1985-1995 Polaris ATV and Light Utility Hauler Service Manual, Page 272Get this manual
ENGINES 350Ll400L Water Pump 4Remove water pump impeller and check clearance measurementAcceptable clearance measured with dial caliper is between .020".040" (.05 -.1 cm)CAUTION: If the clearance is less than .020" (.05 cm) the impeller may grind against the caseIf the clearance is more than .040" (.1 cm) the water pump may cavitateThe photo at right illustrates checking clearance measurement with feeler gaugeThis method may also be used to check thickness by removing half of the putty from the impeller blade