" Water tube" overheating?

Hello all, I have a 89 150 that alarms at warm up mid speed and hi speed. Changed thermostats, impeller, checked the PRV, sensors, tach, gone through wires and am about to sell cause I am agrivated to death. Just read here that one of you in canada had a similar problem. You found it to be the water tube? Can the water tube be changed without powerhead removal? Please help or I have a nice 1989 Wahoo with a clean 1989 150. Thanks Bruce

You will have to ask around but there is a very good bilge cleaner that is used in the cooling system that works well for cleaning out the system.

Use salt - X if you run it in salt water

Have you checked the water pick up screens on the foot????? Remove them and clean them and also inspect behind them and flush motor using the flushing hose on the outboard with the screens off.

[kingfish]

brucelee -

The symptomology for our split water supply tube was low speed overheating. Eventually the split apparently widened and we had some occasional overheating at higher RPMs and the low speed overheating needed to be overcome by running up around 1500 RPM rather than 1000 RPM. The split caused a loss of water pressure - that was diagnostic after all the other parts were replaced. The water jacket would not fill up at low RPMs so the top cylinder(s) would not get cooling and would overheat. Put your motor on earmuffs, pull a thermostat or thermostat exit line, start the motor, and see if water comes streaming out up there or not. If it doesn't, you may have a problem under the powerhead like the water tube or a gasket.

If your overheating is across all RPM ranges, I'd suspect a blockage somewhere.