Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 165Get this manual
Piston Ring Installation 1Install the oil ring components as shownAlign upper oil ri ng rail ends with locating pi nSpread rings just enough to slip over piston
Piston Installation
1Align piston ring end gaps as shown
a End Gap End Gap End Gap End Gap End Gap -
Top Compression Ring Second Compression Ring Upper Oil Ring Rail Lower Oil Ring Rail Oil Ring Spacer
aower Oil Ring Rail
- Lower Rail has Flat EndsUpper Oil Ring Rail Upper Rail has Notched EndsOil Ring Spacerlocating Pin (Align Upper Oil Ring Rail Ends with Pin)
NOTE: Cylinder bores must be clean before installing pistonsClean with light honing, as necessaryAfter honing, clean cylinder bores with water and detergentAfter cleaning, swab cylinder bores several times with engine oil and clean cloth, then wipe with clean dry cloth2Lu bricate pistons, rings, and cylinder waU with engine oil3Install each piston in its respective cylinderInstall th second and top compression rings (''T'' side up)Spread rings just enough to sli over piston