I have replaced 10 blade water pump and new 130 degree thermostat and grommet. It pumped fine in the water drum and at the dock. When she got up to WOT the pump stopped pumping and my overheat light and alarm went off. I quickly shut her down and got towed back to the dock. Getting her home i took off the lower unit and the impeller was in good shape. I put it all back together and ran her in the water drum and she spit water just fine. Went out on the lake and at the dock i checked the discharge of water. Pumping just fine. Got her out and at almost at WOT and my overheat light and alarm went off again. Shut her down and thank god the wind was in my favor and drifted back to the dock. After blowing all water outlets and lines with compressed air there were NO BLOCKAGES. I pulled the cylinders head off and found #2 compression ring on the head gasket SPLIT and hanging down into the water jacket. I figured the compression going into the water jacket probably was causing erratic pumping at idle and slow speeds, and not pumping at WOT issues . I replaced the head gasket and ran her in the water barrel and I had NO WATER PUMPING AT ALL. The head gasket solved a lot of other issues that it had. Runs smooth as glass, starts right up and acting like a new motor. However this water cooling issue is driving me crazy. I took off the lower gear case off again today and again everything was fine again. When I install the lower end the tube from the pump to the power-head is attached and tight. I always place the grommet on the bottom of the tube just barely attached. Installing the lower end so i can see the grommet going down into the pump housing, so I know the pick up tube is attached correctly. I started the motor with the thermostat hose off the housing and no water running through the power-head. Please help!!!!
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