Yamaha 9.9's Running Hot
Posted: Sun Jun 28, 2009 1:06 pm
It seems like my stbd outboard is running hot. The exterior cowling is hot to the touch, but the "pee" water is cool (approx. 85 F). I pulled the thermostat and noticed that it is corroded. After letting it soak in vinegar for a while, I tested the thermostat and found that it opens at 150 degrees F. This seems very low. Does anyone know what the factory t-stats are rated to open at; 150F, 165F, 180F, etc?
I ran the engine without the t-stat, which produced the same results as my first/second sentence. My engines are from 2006 and are equipped with a fresh water flush out port. When flushing water seems to be flowing through all chambers, but I haven't verified it by pulling everything apart. If the t-stat temperature is correct at 150 F, then I may have a blockage in one of the lines, (where it is not noticable). I'd boil test the port t-stat, but they are both original & have about the same amount of corrosion, thus I can't trust the results.
Also could a t-stat rated for 180F fail over time and open at a lower temperature, say 150F?
Thanks,
Chris
I ran the engine without the t-stat, which produced the same results as my first/second sentence. My engines are from 2006 and are equipped with a fresh water flush out port. When flushing water seems to be flowing through all chambers, but I haven't verified it by pulling everything apart. If the t-stat temperature is correct at 150 F, then I may have a blockage in one of the lines, (where it is not noticable). I'd boil test the port t-stat, but they are both original & have about the same amount of corrosion, thus I can't trust the results.
Also could a t-stat rated for 180F fail over time and open at a lower temperature, say 150F?
Thanks,
Chris