Exhaust noise from botom transom Mercruiser Alpha 1

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Ross2

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I everyone,

We own a Rosborough RF-246 1996 with a inboard / outboard Mercruiser 3.0 liter , Alpha 1 sterndrive. Question is , is it normal that the Exhaust exit at the bottom of the transom ( left and right side ) which is about 1 inch above the water line. That makes a loud exhaust noise. I don't know if the exhaust normaly exit that way or it should exit through the center of the prop. Please help ..... Thanks

When the boat was out of the water , i turn the engine on the the exhaust was comming out from the 2 holes at bottom of the transom, No exaust was comming from the center of the prop. If the bootom of the transom was in the water it would not make noise be the problem is that the transom is about 1 inch above the water line .... :)
 
Don S

Don S

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Re: Exhaust noise from botom transom Mercruiser Alpha 1

It's normal, they are idle relief ports.
 
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Ross2

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Re: Exhaust noise from botom transom Mercruiser Alpha 1

Hi Don,


Thanks for the answer. But is it normal that the exhaust releif port are aboved the boat water line or the engine and transom are set too high ???. Also when cruising does all exhaust should go to the prop or a pourcentage will still go throw the exhaust releif port.

Thanks
 
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flabum

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Re: Exhaust noise from botom transom Mercruiser Alpha 1

The releif ports normally are under water, I have seen few boats that float high enough to expose those ports. If there is no exhaust comming out of the prop, the exhaust bellows may be broken or fallen off.
 
BAYLINER185

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Re: Exhaust noise from botom transom Mercruiser Alpha 1

The manifolds should have the Y pipe that will send the exhause through the prop. Im not sure if you have that or not with this set up as to me it sounds like you have through hull exhaust and not through prop exhaust. If thats the case NO exhaust wil lcome through the prop.

Im not sure if through hull exhaust is the same as what Don S said you have as having exhause ports. If the releife ports are something other then the actual exhaust "pipes"
 
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flabum

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Re: Exhaust noise from botom transom Mercruiser Alpha 1

BAYLINER185 said:
The manifolds should have the Y pipe that will send the exhause through the prop. Im not sure if you have that or not with this set up as to me it sounds like you have through hull exhaust and not through prop exhaust. If thats the case NO exhaust wil lcome through the prop.

Im not sure if through hull exhaust is the same as what Don S said you have as having exhause ports. If the releife ports are something other then the actual exhaust "pipes"
Click to expand...

Ahhhhhh we never assume thru-hull the way he described it..... good observation!


Would like to see a picture of the back of that boat.
 
Don S

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Re: Exhaust noise from botom transom Mercruiser Alpha 1

From what I see in a quick google search, the boat is a trawler type hull, not planing. Which is good since a heavy 24' boat isn't going to go fast with a 3.0L Mercruiser and an Alpha dirve.
Even with a planing hull the idle relief ports are above the water. But at trawler speed they are normally "Below" the water line on planing boats.
Either way, water and exhaust are going to come out of them. The idle relief ports are cast into the transom shield into the exhaust.
Water and exhaust WILL take the path of least resistance.
 
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Ross2

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Re: Exhaust noise from botom transom Mercruiser Alpha 1

Thanks you very much for all answers. For the pictures i have none and the boat is in storage 100 miles from my house. Now the question is ... Is there any adaptor to extend the 2 Exhaust relief holes to bring them 2-3 inch below the water line.

Thanks
 
Don S

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Re: Exhaust noise from botom transom Mercruiser Alpha 1

No extensions I've ever heard about
 
Bondo

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Re: Exhaust noise from botom transom Mercruiser Alpha 1

Is there any adaptor to extend the 2 Exhaust relief holes to bring them 2-3 inch below the water line.
Click to expand...

Nope,........

But you might be able to Build something that'll work.........
 
Haut Medoc

Haut Medoc

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Re: Exhaust noise from botom transom Mercruiser Alpha 1

Ross2 said:
Thanks you very much for all answers. For the pictures i have none and the boat is in storage 100 miles from my house. Now the question is ... Is there any adaptor to extend the 2 Exhaust relief holes to bring them 2-3 inch below the water line.

Thanks
Click to expand...
You could probably rig something up cheap with some PVC & JB weld.....;)
 
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