98 Johnson 90 HP Exhaust noise

[ajs584211]

I just launched my 17' CC with a rebuilt 98 Johnson 90HP motor. I can't believe how much louder the exhaust note is than my previous 91 Johnson 90HP motor. They are both 20" motors but the new one seems to be venting at least some of the exhaust out thru 2 horizontal "slits" in the lower housing well above the prop rather than all of it thru the prop? <br />Question: Is this normal exhaust venting in this newer motor or is something screwed up in the re-build? My noise problem seems to stem from the fact that at certain stages of acceleration and running, these slits are not well covered (muffled) with water and it's just much noisier.<br />As a side note I did install an aftermarket set of "dolphin fins" to the engine to help get it up on plane faster but I can't see these necessarily pushing water away from these exhaust slits. <br />Appreciate any thoughts you might about the situation...

 

[Dhadley]

Re: 98 Johnson 90 HP Exhaust noise

Welcome!<br /><br />There should be a lower inner exhaust tube. If it fell out when they replaced the pump they might not have replaced it. That could account for your noise.

 

[ajs584211]

Re: 98 Johnson 90 HP Exhaust noise

Thanks a ton for your response.<br />Sounds feasible to me.<br />Seems like these slits were really meant for water intake, not exhaust, and if that pipe is missing then the exhaust just finds its way thru these slits.<br />Do you have any thoughts about what damage I could have done running the motor with this innner pipe missing?

 

[Dhadley]

Re: 98 Johnson 90 HP Exhaust noise

Thats part of the water exit path. I doubt any harm was done.<br /><br />Just make darn sure they have you running Champion plugs and 87 octane.<br /><br />Good luck!

 

[ajs584211]

Re: 98 Johnson 90 HP Exhaust noise

Thanks very much for the help....