Manifolds and Risers on Mercruiser ECT engines


L

LaserK04

New member
Has anyone here done manifold and riser replacements on a big block ECT Mercruiser (I have 8.2 MAG's), particularly the single cat versions?

I am about to embark on this project, and I am worried about the sheer weight of these things coupled with nearly impossible access on my 350ss, other than the starboard side of the starboard engine. Anyone who has done this and has any advice, please chime in!

Greg
 
Hello Greg,
I have a 2012 350SS with 8.2 MAG HO ECT, but mine have the Triple Catalyst collector cans. Just changed out my port side, STBD engine exhaust manifold and collector can. As you mentioned, both of these pieces are quite heavy. The collector can on top of the manifold is pretty straight forward. The key to removing/replacing the exhaust manifold is to fabricate two (2) "manifold alignment studs". I went to Home Depot and bought two 3/8 inch x 4 inch SS hex bolts, then cut off the hex head, then cut a notch in the end to accept a flat head screwdriver.
After removing the #2 and #7 bolts, screw in these alignment studs. Then, when you remove the other bolts, these will help hold the manifold in place. Same with installing the new one, will also hold the gasket in place. Had to remove the electric RAM for the engine hatch and the oil filter bracket to get to all. Not for the faint of heart, but doable. Feel free to reach out to me for more info.
 
I agree with Schatley, the alignment pins are 100% critical, and easy to make. It's impossible without them, and pretty straight forward with them.
 
Also, use racheting straps on each manifold slung to a 2x4 x 4' across the top of the engine. It will hold them in place as you remove the bolts. After cleaning up the old gasket and making the alignment pins as described above, you can put the gasket in place, use 2 of the shorter engine bolts to hold in place and then guide it up on using the alignment pins and the racheting straps to hold it while you start some of the bolts. PM if you want to talk through this. I did this procedure on my 350CBR last December on the 8.2's with the single cats on each side. I have also talked other forum members through the procedure and what I recommend on the poppet valves too.
 
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