Poll, Tell me yay or nay on this photo of piston scoring

[judah34]

1976 Johnson 70hp. Had trouble this year with it. Did a head gasket and had 123/125/121 top to bottom compression. Ran the boat all week last week and the shop I took it to was supposed to pressure test the lower unit and change the oil. That never happened and I had a lower unit failure. I had assumed I had a engine seizure so I tore the power head off. So If I can get the parts to fix the lower unit should I just slap this powerhead back together? ran great all week. But I found scoring on the bottom piston. Which I am kind of thinking was always there. Or do I throw in the towel parts it out and get something newer that may come with all new problems. Looking for guidance from others who have seen and ran with something looking like this. Thanks

 

[racerone]

I would first evaluate the lower unit repairs.-----I would not hesitate to take that power head off to replace that one piston.-----Newer used motors often come with surprises as well.

 

[judah34]

racerone...... would you just put a new piston in that bore? I have already spent so much time and money that I am almost all new parts with this project. I know with my dirtbikes we would just re ring or new piston on the same bore unless we saw piston skirt slap. I was thinking one new piston and rering the others . If I can square away the lower issues.

 

[racerone]

You would measure that bore and decide what to do.------Have you been throwing new parts at this motor only to discover internal engine issues, yes or no ?

 

[Faztbullet]

Nay...fix or replace with different mota

 

[judah34]

You would measure that bore and decide what to do.------Have you been throwing new parts at this motor only to discover internal engine issues, yes or no ?

Motor was apart for 10 years. put back together, new waterpump, powerpack, rebuilt carbs, tstat. Ran ok. Did new fuel lines, replace main Jets to make sure clear and did headgasket which brought my compression #'s up. Ran great for almost the whole week, Ran about 15 gallons of fuel through. Then the lower unit locked up. Which I thought was the powerhead until I stripped it down. Found a 79 evinrude lower unit local for $200 whih has good gears. So I can rebuild reseal lower unit and redo powerhead but will still be a 1976 which parts will become more scarce. Found a 2000 70hp With trim for $2200.00 so big decision I guess

 

[judah34]

For those on the edge of your seats waiting to hear if the Lower unit is fixable It is but........ too high a cost i think. See pics. Driveshaft trust bearing disintegrated. Causing enough play to spin the pinion inside teeth off.

I would be looking at trying to find a good driveshaft, pinion, Thrust washer and spacer and having to pay to have the driveshaft shimmed. Only to still have to deal with the powerhead. I think i am parting it out.

 

[Faztbullet]

Somebody been there before you as reassembled thrust bearing and shim incorrectly.

 

[racerone]

all good for parts.

 

[judah34]

New Motor
1979 Rude 75hp. 130 psi on all cylinders. Been sitting for 15 years in a basement. Less than 100hrs on the powerhead after rebuild. Was an elderly gentalmans Baja outboard. He got sick and it sat. $500.00!