Mercury 35/40HP 2 Cylinder Outboards Service Manual PN 90-42794--1, Page 270Get this manual
Reservoir Assembly Removal ACAUTION
DO NOT ADJUST OR REMOVE REVERSE THRUST VALVETHIS VALVE IS PRESET AT FACTORY FOR PRECISE REVERSE THRUST PRESSURE AND DOES NOT REQUIRE ADJUSTMENT
3Remove four screws securing reservoir to manifold
1Remove manual release valve from manifold DO NOT remove or adjust reverse thrust valve