Installing thru hull exhaust on a 400ss


C

CaptSteve

New member
I have an offer on an 03 400ss with 8.1ho's and it does not have thru hull exhaust. Has anyone ever converted their exhaust to thru hull? What manufacturer is recommended? I'd like to have the silent choice feature. Any advice would be appreciated. Thnx!
 
I converted my my Baja, Was a pretty straightforward project. I used the Mercruiser stuff. Found the measurements for the holes online. That was the scary part... drilling 4 inch holes in the back of the boat. After that, pretty easy, mounting the air pump and wiring it up. Everything must be double clamped. My 400 had it and was removed by previous owner, I'm in the process of making it switchable again, but its just a replacing missing parts project.
 
Installed diverters on my 27PC, and as Dys mention drilling the holes is the part that needs to be pretty close. When repowering I had to move the holes up about 2 inches and remove the diverter and used turn downs. You will need 4 1/8 inch holes for 4 inch exhaust. I had two hole saws cut and welded together to cut the holes so it could be cut thru it one cut.

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I drilled a small pilot hole, mostly to make sure everything was where I measured it to be. Then drilled from both sides.
 
Great. To his benefit, I was the first offer on it and all he needed to do to get it, was beat my offer. The $90k was too close to book value for me to go higher on a boat I couldn't sea trial.
 
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