Help with rattle noise on merc 3.0

[cbucner]

Hello!
I have a problem with a rattle noise on the back of the engine around the flywheel area, I guess the alpha coupler.
I did a video o the problem and you can hear the rattle noise really well.
Please download and watch it's small only 3mb.
Here's the link

http://64.65.22.75/filme/merc30rattlenoise.wmv

Do I have to take the engine out for this job or what can it be??
Thanks for any replies.
I'm really getting frustrated with this boat.

 

[cbucner]

Re: Help with rattle noise on merc 3.0

Forgot to say that the drive is out so the noise it's not coming from the drive.
Thanks

 

[Don S]

Re: Help with rattle noise on merc 3.0

Pull the exhaust riser off and check the exhaust shutter. When the rubber wears off the outside edges, the SS plate rattles against the exhaust tube.

 

[cbucner]

Re: Help with rattle noise on merc 3.0

Thanks DonS
Which one of the 3 pieces of the exhaust is the raiser?
There's one connected to the engine, one in the middle and one going down to the transom?
Thanks again.

 

[Don S]

Re: Help with rattle noise on merc 3.0

The shutter will be in the top of the pipe that attaches to the transom shield.
Item 6 is the shutter

The riser is attached to the manifold. #15 in the picture below.

 

[Bt Doctur]

Re: Help with rattle noise on merc 3.0

had trouble with the link but it might be the flywheel dust cover is cracked

 

[cbucner]

Re: Help with rattle noise on merc 3.0

It looks like that was the problem.
I removed the shutter and ran the engine and there no more rattle.
Thanks DonS
Could this shutter cause engine backfiring or bog??
Thanks again.
Where can I order this shutter ??

 

[Don S]

Re: Help with rattle noise on merc 3.0

I removed the shutter and ran the engine and there no more rattle.

I sure hope you put a new gasket between the riser and the manifold. Otherwise you will be getting water in your engine when you shut it off.

The shutter won't cause your backfire or bog, sound more like a lean fuel mixture just listening to your video. What year is your engine?

Any Merc dealer sells the shutters.

 

[cbucner]

Re: Help with rattle noise on merc 3.0

Here's the pics of the shutter, it doesn't look too worn out but again I don't know how a bad one will look like.

The engine ser nr is OL638511

How would I solve the running lean problem.
Also my alternator died too.The voltmeter gauge shows only 10v not 14v like before.
Are these fixable or need a new unit??
Thanks Don S , you're the man!! .

 

[cbucner]

Re: Help with rattle noise on merc 3.0

I ran the engine dry for about 10-20 secs.
My drive is removed so I can't connect the water ears.

 

[Don S]

Re: Help with rattle noise on merc 3.0

You fix the lean condition by adjusting the idle mixture screw on the carb.
With the cable for the throttle disconnected, and water to the drive, warm the engine to operating temp, choke fully open. Hook up a shop tach so you can see the rpms while adjusting the mixtuer.
Turn idle mixture screw in till rpms drop, then back the mixture screw out till the idle is at it's highest rpm. (may have to goose the throttle a few times to keep the engine cleared out). Adjust idle speed to 650 to 700, and recheck. Once you JUST reach highest rpm and are sure that is where it's at, open the mixture screw an additional 1/8 turn.

As far as your alternator goes, they can be rebuilt, or replaced. If you have a place that can rebuild it, it's usually cheaper than a new one if not much is wrong.

 

[Don S]

Re: Help with rattle noise on merc 3.0

I ran the engine dry for about 10-20 secs.
My drive is removed so I can't connect the water ears.

Disconnect the water pickup hose from the engine at the transom shield. Then attach your garden hose to the end of that hose. Turn on the water and you are good to go. Make sure the engine is level or front higher.

And don't forget that new gasket.

 

[cbucner]

Re: Help with rattle noise on merc 3.0

I think my choke is automatic .The boat is a 2000 yaer model.
How can I hold it open?
Thanks

 

[Don S]

Re: Help with rattle noise on merc 3.0

When you warm the engine up, to adjust the carb, it better open by itself.
Your boat may be a 2000 model, but your engine is a 1999 engine.

 

[cbucner]

Re: Help with rattle noise on merc 3.0

ok so I have to do this eary in the morning when the engine is as it's coldest so the choke will be wide open.
Got it Don .
Anything else I should check??
Thanks again.

 

[Don S]

Re: Help with rattle noise on merc 3.0

Who said anthing about doing this with the engine COLD?????
Read this again.

With the cable for the throttle disconnected, and water to the drive, warm the engine to operating temp, choke fully open. Hook up a shop tach so you can see the rpms while adjusting the mixtuer.
Turn idle mixture screw in till rpms drop, then back the mixture screw out till the idle is at it's highest rpm. (may have to goose the throttle a few times to keep the engine cleared out). Adjust idle speed to 650 to 700, and recheck. Once you JUST reach highest rpm and are sure that is where it's at, open the mixture screw an additional 1/8 turn.