Exhaust Shutter disintegrated? grommets?

[UNSUREBOATGUY]

1987 Mercruiser 3.0 Alpha 1

I ordered a new exhaust shutter because I was hearing an intermittent metallic noise towards the aft of the engine that comes and goes with different RPMs. After doing some searching and reading-seemed to be a reasonable guess as to what was making the noise. I was told by a previous owner that he overheated at one point, so I figured I might as well take a look. All I found was the steel rod that goes across the pipe. So, I have a few questions:

1. Do I need to take the drive off again to look for shutter parts? When I had it off this spring, I didn't see anything lodged in the exhaust outlet at the gimble. I tried to see if I could see/feel anything as I looked down the pipe tonight and wiggled a wire around in there. There is nothing that would make me think there is a blockage, except possibly the metallic noise and the fact that the shutter is completely missing. (The metallic noise may have been the piece of steel rod?) The rubber connector hoses look good-they may have been replaced. Maybe the shutter pieces were fished out before????

2. Where do I find the grommets needed to install the new shutter in the pipe? (as seen on page 6C-5 in manual # 10) The old ones were junk.

3. When I put everything back together, should I sand down the pipes to make them smooth so the connector hoses seal better?

4. Also the manual says to put bellows adhesive on the bottom pipe and connector hose where they meet. Is this a good/bad idea? I plan to follow the directions unless there is some serious reason not to. Should I put any sealer on any of the other joints? I just want to do it all right.

Thanks a bunch for your input. Sorry for the long post.

 

[havasuboatman]

Re: Exhaust Shutter disintegrated? grommets?

1, Yes, you need to find and remove those old shutter pieces.

2, Mercruiser parts dealer (I don't remember if they come with the kit, or not)

3, If you have a lot of corrosion, it wouldn't hurt sand the parts smooth.

4, I never use bellows adhesive on the manifold to down tube rubber, makes it a B@#ch to get them a part and can even cause them to be destroyed the next time you take them apart.

 

[UNSUREBOATGUY]

Re: Exhaust Shutter disintegrated? grommets?

Thank you.

After I finished the post, I found the grommets online at a few places-just had to figure out the part # first. I'll order an outdrive gasket set too and yank it and see if I can find the shutter parts. If they are not in the exhaust pipe in the gimbel, is there a spot in the outdrive exhaust passages the parts like to congregate?

 

[UNSUREBOATGUY]

Re: Exhaust Shutter disintegrated? grommets?

Any suggestions where to look first? I'd rather not take apart the drive if I can avoid it. Thanks.

 

[stonyloam]

Re: Exhaust Shutter disintegrated? grommets?

Ha! Just did that exact thing. Had the outdrive off of my 470, thought couldn't hurt to start for a few seconds. Hit the starter, fired right up, shut her off and 1/2 of the shutter was laying on the floor. Another thing to do! Got new shutter and grommets from local dealer. took it apart and promptly dropped one of the grommets down the hole. Well it worked once before, hit the starter and out it came. I did use bellows cement on only the bottom part of the lower exhaust tube. Made it a little harder to get back on, but not too bad. Seems like the only place for the pieces to be hung up would be at the forward end of the exhaust bellows in the bellhousing. If they are not there they are probably gone. Fun job!

 

[UNSUREBOATGUY]

Re: Exhaust Shutter disintegrated? grommets?

Thanks for the input. I couldn't find the pieces anywhere. I pulled the drive took a good look in the gimbel housing and where the idle relief ports are-seems to be the best place for them to get stuck. I turned the drive upside down and shook, tapped etc. Nothing. When I pulled the lower in the spring to do the raw water pump, I took a good look in the exhaust passages, as much out of curiosity as anything (I had never had a I/O apart before) and didn't see anything then. I've only had the boat out twice since then. At this point, I just have to assume they found their way out somehow, or more likely fished out by the previous owner when he cleaned up after the overheat. I don't know why he didn't replace the shutter though. Hmmm...

How big are the metal pieces in the shutters anyway? Too bad they are stainless, if they were regular steel, I have a big magnet that might have cleared this all up a lot sooner. Of course, they would rust out and cause more problems that way. Oh well.

Those little grommets were cooked. I can only imagine the PO had to replace the rubber connector tubes as well. They look pretty new. I guess when I start the boat up again after I have everything back together, I'll know whether the rattling noise that started this goose chase is gone. If not, I'll probably be back here looking for more advice.

 

[stonyloam]

Re: Exhaust Shutter disintegrated? grommets?

The shutter is oval shaped, the size of the exhaust pipe opening, and is all rubber coated metal except for the rubber hinge in the middle. So each metal piece is a little smaller than 1/2 the diameter of the pipe. With the outdrive off mine (1/2) flew right out. On mine I was able to install one grommet from the outside the other needed to be installed from the inside (of the pipe), so a paper towel stuffed inside to catch it if you drop it (like I did) is a good idea. Once I got the inside one in, I put the shutter in place and pushed the other over the end of the shutter shaft from the outside. I wet mine to make it easier for them to slide in. Have fun.

 

[UNSUREBOATGUY]

Re: Exhaust Shutter disintegrated? grommets?

Thanks for the advice. That's about what I thought about the size. I would think it would have been pretty hard for me to miss them if they were still in there. I've been searching the forum for noises similar to what I was hearing in case it was not the shutter causing the noise. I'm a little paranoid now about valve train/lifter problems now. It's probably fine, I've just got medical student disease now for boats. I should probably stop reading until I get it back together and run it to see.

 

[Simoniz]

Re: Exhaust Shutter disintegrated? grommets?

I guess the reason the manual says to use sealant on the lower pipe joint is that this joint is close to and possible under the waterline so, if the joint leaks, water comes into the boat.