Hey David, I replaced my riser back in 2023 when I did the transmission. In my case, I removed the riser to get the transmission out and the injection elbow was not clogged, but I wanted to replace the threaded nipples while I had it off. My friend used a torch to try and break the bond, and in the process, we broke the riser casting instead of loosening the nipple. We made holes in the casting. I think there were two versions, cast iron, or cast aluminum. The iron one was out of stock and only the more expensive aluminum was available. Bought the aluminum one and replaced all the nipples with stainless from a plumbing supply, never sieze on everything. I was impressed by the engineering involved as it's very well thought out. The water enters the riser into it's own chamber and is directed away from the engine and the water cools the metal before mixing with the exhaust gasses. The entire riser helps absorb the heat from the gasses and transmit it to the water, all before it goes down the exhaust hose toward the muffler. I got the part number from Catalina website and searched for that and found the product from an exhaust riser manufacturing company, online. Our riser is used by many different engines. Good luck. Chuck S
> On 06/07/2025 9:21 AM EDT David Knecht via CnC-List <cnc-list@cnc-list.com> > wrote: > > > In my raw water cooling issue that you all have been helping me with, I now > know that water comes out of the heat exchanger at a high rate, but little is > coming out of the exhaust riser. Thanks to all for helping do the right > tests to isolate the problem. I presume that means that the riser is blocked > in some way. I know that this is a frequent occurrence on Yanmar's, but I > have not heard of it on Universals (M4-30). Have others had to deal with > this? I have not been able to completely remove the riser yet to see what is > going on inside (one stuck nut). > > 1. Have others had to replace the riser on a Universal? > 2. Can they be unblocked or does it need replacement? > 3. I have not yet found a replacement online, but have multiple queries out > to Universal parts companies. It looks like it may be hard to find a > replacement. > 4. I see on the Catalina site many people cobbling together a riser using > black iron pipe parts. What they are building would not fit in my boat so I > am wondering how others dealt with this issue. > > David Knecht > S/V Aries > 1990 C&C 34+ > New London, CT > [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.
