Exhaust Noisy After Water Pump Changed Out

[Johnny P]

I need help diagnosing an exhaust noise that occurred after replacing my water pump in my Yamaha Outboard 2017 115 Sho. (6FNL 1007336) The engine was quiet and running well before I changed out all the fluids, filters and other service items as well as the water pump. The engine still performs well however when I start it now it is noisy and bubbles up at the front of the lower unit. No visible oil leaks anywhere and everything else appears to be fine.
At idle the exhaust noise above the lower unit is very loud. It appears there is an exhaust or air leak toward the front of the lower unit. Any suggestions?. My dealer is 4 weeks out and I am hoping this is something simple I can correct myself.

Any help would be greatly appreciated.

Thanks is advance.

John

[99yam40]

I would not think a leak that leaks exhaust out of the front of the lower unit under water would be loud,
And I have no idea where a leak like that could come from the lower unit

[Johnny P]

I would not think a leak that leaks exhaust out of the front of the lower unit under water would be loud,
And I have no idea where a leak like that could come from the lower unit

There is a lot of air coming up at the front of the lower unit and a real guttural sound. Reminds me of a Harley D at idle.

[Keithbaja]

Jeeezz ! Tilt drive up and look at the "megaphone" exhaust rubber seal. Use "Gaska Cinch" on the new one and be gentle on your upward meshing on the lwr/upper units. DONT watch utube vids for outboard repair....... U don't want the tech working on that 737 your flying to NY next week watching Ya-hoo's vids on turbine service ?????

[99yam40]

There is a lot of air coming up at the front of the lower unit and a real guttural sound. Reminds me of a Harley D at idle.

Does it have that Harley sound while the lower unit is down in the water at idle?
Does this SHO have some kind of opening on the front of the lower unit?

[Johnny P]

Does it have that Harley sound while the lower unit is down in the water at idle?
Does this SHO have some kind of opening on the front of the lower unit?

Yes, that's when it is most noticeable. When I have it out of water with the earmuffs on I don't hear it. There is an opening on the front of the lower unit near where the speed guage tube enters the unit.

[Johnny P]

Jeeezz ! Tilt drive up and look at the "megaphone" exhaust rubber seal. Use "Gaska Cinch" on the new one and be gentle on your upward meshing on the lwr/upper units. DONT watch utube vids for outboard repair....... U don't want the tech working on that 737 your flying to NY next week watching Ya-hoo's vids on turbine service ?????

I will have a look to see if I can find what you are speaking about. I'm not sure of which seal your are speaking of.

[TownsendsFJR1300]

Possibly the dampener guide/seal (#8 & #9 missing)?

https://www.boats.net/catalog/yamaha...casing-drive-2

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[Johnny P]

Possibly the dampener guide/seal (#8 & #9 missing)?

https://www.boats.net/catalog/yamaha...casing-drive-2

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The damper seal and guide are both in place. I did not remove those during the service. Thank you for the information. I appreciate it.
One suggestion I received was that the wave washer might need replacing. I did not replace it during the service just reused it. The motor only has about 100 hours on it though.

[TownsendsFJR1300]

The wave washer, on the water pump, if old, won't cause your issues..

I suspect you may and to go back in and re- check everything

[Keithbaja]

OK, here goes.. Where part 8/9 goes up into lwr case there is a exhaust rubber seal of good size. Tilt drive up and look Up into the bottom. The seal is like 3 by 4 inches sgaure.. I sea SOO many gearcases messed up because everyone thinks they can watch a utube vid and do the job correctly. NOT !! There are many tricks and items to inspect and know about. They are not written in the service manual. And also never ever use grease/oil on a impeller,.......output

[Keithbaja]

Grrrr....OUT.

[Johnny P]

OK, here goes.. Where part 8/9 goes up into lwr case there is a exhaust rubber seal of good size. Tilt drive up and look Up into the bottom. The seal is like 3 by 4 inches sgaure.. I sea SOO many gearcases messed up because everyone thinks they can watch a utube vid and do the job correctly. NOT !! There are many tricks and items to inspect and know about. They are not written in the service manual. And also never ever use grease/oil on a impeller,.......output

I will try your suggestion and get back to you. Thanks for your help!

[Johnny P]

Possibly the dampener guide/seal (#8 & #9 missing)?

https://www.boats.net/catalog/yamaha...casing-drive-2

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I pulled the damper seal and guide, cleaned and applied a slight amount of grease and re-installed then torqued the center bolts first on the lower unit and all is well! Thanks for pointing out the damper seal to me! Who would have thought it could make such a difference!

[TownsendsFJR1300]

Glad you got it fixed!