loud rattleing noise comming from rear port side

[dbhickey]

Hi,

I just did a bellows job and put my boat in the water. Prior to installing the outdrive I ran the engine and had a small rattling noise coming from the exhaust manifolds. I assumed it was the flapper valves as the noise was only when reducing power. Now that it is in the water the rattling noise is much louder and only at lower RPM's(intermittently). Seems to be coming from the port exhaust manifold or rear of the engine. No noise from the valves and all plugs where pulled and are clean.

Is it possible that the flapper valves have broken loose and are intermittently rattling in the exhaust manifold.

Any comments would be appreciated.

5.7 mercruiser with aplha 1 outdrive.

 

[Don S]

Re: loud rattleing noise comming from rear port side

Pull the risers and physically look at the flappers.

 

[dbhickey]

Re: loud rattleing noise comming from rear port side

Thats my plan for the morning. Just wondering if they would cause such a loud rattle.

 

[Bondo]

Re: loud rattleing noise comming from rear port side

Prior to installing the outdrive I ran the engine and had a small rattling noise coming from the exhaust manifolds.
Thats my plan for the morning. Just wondering if they would cause such a loud rattle.

Ayuh,.... Ya fired the motor, without water flow...

The exhaust Fried the rubber off the shutters...

That's why they're metal to metal now...

 

[dbhickey]

Re: loud rattleing noise comming from rear port side

No I ran the engine with water direct from the intake line forward of my stern. That being said it could still be possible but the problem was not until a test ran the boat for about an hour. Shut it down and tried the next day. That was when the loud rattling happened.

 

[Bondo]

Re: loud rattleing noise comming from rear port side

Ayuh,... Could be a cumulative effect... Definitely the place to look...

 

[dbhickey]

Re: loud rattleing noise comming from rear port side

Problem solved. Just had the opportunity to pull the riser and sure enough no rubber. In addition the rubber around the pin was gone. Pulled the valve out and put everything back together. No noise while running. It is hard to believe that such a loud ratting could be caused by the shutters.

Thanks