85 15 hp rebuild

[SCduckhunter]

Im back....so after much grief ..with the help here I found my issue http://forums.iboats.com/johnson-evinrude-outboards/85-15-hp-issues-627251.html .....after some discussion with my wife and much thought.. I decided to pull the trigger and do a full powerhead rebuild..I found the no2 piston ring groove with a large burr in it upon tear down not allowing the ring to fully and easily float...I took the block to the machine shop at 11:30 this past Thursday morning..I left instructions to hone cylinders or bore it if he felt that was the best route to go..he called me yesterday morning at 10:15 to tell me my block was ready for pickup!!! 25$ to hone and he said aside from one small spot it was 98% he felt confident that the spot would give me no trouble at all...I ordered new pistons new bearings an entire powerhead gasket kit and will be ready to put it back together when the parts all arrive...I'd like to know if anybody has any tips or heads up on the rebuild..things to double check or pay extra attention to...I took tons of pictures during tear down and have the manual..also I'd like to hear any advice on the break in period... I know to run much richer oil. Is 25:1 too rich.. I have 2 new set of plugs one set I'm willing to foul running it very oil rich...for 4$ I'll eat the cost....thanks in advance

 

[Will Bark]

Re: 85 15 hp rebuild

Go to Leeroy's Ramblings and you should find a lot of info that will be useful. Good luck

 

[SCduckhunter]

Re: 85 15 hp rebuild

Already have it bookmarked and ready to go on my phone I love that site he's so helpful..he comes on here too from time to time as well

 

[raczekp1]

Re: 85 15 hp rebuild

flatten the head surfase also,
in machine shop did they check if block surface is flat? when i rebuilt block they found some depression in the midle of block surface

 

[SCduckhunter]

Re: 85 15 hp rebuild

I took the head in as well.. The entire block was acid bathed and all gasket surfaces were cleaned by them..they did all of it..my father in law knows them so they hooked me up with top notch service...the entire block and crank and connecting rods were given a professional clean bill of health......really just looking for a bit more detailed break in info such as rpm lengths and limits...and any advise on things to pay extra attention to when replacing pistons and putting block back together...I've never gone this deep into a 2 stroke motor..a 4 bolt main 454 and that I know..this not so much...thanks

 

[raczekp1]

Re: 85 15 hp rebuild

pay attention when installing upper and middle bearing.
run 10 hours in mix 1:25, reach only 50% max rpm ad the and of break in hours reach 70%

 

[raczekp1]

Re: 85 15 hp rebuild

pay attention when installing upper and middle bearing.
run 10 hours in mix 1:25, reach only 50% max rpm ad the and of break in hours reach 70%

 

[SCduckhunter]

Re: 85 15 hp rebuild

Im giessing that i need to make sure pins in crank.and bearings are seated properly...how much RTVshould i use when mating the crank.case covers? I saw leeroysramblings where he reccommends rtv ing the seam...

 

[AlTn]

Re: 85 15 hp rebuild

you really should get the OMC Factory Workshop Manual for this job as it'll have all the torque and clearance figures and it will take the guess work out of putting it back together correctly. Check out the youtube video titled , not exact but should get you close, Small Girl Rebuilds Small Outboard Motor.

I think you are referring to Loctite 518 or Gel Seal for the crankcase halves seam. You'll need gasket sealing compound < Johnson/Evinrude Gasket Sealing Compound from the dealer is cheap , sorta messy and defintiely sticky.>

Just read completely through the procedures for the rebuild first and take notes, ie. the orientation of the oil holes in the rod, getting the rod seams perfectly aligned, etc.

I recently rebuilt a 1971 18 hp. for the first time and it's a process that required a lot of concentration and a quiet environment for me.Keeping those needle bearings in place while setting the crank is not for the impatient.

You shouldn't have any real problems, just keep the frustration in check and take your time.

 

[SCduckhunter]

Re: 85 15 hp rebuild

I have a SELOC manual for the motor ill look into getting a factory one...thanks for the advise I'll defiantly keep it in mind.. How long after the 10hr break in period did you wait until you used the engine normally,.. Duck season starts in 2.5 weeks I'll have most or all the 10 hrs done by then

 

[raczekp1]

Re: 85 15 hp rebuild

hm do you hunt and run motor at WOT?i think runing motor in slow speed and do the sidesing is nice

 

[SCduckhunter]

Re: 85 15 hp rebuild

I hunt 5-6 days a week...its a 15-25 minute run to some of my spots at wot... Then a good bit of idling then the return wot run...I'm figuring I can get 5-7 hours of quality break in time with the motor in the barrel and then I'll put it back on the boat and do some early morning scouting in basically slow forward or forward idle no wot..I'm hoping to beable to use it normally by early December it'll have approx 25-30 hrs on it by then..my motors average 300 hrs a year...I use em alot I'm on the river in one of two boats 5-6 days a week...

 

[AlTn]

Re: 85 15 hp rebuild

1978 9.9/15 hp. Factory Manual...First Houro not operate engine at continuous full power for the first hour of operation.After 15 minutes of slow to half throttle operation,we recommend a short burst of full throttle operation every 5 to 10 minutes..Run at full throttle for about 90 seconds, then return to half or less throttle. Second hour: Bring boat to plane attitude and reduce power to three quarter throttle ( approximate ) while maintaining planing attitude. At intervals during the second hour,apply full power for periods of one to two minutes, returning throttle to original setting - three-quarter throttle for cooling period. Avoid continuous full throttle operation for extended periods during the next three hours. Note: the manual recommends 50:1 mix during break-in. Check telltale water flow frequently during break in.