Mercruiser Exhaust Tube vs Exhaust Bellows Opinions, and Part # for Tube.

1985 Century Mustang

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Mar 9, 2023
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Does anyone here have knowledge/input in using an exhaust tube over a regular exhaust bellows? Pros and Cons. I'm kind of leaning towards the exhaust tube. However I heard it could be loud,,, is it that much louder? If I go with the exhaust tube , can you post which part # or tube i would need. I have a 1985 Mercruiser Alpha One Gen One 3.0 - 140hp.
 

Pmt133

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Jan 6, 2022
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On the V6 and V8 it isnt that bad. My 3.0l was loud already and it was loud loud with the tube only. :LOL: to put it another way, you could always tell when I was coming or going.

Cons, its a bit louder.

Pros? No messing with exhaust bellows. Its easy to install. Did I mention no messing with exhaust bellows? Sounds cool if you're into that sort of thing.

78458a1 I think is the oe number. All the drives use the same tube if memory serves.
 

04fxdwgi25

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Mar 25, 2022
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Only downside of the tube is that if your engine doesn't run correctly (rich / lean or burn some oil), the tube will allow a film yo form on drive unit and the rear of the boat and a very slight increase of sound. Whereas the bellows directs it all thru the prop. The 4 cyl probably will sound a little odd , but on a big block V8 it sounds nice. IMHO.

I've only used the tube for past 15 or 20 years
 
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ScottinAZ

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Jun 25, 2009
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the exhaust bellows is no fun to replace on a Merc drive... The tube is no louder nor more "messy" than a slightly torn/weatherbeaten exhaust bellows... once its in the water, it doesnt make a whole lot of difference once underway... at the dock, its slightly louder...
 

ScottinAZ

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Jun 25, 2009
Messages
856
Only downside of the tube is that if your engine doesn't run correctly (rich / lean or burn some oil), the tube will allow a film yo form on drive unit and the rear of the boat and a very slight increase of sound. Whereas the bellows directs it all thru the prop. The 4 cyl probably will sound a little odd , but on a big block V8 it sounds nice. IMHO.

I've only used the tube for past 15 or 20 years

the 4 cyl through a tube doesnt sound too bad... its not like a Honda with a FartCan on it, but its no V-8 burble either.... :D
 

tango13

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Mar 10, 2015
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I had the tube on my old 5.7 and it sounded great - ended up doing the same on my 7.4 - mechanic recommended it while he was doing some other service on my B1. Both were noticeably louder.

Its all preference, I personally like noisier boats but I know others really dont!
 

JonBoat55

Seaman
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Aug 26, 2019
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I had the tube on my Merc 3.0 for three seasons until I did all the bellows at once, so I re-installed the exhaust. I like it being slightly quieter, not a huge difference. Interestingly enough, I think I can feel a slight rumble/vibration through the steering wheel now since the exhaust is being directed through the outdrive again. I dont remember feeling that with the tube.
 
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