Catalina 27 exhaust hot section failure

[twwood911]

I replaced the rusted original hot section on my '82 Catalina 27 universal 5411 in 2020 with a Moyer system that is a perfect fit and a very easy solution. Unfortuntely, it sheared at the nipple adjacent the exhaust flange this past summer. (see photo) I have so far been unable to remove the nipple from the elbow with 18" & 24" pipe wrenches, even after soaking it for days with penetrant and WD40. Has a sealant been used on the joint that is making this so difficult? Also, the strut/support from the transmission to the upper loop of the hot section had not been reconnected when the marina replaced the engine in 2011 when I bought the boat - a forum indicated it wasn't necessary, so I did not replace the strut in 2020, which may be why it has recently failed(?). I plan to install the strut this time - where should I connect it on the transmission, ie. is there a specific bolt to use or avoid?

[joe_db]

Isn't this the third time this thread has been started?
In the last thread it was advised the diesel vibration will cause the exhaust to break, the strut is needed.
It was also advised that union is probably not a good idea.

[twwood911]

Catalina 27 exhaust system failure

Thanks so much, Joe DB. I attempted a prior post but inadvertenetly closed it prior to receiving/seeing any responses (novice...), so yours is the first and only response I've seen. Have you any advice for removing the broken nipple or how to attach a strut to the Moyer replacement system shown? Thanks.

[ndutton]

Please see this thread.

[joe_db]

https://www.moyermarineforum.com/forums/showthread.php?t=12564

There was the second thread.
Anyway, someone with a welding torch might heat the exhaust and get the broken union off of it. Don't use one of those again

[hanleyclifford]

A stuck nipple of this type requires extra care and aggression. Lay it out on a concrete floor with the matching pipe wrenches in position. Then use well pipe "cheaters" on both wrenches, up to 3 feet in length. The nipple will give.

[twwood911]

Catalina 27 exhaust hot section failure

Thanks so much to all of you for your helpful comments - this forum is great. FYI - the observation about my engine vs a 5411 is interesting and correlates with my suspicion. The marina replaced the engine (at seller's expense) with a reman when I bought the boat in 2011, so I didn't get to see the original 5411 - all I knew is that the original was copper-colored and the replacement is silver. I've noticed minor alignment issues, the lack of original exhaust strut alignment and a different exhaust flange. The flange provided by Moyer with their new hot section in 2020 did not fit my manifold, so I reused the original flange and union assy. It's a Kubota Z-series, but I understand there were slight variations within the series, which may explain the differences from the original 5411 in the boat. Again, thanks so much, guys - with your help I think I'm set to repair and correct the problems.

[joe_db]

Thanks so much to all of you for your helpful comments - this forum is great. FYI - the observation about my engine vs a 5411 is interesting and correlates with my suspicion. The marina replaced the engine (at seller's expense) with a reman when I bought the boat in 2011, so I didn't get to see the original 5411 - all I knew is that the original was copper-colored and the replacement is silver. I've noticed minor alignment issues, the lack of original exhaust strut alignment and a different exhaust flange. The flange provided by Moyer with their new hot section in 2020 did not fit my manifold, so I reused the original flange and union assy. It's a Kubota Z-series, but I understand there were slight variations within the series, which may explain the differences from the original 5411 in the boat. Again, thanks so much, guys - with your help I think I'm set to repair and correct the problems.

The Moyer flange is for a gasoline fueled 4-cylinder Atomic 4 engine, so it would not fit a diesel engine of any kind unless by random chance. This issue was not caused by variations in the version of the 5411.
Also it looks to me like the union is not necessary, I would not use it at all if it can be avoided. Make sure and add a brace as well, the diesel will vibrate a lot more than the Atomic 4 does.