Mercruiser 165 straight 6 Overheating Issues

[rsmith.5682]

Recently purchased a 1978 Searay with with straight 6, 165 Mercruiser inboard outboard on it. Having issues with it overheating while at idle and at higher rpm (over 2000). Runs fine between 1000-2000. Had the Marina replace the impeller, water pump, and thermostat. Still having issues. Pulled out of water as Marina wanted more $$ to fix the problem they said they all ready did. Did some trouble shooting out of the water with ear muffs and garden hose. Still running hot when running just off of the ear muffs. When we removed the water inline on top of motor and put garden hose directly to motor we had no overheating issues. Pumped water from outboard into back of boat and seemed to be getting water flow just not sure if enough. Any ideas on what could be causing the issue?

 

[Scott Danforth]

back flush the hose. most likely the power steering cooler is full of pieces of the old impeller along with other things.

 

[kenny nunez]

Also, another thing to check, with the engine running on a flush out and the hose from the drive pump removed try to see if you can put your thumb over the end of the hose to stop the water flow. If you can then either the plastic water pocket cover is melted or you are losing the flow somewhere else. The only other place to look is the hose from the bell housing to the gimbal housing.

 

[rsmith.5682]

Tried back flushing hoses, no power steering cooler. Hose from engine runs right to back of boat. Have water flow but it seems to sputter, Think we are going to have to take off back end and search thru there