cooked. It makes sense that one lean carb would do it. As to removing the oil injection system, I still intend to do so. There is always this worry that it could stop, and alarm not sound. One less thing to be concerned about....