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Ok, this one is for lower unit experts at boats.net or any one else who has seen this. Over the weekend I did my first water pump replacement routine as advised by most mechanics I talked to.
I really did it out of couriosity more than anything else, because my water pump on my 2000 C115 has been doing fine with a strong side discharge (even at idle) and no overheat problems.
So I dropped the lower unit to see what kind of condition the (7) bolts were in and also the splines on the drive shaft. All were ok - a little bit of corrosion on the stainless bolts, but not bad, and the drive shaft splines had grease on them from the factory.
Now what I did find, or should say, did not find was the rubber seal as shown on page 6-1 of my Yamaha shop manual that looks like it is supposed to seal the bottom of the exhaust muffler to the top to the exhaust discharge in lower unit. Man, I looked everywhere. I see a place where a seal should go,but there's not one there.
I have been running this C115 hard for four years now in salt water, and taking good care of it. I am bothered that my (very expensive) shop manual shows a seal that is not in my motor - one that I bought brand new.
There is no sign of exhaust gas leak external of the motor around the junction of the lower unit and upper case. There is however, a little exhaust gas leak evident into the chamber where the water pump resides, for I found black sooty deposits on the side of the water pump housing next to the exhaust chamber.
My question is, does there need to be a rubber seal there as shown in the shop manual? Did Yamaha just arbitrarily or mistakenly not put one in there?
Any comments would be appreciated.
Ken K
Beaumont, TX
I really did it out of couriosity more than anything else, because my water pump on my 2000 C115 has been doing fine with a strong side discharge (even at idle) and no overheat problems.
So I dropped the lower unit to see what kind of condition the (7) bolts were in and also the splines on the drive shaft. All were ok - a little bit of corrosion on the stainless bolts, but not bad, and the drive shaft splines had grease on them from the factory.
Now what I did find, or should say, did not find was the rubber seal as shown on page 6-1 of my Yamaha shop manual that looks like it is supposed to seal the bottom of the exhaust muffler to the top to the exhaust discharge in lower unit. Man, I looked everywhere. I see a place where a seal should go,but there's not one there.
I have been running this C115 hard for four years now in salt water, and taking good care of it. I am bothered that my (very expensive) shop manual shows a seal that is not in my motor - one that I bought brand new.
There is no sign of exhaust gas leak external of the motor around the junction of the lower unit and upper case. There is however, a little exhaust gas leak evident into the chamber where the water pump resides, for I found black sooty deposits on the side of the water pump housing next to the exhaust chamber.
My question is, does there need to be a rubber seal there as shown in the shop manual? Did Yamaha just arbitrarily or mistakenly not put one in there?
Any comments would be appreciated.
Ken K
Beaumont, TX
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