R? series Merc intermediate housing cutaway drawing?

[Boomyal]

Does any such thing exist? Is there anyplace in the intermediate exhaust passage that could trap a hard object and cause a rattling noise when the engine is running?

On friends 898 (R series?) there is a rattling when the engine is at idle on the muffs. The U-joints are tight, the gimbal bearing runs as smooth as a baby's behind, there is no noise eminating from the upper gear case.

All of this was examined using a stethescope. I have not heard it personally, but it is reported to be mild but significantly noticable.

 

[Don S]

Re: R? series Merc intermediate housing cutaway drawing?

It's probably the exhaust shutters. They are located in the lower part of the exhaust Y in those older setups.

Item 22 is the shutter, and item 16 shows one side of the Y pipe.

And if all else fails, read the Merc service manual..

 

[hullofalottatrouble]

Re: R? series Merc intermediate housing cutaway drawing?

this the one you are after?

http://mercruiserparts.stemtostern.com/MercBlockDisplay.aspx?DocNumber= 99964

 

[Boomyal]

Re: R? series Merc intermediate housing cutaway drawing?

It's probably the exhaust shutters. And if all else fails, read the Merc service manual..

If those are metal shutters, that is probably what the noise is. Is it normal for them to make some noise? Is that necessarily a problem? Are they supposed to be dampened in some way?

Appreciate all the help on this short notice. Have been keeping an eye out for Service Manuals #'s 1 & 2.

Maybe I should just pick up a Seloc until I can find the OEMS at a reasonable price?

 

[whywhyzed]

Re: R? series Merc intermediate housing cutaway drawing?

I'm trying to remember, I think mine were rubber bonded on to metal hinged piece...the rubber rotted off and the metal part rattled....

 

[Boomyal]

Re: R? series Merc intermediate housing cutaway drawing?

I'm trying to remember, I think mine were rubber bonded on to metal hinged piece...the rubber rotted off and the metal part rattled....

I heard the noise myself today. Am convinced that is what it is. A real tinney sound. Am told that is a precursor to falling off into the exhaust path.

 

[zshooter]

Re: R? series Merc intermediate housing cutaway drawing?

Yup, I've heard that as well. Search "exhaust shutters" and you'll find all sorts of info.

When I went to the dealer to get the shutter to replace my 1986 shutters, they couldn't find the part right away, and the mechanic stated "we just take those out and throw them away."

Supposedly, if you're not in big water alot, or don't come to a slamming halt allowing backwash to go up the exhaust passage, you can run fine without them.

New one was only a few bucks. It is rubber coated. Over time and heat, the rubber eventually rots off, leaving metal to clatter against itself under low rpm. Under high rpm the exhaust volume keeps the shutter wide open.

Have fun.