1999 Polaris SLH, SLTH, SLX, SLTX, PRO785 Factory Service Manual, Page 170Get this manual
ENGIN ElCOOLlNG DisassemblyInspectionPolaris Engines 15 Remove cylinder head cover and inspect sealing surfaceClean and inspect groove in cylinder for damage or debrisReplace both cover O-rings upon reassembly
16 Mark cylinder heads so they can be re-installed on their respective cylindersRemove cylinder heads and inspect sealing surfaceClean and inspect groove in cylinder for damage or debrisInspect surface of cylinder head