2hp knock

[mike n]

hello, i have a 1985 2hp evinrude that knocks/rattles. tried a piston but didnt make a difference. i believe this was a 100:1 motor. the connecting rod to crankshaft bearing looks possibly worn but hard to tell.is there a common thing that goes wrong with them? thanks

mn

[johng]

100: 1 was the Death of that Motor. Also if the Impeller failed that could have been a problem with overheating the Internals. Try and locate a used Powerhead your best Plan. Motor had no Needle Bearings on the Rod and Crank. Run at least 50: 1

[Mumbles]

Actually, these motors do have needle bearings on both ends of the rod along with needle bearings on the cranks mains. Still needs 50:1 mix or heavier.

[mike n]

It has needle bearings.do they go bad ? Does the crank wear out. Should I get new bearings?

mn

[Mumbles]

The rods needles and liners can wear down. I believe they are the same as ones used in the six horse motors and are getting harder to find new. OMC says the lower crank bearing has to be replaced along with its housing but that isn’t true. I’ve pressed them out to change the seal and replaced them with off the shelf bearings. You replaced the piston? Was it used or a new one? A used one could be worn causing piston slap which can be confused with a knock. If the motors was run on 100:1 for a long time, everything inside could be worn out.

[mike n]

It was a new piston.just thought I’d give it a try. That was when I got the motor. It came with a canoe. About 18 years ago. After that, I threw it in the shed. Figured I’d give it another try. Don’t mind spending a little money because it’s in decent shape but don’t want to go too crazy

mn

[fleetwin]

Are you sure it is the powerhead?? Sometimes those rewind pulleys get sloppy and bang/rattle around… You had the powerhead apart and put a new piston in it…Did you bore it oversize, or just hone it? Is it possible that you honed too much, actually boring the cylinder oversize a bit? Did you have the crank out? If so, did the lower needle bearing look OK? These get rusted pretty easily, and usually fall apart when removed from the crankshaft. What does the noise sound like to you? Just it sound like rusty/worn bearings, or does it sound like piston slop? I suppose it is possible that the gearcase is torn up making the noise you are hearing as well…Was the gear lube OK when you changed it?
Back to my original thought. Try removing the recoil and wrapping a rope around the flywheel to start it, see if the noise goes away…
Any chance you could post a video of the engine running?

[mike n]

it sounds like it is high up,rattle/knocking.not near the gearcase. the geacase oil looked good.when i replaced the piston, i gave it a very quick hone to deglaze the cylinder.doesnt sound like rusty bearings,maybe worn?the bottom crank bearing looks ok.definitely not rusty. its apart right now so cant post a video anytime soon.the only thing that looks visibly worn is the connecting rod bearing sleeve.its very shiny towards center. i would like to try one buts its pricey and i dont know for sure. i didnt run it with the recoil off but everything on it seems tight.

mn

[Mumbles]

Worn splines on the driveshaft and in the bottom of the crankshaft can make noise to every time the motor fires.

[billw]

Maybe a stupid question, but but I don’t see it mentioned here, yet: Is the coil hitting the flywheel? Is the mag plate friction screw installed and snug?

Also, like Don said, don’t discount the lower unit. I have known a couple of pretty good mechanics over the years that thought a power head had a knock, only to find a bad tooth on a lower unit pinion gear. Sound transmission can be funny. (And no, it wasn’t me, luckily.)

Long live American manufacturing!

[Author]

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