What’s the best way to flush the system to find and dislodge impeller remnants?
My Volvo Penta 5.0L GXiC-270R began overheating leading to a Thermostat and Impeller change. The Impeller was <2 years old with only ~25 hours but was chewed up. Drained and back-flushed through the flush-port (blue cap in the engine bay), ran the engine off hose-water, thermostat opened correctly ~150 degrees. Put the boat in the water, ran great, temps normal. Stopped for about 10 mins to do some boat cleanup, started—overtemp. Shutoff motor to allow it to cool down, restarted, normal temps back to my dock. I suspect pieces of impeller still floating around the cooling system causing intermittent blockage.
Raw water enters the boat through the seawater openings on the outdrive and passes through a Power Steering Cooler en route to the Raw Water pump. I see some people recommend disconnecting hoses connecting the Power Steering Cooler, but I don’t understand from the flow diagram how impeller blockage could occur here when water is exiting through the intake ports on the outdrive when I hook up my water hose to the flush port.
Suggestions?
Could partial blockage from impeller remnants at the Power Steering Cooler still allow enough water to exit while flushing, but not enough to allow adequate cooling at lower RPMs?
Or could the problem be intermittent blockage in the manifolds/risers? If so, what is the best way to flush debris out of them?
Note: I cleaned the thermostat housing pretty thoroughly when I changed the thermostat, but other than water, I didn't run anything through the hoses that attach to the housing.
My Volvo Penta 5.0L GXiC-270R began overheating leading to a Thermostat and Impeller change. The Impeller was <2 years old with only ~25 hours but was chewed up. Drained and back-flushed through the flush-port (blue cap in the engine bay), ran the engine off hose-water, thermostat opened correctly ~150 degrees. Put the boat in the water, ran great, temps normal. Stopped for about 10 mins to do some boat cleanup, started—overtemp. Shutoff motor to allow it to cool down, restarted, normal temps back to my dock. I suspect pieces of impeller still floating around the cooling system causing intermittent blockage.
Raw water enters the boat through the seawater openings on the outdrive and passes through a Power Steering Cooler en route to the Raw Water pump. I see some people recommend disconnecting hoses connecting the Power Steering Cooler, but I don’t understand from the flow diagram how impeller blockage could occur here when water is exiting through the intake ports on the outdrive when I hook up my water hose to the flush port.
Suggestions?
Could partial blockage from impeller remnants at the Power Steering Cooler still allow enough water to exit while flushing, but not enough to allow adequate cooling at lower RPMs?
Or could the problem be intermittent blockage in the manifolds/risers? If so, what is the best way to flush debris out of them?
Note: I cleaned the thermostat housing pretty thoroughly when I changed the thermostat, but other than water, I didn't run anything through the hoses that attach to the housing.
