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Question:

mercury outboard water pump?

mercury 9.8hp.installed a new water pump impeller and still no water circulating through engine. no blockage anywhere. now what??? i`m stumped at this point.

Answer:

I have seen this many times on 9.87.5Merc'sThere is a plastic o-ring under the power head and it is probablly melted closed.There is a way to fix it without removing the powerhead.Remove the lower unit and pull out the water pickup tube.Then use a piece of brake line 5/16th sharpen on a 45 degree angle and push up the opening for the water pickup to open the passage.This will fix your water problem.
I have seen this many times on 9.87.5Merc'sThere is a plastic o-ring under the power head and it is probablly melted closed.There is a way to fix it without removing the powerhead.Remove the lower unit and pull out the water pickup tube.Then use a piece of brake line 5/16th sharpen on a 45 degree angle and push up the opening for the water pickup to open the passage.This will fix your water problem.
This engine has a hose that discharges a small stream of water when running. But most of the water is discharged through the center of the prop. It's not uncommon for this hose to plug from small bits of sand and mud. a small wire can unplug it. If the thermostat is stuck this might cause what your describing, but it's rare. Is it possible that the little round drive pin that goes between the impeller and the drive-shaft, broke or came out during assembly? Or the guide tube in the lower leg (intermediate housing) is not in place of blocked. Sometimes the sleeve that seals this gets crumpled under during installation and can block the flow. My recommendation is to disassemble and check each step until you've found the problem, or satisfied your self that everything is right.

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