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Early 80's 9.8 overheating

S

stevenT

New member
Hello, I have a mercury 9.8 that I have been trying to get to stop overheating for a month now. Replaced water pump assembly twice, new water tube seals and grommet, new exhaust baffle plate and gaskets, powerhead and base gaskets. After all that finally tore motor down and found water had been getting into crankcase so I replaced lower bearing and piston rings and all seals as well as new reeds. Motor starts up and runs, but will take a little while to get water into the thermostat housing. Shortly after startup steam or smoke begins shooting from the tell tale or thermostat housing if I have cover off and the exhaust plate gets hot quick. I have hooked a hose directly to the water tube and it will run great and stay completely cool. If I put the lower unit in a bucket and spin the drive shaft with a drill I get water shooting from the water tube. Out of ideas, any help is appreciated.
 
When running in a bucket of water is the water line WAY above
The pump? Try that and see if that helps.
Has it been ran in salt water?
 
..."little while to get water into the thermostat housing."

What thermostat housing? What year is this?

Jeff
 
Have it in a 55 gallon drum and the water level is around 10 inches above the cav plate, only ran in fresh water all water passages were very clean. As for the year the best we could find was most likely 1981.
 
I took the exhaust cover off and found that after replacing all the crankshaft seals and every gasket on this thing I have water in the bottom cylinder again, and milkshake type fluid coming from the carb throat and inside the driveshaft housing walls.
 
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