Redesigned Exhaust Shutter Fitment

[Volphin]

Hi everyone,

I went out to piddle on the old '89 4.3L and get her put back together last night. I found some brittle exhaust tubes so I have bought replacements. My old exhaust shutters were not even in there so I bought new ones as well. The problem is, these newer style shutters don't fit the exhaust Y very well. They are kind of tight and don't move freely. The local dealer I bought them from said I might have to trim off the plastic nibs that would normally fit in the Y mounting holes. It just seems that the shutter itself needs trimming too. Has anyone else experienced this?

V

 

[Don S]

Re: Redesigned Exhaust Shutter Fitment

Yes, they can be a pain some time. I think part of it may be the casting process of the pipe itself and they get slightly distorted sometimes. I have had the new style fit fine in one side, and need some trimming to get in the other side.

 

[Volphin]

Re: Redesigned Exhaust Shutter Fitment

Yes, they can be a pain some time. I think part of it may be the casting process of the pipe itself and they get slightly distorted sometimes. I have had the new style fit fine in one side, and need some trimming to get in the other side.

Thanks for the reply Don. Did you have to trim the actual shutter too? The nibs I can remove easily... do I just use some scissors to trim the edges of the rubber shutter itself?

 

[Don S]

Re: Redesigned Exhaust Shutter Fitment

Only once did I have to trim anything on the shutter, and that was one side of one set of shutters. The nibs shouldn't have to be cut off. Those are the pivot points. Make sure all the corrosion is removed and the square holes for the nibs is clean. If lined up right, they should fit in the holes,

 

[Volphin]

Re: Redesigned Exhaust Shutter Fitment

Just a note to finish this thread off. I have an older boat (89) 4.3L. The new, redesigned MerCruiser shutter nibs did not reach my Y pipe holes. But they are designed with a tapered neck that fits snugly into the Y pipe. I trimmed half a nib on each shutter assembly and they fit perfectly into the Y. If your shutters don't move freely, trim one nib a bit more and retry. If they don't move freely then it is in there too tightly.