Removing saltwater seized piston on Mariner 5hp

E

eddie the boat guy

Cadet
Joined
Oct 29, 2024
Messages
9
Is there any way to remove a very seized piston by sacrificing the piston to save the cylinder, I have tried penetrating oil,brake fluid heat and the piston won't move a bit
 
R

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,411
If motor was submerged and then left sitting , then crank and bearings will be scrap.----Worth is scrap / parts value.
 
C

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,073
Stick a brass drift thru the spark plug hole and give it a rap with a 4 pound hammer.
 
R

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,411
Putting it in a freezer might shrink the piston a bit to help remove it.----But the cylinder will be corroded.----Perhaps distorted as well.-----It may run after all the work.----I think there are better projects available !
 
Scott Danforth

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,226
heat the cylinder, then use a can of freeze-it on the piston.

another idea, use a hole-saw that is the diameter of the inside ring grooves. you have to be dead-centered on the piston. you saw thru the piston, and the piston comes out in bits, then you can peal the rusted rings from the bores.
 
flyingscott

flyingscott

Fleet Admiral
Joined
Apr 8, 2014
Messages
8,151
If the head comes off of that motor you can try this. Mix ATF and acetone together in a 50/50 mix and fill the cylinder. Let it sit a week pull the head off and find a Hydraulic press and take your chances.
 
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