Partingbout 1999 6hp Yamaha long shaft

Clint r

Well-Known Member
Well, put in a new impeller and still not pumping water. I believe it’s a head gasket so going to part it out. It’s a 2 stroke that uses gas/oil mixed at 100/1 so almost as little smoke as a four stroke. Motor runs great and starts first pull. Has a prop guard and charging system. Charging system may fit 8hp models? Taking offers on parts. I can send pics to anybody interested and I live in the Okanagan but will ship anywhere.
 
Well, put in a new impeller and still not pumping water. I believe it’s a head gasket so going to part it out. It’s a 2 stroke that uses gas/oil mixed at 100/1 so almost as little smoke as a four stroke. Motor runs great and starts first pull. Has a prop guard and charging system. Charging system may fit 8hp models? Taking offers on parts. I can send pics to anybody interested and I live in the Okanagan but will ship anywhere.
You sure the tell tale is not blocked.
 
Yep . I’m almost 100% positive. I can feel air/steam out of p hole when it’s running, and with leg off and compressed air blowing into pick up tube I can hear it escaping at the engine block somewhere. And absolutely no back pressure while I’m doing it. I also attached a small hose to the p hole stub and can blow air backwards through it with little or no resistance.
 
Yep . I’m almost 100% positive. I can feel air/steam out of p hole when it’s running, and with leg off and compressed air blowing into pick up tube I can hear it escaping at the engine block somewhere. And absolutely no back pressure while I’m doing it. I also attached a small hose to the p hole stub and can blow air backwards through it with little or no resistance.
Not sure ,but if you do a compression check will that not show a blown head gasket. A gasket set can not be that expensive. Sounds like a good engine with the charging unit. Good luck.
 
Hmmm, good idea. And my brother in law is coming out with his work truck and has a tester so I better look into that.
 
You could try to test for a blockage by taking out the thermostat and then see if you can squirt the garden hose through the thermostat housing and out the tell-tale. Shield any wires and connections from the water with whatever works.
 
You could try to test for a blockage by taking out the thermostat and then see if you can squirt the garden hose through the thermostat housing and out the tell-tale. Shield any wires and connections from the water with whatever works.
You can get help on this forum. Don,t give up on the motor yet.
 
So compressions pretty good on both cylinders. I don’t know how accurate my brother in laws compression tester is but top cylinder reads 146 psi and bottom cylinder 148 psi. I’m going To do a little research and see if there is a thermostat stuck somewhere, although I don’t see any obvious signs of one on this particular motor.

While we’re on the subject of motors, a friend of mine has a 10 year old 8 hp Honda he’ll let me have for $500.
Four stroke tiller motor. His uncle owned it and he inherited it as part of the estate. He says less than 400 hrs on it. Anyone have experience with these motors?
 
Sorry, unfortunately not. I’m up here in the Okanagan. Thanks a lot for the offer though.
 
I've just been reading over what you've done with this motor - I had a similar problem with a 25 HP Yamaha. With the leg off, if you jury-rig a garden hose to the water tube going up to the power head and run water through that, if you then get water out the p-tube, then you have a water pump problem...in my case, some mud-dauber wasps had made a very nice home in the water pickup area underneath the impeller and that chrome wear plate - NO water was getting into the water pump. Pull off the water pump housing, lift out the impeller, and that chrome steel wear plate underneath, too - and check to see that there are no blockages between the water intakes on the gear-case and the bottom of the water pump.
 
Buy that Honda for $500 because its a good deal. But still, fix your Yami and sell it or the Honda. It's not too often that people make money on outboards. You could get $900 for the Honda.
 
so all the research I’ve done kept coming back to a couple YouTube vids of an 8 horse Yamaha with a stuck thermostat. While not the exact motor as mine, it’s close enough that I took a shot and pulled the cover off and sure enough, thermostat corroded and not opening. Put it back together minus the offending part and it pumps water like a champ. I’ll order a new one tomorrow and put it in then she’ll be good as new.
 
so all the research I’ve done kept coming back to a couple YouTube vids of an 8 horse Yamaha with a stuck thermostat. While not the exact motor as mine, it’s close enough that I took a shot and pulled the cover off and sure enough, thermostat corroded and not opening. Put it back together minus the offending part and it pumps water like a champ. I’ll order a new one tomorrow and put it in then she’ll be good as new.
Good for you. I knew it could be fixed. Run for another 10 years.
 
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