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No exhaust through prop hub

Posted: Sun Apr 30, 2017 1:57 am
by catalacmarc
Just bought and installed two clean used model 6G8 Yamaha 9.9s. Both started right up but the first one only ran a few minutes the next time and wouldn't start there after. That is not the wierd thing. What is wierd is that there is no exhaust through the prop hub? Water was also not going into the leg, just going out the normally unused second water outlet on the motor base. A real rip off, gravel in the fuel pump, carberator assembled wrong and a leaky cracked gearbox. Good news and the reason I haven't tooed it back on the guy's lawn is that the leg looks mint and compression is 140+ in each cylinder. Next stretch of good weather, I'll pull the motor and see what is going on with the exhaust manifold. Any thought?

Re: No exhaust through prop hub

Posted: Tue May 02, 2017 10:39 pm
by amytom
Pull and check the plates on the side that make up the exhaust/water mixer. I'm sure there's a technical term for it but I don't remember.
With the other issues maybe they didn't put the plates together right or missing gaskets?

Re: No exhaust through prop hub

Posted: Wed May 03, 2017 7:04 pm
by catalacmarc
Not sure what part you are talking about? As far as I can tell, the exhaust comes out of the manifold and mixes with the water that is injected into the leg, pushing it out of the leg. I have one of my coroded motors torn apart, I'll look at that. There is the "exhaust guide" that is used as both the top of the leg and top of the oil pan and the base of the crankcase. Maybe the crankcase bottom gasket is blown and exhaust is somewhere it shouldn't? It is a simple system, should be able to go haywire 6 ways and exhaust still out to go to the prop. Marc