1973 85hp johnson o/b piston help

[damexican67]

Hey guys how are you all doing? A friend that I am helping out with his motor has discovered that the #3 cyl had only 5lbs of pressure.The #1 had 100-105lbs, the #2 had 110-115lbs, the #4 had 118-120lbs. As to why I removed the head to see if I could spot a problem and I noticed that the #3 piston was chipped and scored. Now my question is can I have some one walk me thru the steps for replacing the piston/arm. Or is it a bad idea for me to attempt this task?

 

[Joe Reeves]

Re: 1973 85hp johnson o/b piston help

Unless you have the proper service manual, and are quite mechanically inclined, I'd suggest that you back out of that job and keep a friend. It does become quite involved........ remove powerhead, tear it down completely, clean all components to seperate the good from the bad, have necessary machine work performed, and then comes the critical reassembly.

 

[rndn]

Re: 1973 85hp johnson o/b piston help

Totally agree with the above post. Unless you know what you're doing you can ruin the motor.

 

[tschamp20]

Re: 1973 85hp johnson o/b piston help

i did mine w/ no experiance and enjoyed it. drilled and tapped 25 or so bolts but hey.
get the manual for your motor.ebay will have it. the 115 and 135 hp manual will work as well.good luck its not that bad.