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O.K. here's my story. Been trying to figure out an overheat alarm problem for several months now and thought I had it fixed, but it came back. Have done all the steps as suggested on this site and by the book, pulled both t-stats and checked good, both temp. sensors check good, replaced H2O pump. Found and repaired a bad ground in boat wiring harness as well as a shorted battery. All ran fine until last weekend when alarm went off again with RPM reduction. Checked all of the above once more with addition of PRV. found that water was coming from two back ports at high idle. About 900 RPM on the problem motor, but not on the other motor. Removed PRV, which appears good, no damage or visible cause for sticking, so I "shimmed" it with a couple of hose washers to increase tension on the spring and ran it. Now I get no alarm, but also even at cruising speed, 4000 RPM, see very little water coming from relief ports. Ordered parts to replace PRV, spring, gasket and grommet. Does anyone think this could be the problem or possibly something worse? Any helpful advice appreciated.