3.0L exhaust shutter question

[trevtt600]

Have a 1989 Wellcraft with Mercruiser 3.0L, alpha 1 outdrive. Motor is actually a 1978 though. I have what sounds like a rattle of some sort coming from the back of the engine down by the drive shaft. I was looking on iboats lastnight and saw that the exhaust shutters can cause quite a ruckuse when they go bad. Is the same thing true with the mercruiser 3.0 exhaust shutter? It only happens around 2000-2300 rpm. Motor was just replaced by myself and aligned by a mechanic.

 

[tschmidty]

Re: 3.0L exhaust shutter question

Yep, the exhaust shutter can do that.

 

[imported_TheMan]

Re: 3.0L exhaust shutter question

Could it be? Sure. It could also be an assortment of other things (ignition coil rattle, loose shift components, etc.) Do the ol' ear/screwdriver/area test to pinpoint your rattle.
I don't have my 3.0L anymore, but I believe the shutter should be at the top of the exhaust pipe near the riser. Put your long handled screwdriver tip at a point near the top of the exhaust pipe and the handle to your ear and listen to see if that is it. If it isn't a loud rattle at that point, keep looking.

It wouldn't be a bad idea to just pull the riser off and check the flapper anyway... so if you feel like doing it, go for it.