exhaust riser replacment

[cmainprize]

When I was cleaning out the HX last week I noticed some dampness aroung the exhaust flange.  I pulled back the fiber wrapping to get a better look and guess what.  The exhaust riser has been welded to the flange.  I assume it leaked exhaust gas at some point and instead of using muffler cement someone welded it.  The gasket area only showed a little dampness with no obvious leaking so the job will be added to my fall projects list when I haul the boat in six weeks. 
The weld job looks solid but I can't live with it.  I noticed catalina direct sells stainless risers.  My question is this, is it worth it to get a stainless riser made or should I just replace what's there and make one from black pipe?  The boat is in fresh water.  Obviously I need a new flange as well.

The PO is a friend who bought the boat new and he swears he did not have it welded.  He actually came over to look at it and had no idea.

Cory

[Stu Jackson]

Cory, this FAQ includes just about all the options available for rebuilding or rebuying.

http://www.c34.org/faq-pages/faq-exhaust-pipe.html

How you choose to do it is up to you.

[Ron Hill]

Cory : Disregard the site that Stu mentions.  
You are the first MK II with an M35BC engine (that I know of) to have a exhaust riser problem.  All of the data on our site applies to a M25/XP engine and your exhaust system is very differant!

Your flange on the riser should be welded to a piece that is circular and mates to an identical piece on the engine exhaust manifold (with a gasket inbetween).  The two circular pieces are held together with a special circular grooved clamp.

I'd contact Catalina and I'll guess that they will tell you to ship them your leaking piece so they can make a replacement.  
I wouldn't go "cheap charlie" as exhaust fumes can be dangerous.   A few thoughts  

[John Sheehan]

Cory,

Carefully check the raw water connection to the riser.  On our 2003 the clamp had become loose so I tried just to tighten the clamp but that didn't work.  Then I cut off about one inch of the hose and re-clamped it  No more leak.  Hope it works for you.

John

[cmainprize]

Thanks Guys
The leaking I was referring too is antifreeze from the manifold to flange gasket.  It does not leak exhaust gas from the riser.  I tested it with a mutigas detector from work.  (Fire Dept.)  My only reason for considering changing the riser is because it is welded to the flange and I do not think this is correct way to install it.  I am one of those people who fix things before it's broken.  When I pull it apart to change the gasket I will be able to get a good look at what was done.

[John Sheehan]

Cory,

Your riser sounds OK.  They are welded to the flange on our boats.  Either the manifold has a problem or you may be getting a leak from an antifreeze hose dripping down.

John

[cmainprize]

Perfect, Sounds like a $4.00 gasket and I am good to go.  I had no idea they were welded from the factory.  I was comparing it to my m25 that was threaded only.  The members here sure know there stuff.

Cory

[Ron Hill]

Cory : You have me confused. 
Looking at your posts with John, I assume that you are talking about the raw water exhaust water coming out of the HX and entering into the nipple on the riser???  Not the antifreeze from the internal (closed fresh water/Prestone 50%) coolant system??   

[cmainprize]

Sorry Ron
I made a reference to the HX because that's what I was cleaning out when I noticed the antifreeze leak at the exhaust flange.  I was fishing for impeller pieces and changing the zinc when I noticed the leak.  Thats when I noticed that the riser was welded to the flange and thougth someone had done it to solve an earlier problem but apparently that's how they come from the factory.  I was compairing it to my old C30 with the m25.

Thanks again
I always look forward to your posts on the various topics, your opinion always seems like the best way to go.

Cory