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Mercruiser Noise Power drop off

N

neversummer

Regular Contributor
"Hello,
I have a 1989 Maxum w

"Hello,
I have a 1989 Maxum with a 5.0 litre, 220 HP mercruiser I/O. Engine starts and runs smooth, great all summer and then the past month or so engine has been making this clicking, crackling noise at idle. Otherwise engine runs smoothly without vibration so I thought nothing of it. However after running at full throttle for a while especially after a sharp turn, the boat will begin to lose speed and the engine clicking noise will become very loud. The boat will return to full power/speed if I back down off the throttle and then open it up again.

Any thoughts?

Thank you"
 
"engine clicking noise&#34

"engine clicking noise"

Checked your oil lately? What brand of oil and filter are you using? A clearer description of the noise would help. Is the noise steady and rythmic when it happens? Coming from the valve train or the block? Put one hand on each valve cover when it clicks and see if there is a difference.
 
"I'm having a similar prob

"I'm having a similar problem with a newer version of the same engine. I have a 2003 5.0 litre carbed Alpha. I started noticing the noise a couple of years ago. At that time, it was barely noticable, but as time went on it got worse and worse. The noise I'm hearing seems to be coming more from the starboard side of the engine. It also seems to be coming from the top of the engine rather than underneath. When I first heard it, I thought valve train, but I had the boat in last year to have it looked at and the dealer said something about a 'flapper/valve' that is part of the cooling system being the source of the noise. They said it was nothing to worry about and that was that. I'm not sure I believed it at the time, but they had a chance to ring up a big repair bill and they chose not to. But throughout this season, it has gotten worse, so I'm trying to figure it out myself. The noise sounds like a rythmic mechanical noise. Besides the noise, the engine runs flawlessly. I'm not experiencing any power loss that I can tell. The engine is very well maintained. New Mercruiser oil and filter every season, new plugs this year, new fuel filter every year... you get the idea. I'm winterizing today and I'm going to try and shoot some video and upload it if that would help any experts. Thanks for your time."
 
"The dealer is talking about t

"The dealer is talking about the exhaust shutter that closes off the exhaust momentarily if your exhaust injests a backwash from a quick stop. It is located at the top of the exhaust down pipe. Pull the rubber exhaust coupler and you'll see it. It's a $20-$30 part and easy to install. Replace them in pairs on a "V" engine.
See below item #7. Part # is for a 2001.

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=809500%2099&ivar=images/C OMMON/14171.png&inbr=4856&bnbr=290&bdesc=Exhaust+System"
 
John;
Its relatively easy to

John;
Its relatively easy to pull the rubber couplers and the down elbows from the back of the engine. Then the flappers are at the top of both sides of the Y pipe. There are 16 big band clamps to undo.
After a while flappers lose rubber and you can get the metallic sounds you describe.
They are easy to change.

Rod
 
"John;
Here is what new flapp

"John;
Here is what new flappers look like.

Rod

220708.jpg
Flappers
 
Easy to change?
Before I woul

Easy to change?
Before I would make that statement I would want to see the installation. I'm sure all would agree that things can get pretty tight. I have seen a few where I would swear that they built the boat around the engine.
 
"[b]"Easy to change?"[

""Easy to change?"

Ayuh,...

It's a piece of Cake,...

After you remove enough of the boat to actually reach those 16 band clamps with a screwdriver......
angry.gif
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"
 
Allan & Bondo;
Yep; you g

Allan & Bondo;
Yep; you guys make a great point.
On my boat they happen to be fairly easy to get to. Not all are of course.

Rod
 
"I really appreciate all the a

"I really appreciate all the advice. This forum is great. I think I'll need to take the Sawzall to the back of my boat before I can get to all of the hose clamps but, that'll have to wait until next season. I just put her in storage for the winter."
 
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