How to Diagnose Bad Exhaust Shutter

[merlin696]

I have an 89 Sea Ray with an Alpha One Drive. I have got a Medium Clunking/Knocking/Banking sound coming from the back of the engine, The sound does not get louder if you turn the wheel (I have also checked the Gimbal Bearing) and the engine is in alignment as well. The sound is heard at idle, once the engine is about 1500 RPM or so, the sound is gone. Engine Purring like a kitten. When on muffs the sound seems to come from the back of the engine IN the engine compartment, if you get out of the boat and go to the back side you cant hear it at all, just sounds like a running engine (glub glub glub glub ) It does seam that the noise does coincide with the glubs of the exhaust as well.

On the 4.3L do I need to take the engine out to get to the shutter?? I have the exhaust schematic and it doesn't look like I will need to.

If thats the case when I pull the elbow will it be right out obvious if it is bad?

I was hoping to find a youtube video of someone with a broken one so i could compare noises does anyone have a link? or maybe a picture?

Finally does this issue even sound like it would be an exhaust shutter problem? I am willing to take all ideas because I dont want to throw any more money trying to find the funny noise.

 

[Don S]

Re: How to Diagnose Bad Exhaust Shutter

Yep, pull the riser. The shutter is right in the top of the Y pipe.

 

[merlin696]

Re: How to Diagnose Bad Exhaust Shutter

For the Record, this Year the Acronym B.O.A.T is living up to its name, 10 bucks at a time! :facepalm:

 

[merlin696]

Re: How to Diagnose Bad Exhaust Shutter

Here is left bank and right bank shutters are they bad? could they be making the noise im hearing? are they suppose to be spring loaded?

 

[Don S]

Re: How to Diagnose Bad Exhaust Shutter

Look at both sides, the lower shutter on each has the rubber coating missing on the upper most shutter. The noise if form that uncoated shutter hitting the exhaust tube. Metal hitting metal ya know. At higher rpm they just stay open.

 

[merlin696]

Re: How to Diagnose Bad Exhaust Shutter

So you think that what I am hearing seeing as i ruled out the major key items, and you would replace them if you were me?

Second the part that whole sale marine has does not look anything like the ones in there currently. any idea on a pn?

 

[Don S]

Re: How to Diagnose Bad Exhaust Shutter

First: I can't hear it, so can't say for sure.
Second: you come to iboats that furnishes you a free place to find out how to fix your boat, and then buy parts at WS marine? Shame on you. http://www.iboats.com/Mercruiser-Wa...5020630--session_id.622149068--view_id.268813

 

[merlin696]

Re: How to Diagnose Bad Exhaust Shutter

no no, I buy from Iboats, but WS Marine is easier to lookup parts.. but that still doesnt help me pick the right one...

I believe based off my serial no i need the 18-2732-9

my Engine SN is OC528797

 

[mark1905]

Re: How to Diagnose Bad Exhaust Shutter

First: I can't hear it, so can't say for sure.
Second: you come to iboats that furnishes you a free place to find out how to fix your boat, and then buy parts at WS marine? Shame on you. http://www.iboats.com/Mercruiser-Wa...5020630--session_id.622149068--view_id.268813

Ouch. I'd have to say that's the first time that I've seen a verbal smackdown for mentioning a different parts vendor than iboats. Seems to happen all the time around here.. I know I'm very guilty of it.

 

[Pete104]

Re: How to Diagnose Bad Exhaust Shutter

You can do whatever you want but they have updated "shutter assemblies" available.