looking to get some help for my 59 sportwin 10hp

[Trooperx99]

i bought this motor 2 years ago and had it tuned, ran like a champion till last outing ,it started up as normal and i immediatly noticed a weird rattling noise, after adjusting the stator and tightening the recoil tried it again, still rattled, it was something internal, ripped it all apart and found scoring and scratches on the pistons and 2 stuck rings. the bearings and surfaces looked fine, now comes my problem. i cant for the life of me find a set of pistons that will fit. i find some of the same hp or a sportwin but a different year and different part #, could someone shed some light on this for me?

i went ahead and cleaned the rings out and now they move freely, and look nearly brand new. im wondering if that was the main cause to the rattle.

 

[F_R]

There is a bit of history about those pistons. They had a bad habit of beating the wrist pins loose. So, in 1961 they changed them to large roller bearings in the small end of the rods, and larger wrist pins. But all that resulted in the original parts becoming obsolete, and you have to change everything over to the newer style. That means rods, pistons, wrist pins, wrist pin bearings & circlips. But not the big end bearings. Look up an get the parts from a 1962 or 1963 parts book. They will fit the older motors but you must change everything as I listed. BTW, the new wrist pin bearings are the same ones used in 40hp and V-4 motors, so they are tough enough.

 

[Trooperx99]

ooh looks like i get to buy brand new now instead of used, awesome. im not going to have to bore it out or anything right? the cylinder walls have a nice mirror finish almost.

would the noise i was hearing be because of the pistons? or something else like the rings being stuck?

 

[farmboy75]

The cylinder walls should have a crosshatch pattern if it is mirror like it is worn out. Possible that just honing would work but likely you will need to bore and hone. You need an inside micrometer to measure for taper and out of round.

 

[Trooperx99]

i also noticed the crank case gasket appeared to be a liquid gasket of some sort, since i cant find a part# online for one can i use a liquid one again?

 

[F_R]

The correct stuff is Scotch 847, Evinrude part number 776964. Same stuff is used in the lower unit if you ever have to take that apart.

 

[Trooperx99]

awesome thank you, also i noticed someone removed the thermostat, or possibly they didnt come with one? its just an empty compartment.

also one last thing are all the piston rings the same size?

 

[F_R]

If it isn't in there, somebody figured they knew more than the engineers that built it and removed it. And yes, the rings are all the same, whichever piston style.

 

[HighTrim]

I would do the update that Frank described. It is well worth the time and effort. Go to aomci.org and post a wanted ad in the webvertize section. there are a few members there that sell the parts that you will need reasonably priced. Very often, the bores are fine. A light hone will be required with the new rings. You can slip your rings in your bore though, and measure the gap to see if they are still within spec.

 

[Trooperx99]

i just ordered everything frank suggested actually got everything for less than 200 bucks so thats well within my wallet being happy, what do you suggest to hone with, ive seen members say a scotch brite pad and some wd40.

 

[HighTrim]

yeah you can do what we call the 50 cent hone job, or get a hone. They are not expensive.

Check you tube videos to help with your first time. Ensure you follow all proper torque, especially on the rod caps.

 

[Trooperx99]

i read somewhere that the honing tools can get caught up on the exhaust ports, im not sure i want to risk that too much, also i found an old service sheet for my motor and it says 180-186 inch lbs of torque for the rod caps, does that sound right? thats only roughly 15ft lbs and for some reason i think thats a little light.

 

[F_R]

A straight-stones hone won't get hung up in the ports. Ball-stones, well there are many sizes of those.

180-186 inch pounds is correct. Notice that is only 1/2 foot pound leeway. An inch-pound torque wrench is a must.

 

[Trooperx99]

okay sounds great, ill have to pick up those tools sometime today or before the parts arrive, cant wait to get my favorite motor back up and running.

 

[pro-crastinator]

immediatly noticed a weird rattling noise

Is this what it sounds like?

 

[Trooperx99]

kinda sorta but less grindy and more knocky, hard to explain should have taken video before i ripped it apart.

 

[pro-crastinator]

Thanks anyway.
My 7.5 is gonna get tore into soon. - Sounds like the same route yours is going.
I only hope that my rods and pistons are as "obtainable" as yours were.

Heck, your 10hp sounds like it should last forever after you finish your efforts.

best o luck

 

[Trooperx99]

i plan to have it last forever haha, once i get the cash i may buy spare everything just incase, i love my little 10

 

[Trooperx99]

found another possible problem not sure if i put it together right the first time, the gearcase is leaking so i may just need a new seal.

 

[Trooperx99]

If it isn't in there, somebody figured they knew more than the engineers that built it and removed it. And yes, the rings are all the same, whichever piston style.

it appears ive hit a snag, the 4 original rings that i didnt break fit fine, but the new ones seem to be rougly 1/16th too long and wont fit down the cylinder

heres a pic of a dry fit http://i.imgur.com/bpfCHnJ.jpg

its the correct part # and everything