David, While I have not had the issue personally, when reading up on the Atomic 4 (different engine, I know) I came across a discussion on metal mufflers having internal baffle failure causing flow blockage. So I believe that is worthy of consideration.
If I recall correctly, the issue was incomplete draining the muffler during winterization which due to freeze thaw fatiguing the baffles. Coupled with normal use leading to failure. I'll dig around and see if I can find the original discussion. Good luck, Karl Karl Kuzis C&C 29 Mk 1 FIREFLY On Sun, Jun 22, 2025, 2:56 PM David Knecht via CnC-List < cnc-list@cnc-list.com> wrote: > Thanks Richard for the Nut Splitter suggestion. That is not a tool I have > ever heard of, but I intend to give it a try and see if it works. > > I am stuck again on this project and really need more of the excellent > input I have gotten previously. I got the exhaust riser off and was able > to order a new one. It arrived yesterday and I attempted to compare its > function to the old one. I can't convince myself that the old one is the > source of the problem. If I run water from the sink faucet into the input > port where the raw water would enter, water comes out the back (where it > would go to the muffler) in both the new and old exhaust riser. I can't > see an obvious difference in flow rate between the two. Is there a better > test or is this not meaningful? Obviously, I am going to install the new > one, but I am unconvinced it is going to fix the problem. The only thing > left in the system is the muffler. I have not heard of anyone replacing > this due to blockage. I thought that tended to occur at the exhaust riser > instead, but I have found online discussions of a blocked muffler > possibility. But most of the people I see replacing their mufflers are > stainless steel ones where they begin leaking. That is not my problem. I > checked all the hoses rearward of the muffler and all look good, so it > seems my problem is either the riser or the muffler. Are there any > diagnostics I should do or just go ahead and replace the muffler at the > same time as the rest is apart and pray. Thanks- Dave > > David Knecht > S/V Aries > 1990 C&C 34+ > New London, CT > > [image: pastedGraphic.tiff] > Your contributions help pay the fees associated with this list and help to > keep it active. Please help by making a small contribution using PayPal > at: https://www.paypal.com/paypalme/stumurray All contributions are > greatly appreciated.
Your contributions help pay the fees associated with this list and help to keep it active. Please help by making a small contribution using PayPal at: https://www.paypal.com/paypalme/stumurray All contributions are greatly appreciated.
