Just purchased a used sailboat with the Yamaha T9.9... 4 Stroke. Motor starts fine...spits a little water then nothing. Seems to be dry; then starts gurgling and finally spitting a steady stream; then stops spitting again...Cyclic.. I rebuilt the water pump. New impeller, etc.... Everything is in solid. Still the same sympton... I can disconnect hoses from the power head and get no flow to the pee-hole...Any ideas/suggestions would be appreciated... Owner said the motor was very low hours.... Looks like new...
Solved the problem today.... Removed the Exhaust cover and inner exhaust plate. Found several orifices clogged with caked salt and some corrosion. Removed the cylinder head and found the same problem throughout the cooling water path.... Used hot water and a dental pick to remove most of the buildup. Two of the tubes that run adjacent to the spark plugs were so caked that I had to "drill" out the salt...Started with small bits and worked my way up until I got clear passage (checked by blowing through the tube with a rubber hose). Reinstalled everything and tried the flushing attachment. The motor spews water now!I had rebuilt the water pump and checked the thermostat. The local Yamaha dealer told me to hang the engine up and trade for a "New" motor because after 10 years this engine had to be shot... Major corrosion and salt build-up. He offered me $600 for a trade-in. Had nothing to lose so took the plunge at disassembly and repair. I learned a BUNCH and will probably add the tear-down to a periodic maintenance cycle so I don't have to deal with the problem again. I will continue to flush the motor after each use...I love it when a plan comes together!
1995 Yamaha T9.9 Electric start Water Circ
Linear Mode
