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[Rortega46]

Ken:

I changed my SW to an OB last September, and have now enjoyed the C34 two summers having put about 300 hours on the M35B.  I am not not highly technical but will gladly share my experience. 

With the SW pump, motored 400 miles and 10-12 hour days from Houston to New Orleans in water temp of ~ 60. Noticable steam in the exhaust at 2,100 rpm.  Two summer trips to the gulf coast (7-10 hours /day) in water temp of ~85 with steam in the exhaust as well. 

With the OB pump, had two summer trips to the gulf coast with no noticeable difference in exhaust compared to the SW. 

I have not measured the exhaust water temp with either pump installed.  Bottom line ......steam in the exhaust appears to be the norm and with no overheating from OB diminished water flow, I plan to keep the OB.

[Rortega46]

 I am looking back at this old post and wondering if I am being naive.  Should I plan on doing some routine /preventative maintenance to either the exhaust riser, anti-siphon valve, aqualift muffler, or exhaust hose?

[Stu Jackson]

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Should I plan on doing some routine /preventative maintenance to either the exhaust riser, anti-siphon valve, aqualift muffler, or exhaust hose?

Ray, not naive at all.

The exhaust riser is rarely an issue because the water injection through the nipple is straightforward so rarely gets "clogged" or blocked.  What does happen is a failure at the weld, which you can visually inspect regularly.

Anti-siphon valve can be removed and cleaned and the rubber duck bill replaced if you suspect any failure.

Muffler usually fails at the ports, unless you use hump hose.  Otherwise no moving parts.

Exhaust hose usually has a shelf life.  If it leaks (air, soot) replace it.

[Ron Hill]

Ray : Stu is correct that the most common exhaust failure (cracking and subsequent leaking) is that of the welded nipple in the exhaust riser.
 
I wrote a Mainsheet tech note article that pointed out that Catalina used a stuff wire reinforced hose between the anti syphon valve and that nipple in the MK I M25/XP & M35 exhaust configuration.  I believe that all engine vibrations were transmitted to the attached riser and then to that nipple - caused causing stress on that nipple weld and cracking. 
As there is no requirement (acute bend and exhaust water) to use a wire reinforced hose in that connection, I recommended using a softer nylon reinforced hose!!  This will help prevent premature cracking of that weld!!

Not too sure about the M35BC exhaust configuration?

A few thoughts

[Rortega46]

Stu & Ron, thanks for the informative and specific reply. Up to now I have been somewhat naive ignoring the exhaust system thinking I’d fix it when it broke.  Better to know what to look out for and keep an eye on things, especially since I am planing to venture further from my home port than in the past.

I’ll add the the following to my to do list for this winter and in the future.....
1. Remove, clean and inspect anti-siphon valve
2. Inspect welds on exhaust riser
3. Inspect muffler
4. Inspect exhaust hose
5. Inspect anti-siphon valve rubber duck bil
6. Replace or repair anything suspect from above inspections.  When replacing exhaust hose use nylon (not wire) reinforced hose.

Thanks again!

[Stu Jackson]

6. Replace or repair anything suspect from above inspections.  When replacing exhaust hose use nylon (not wire) reinforced hose.

You're welcome, Ray.  Slight edit here:  You NEED EXHAUST hose for that exhaust, specifically made called "exhaust hose."  It IS wire reinforced.  From the muffler to the transom.

You need silicone reinforced hose from the exhaust riser metal tube to the muffler inlet.  This short piece is what we call HUMP HOSE.

[Dale Stone]

All,
I love this org. It is very informative and sometimes amusing. I too have noticed some steam coming from my exhaust. Doesn't take much running to see it and because I can't see the actual exhaust output (I hate that about the C34II), I see a layer of steam on the water and hope there is water coming out. But as stated, the temperature is around 160F (I think) and never changes. I am new to this boat, 2001 C34II, and was going to dig into it next spring. I did change the impeller before launch, which was a PITA.

Mick,
The picture of the hose from heat ex-changer to riser was scary. I will definitely check mine. Do you think that was the reason for the steam?

Thanks

[Ron Hill]

Dale : Where you are located, the outside temp and humidity are possibly such - that steam will form.

Otherwise it is not normal to have steam in the summer.  However, spring, fall and winter you'll probably see steam!!

A thought

[Dale Stone]

Hi Ron,
I'm in New England, Salem, Mass. Interesting thought, the ocean water here ranges from 60F to 70F during the sailing season.
I have to think about how that would work. I can imagine the 160F moist exhaust just over the 65F water condensing and creating a fog layer. Very clever!

Thanks
Dale

[Mick Laver]

Hi Dale,
No, I don't think that occluded hose was the problem. I replaced all the hoses in the cooling system (fresh and raw) from the intake through-hull to the exhaust riser nipple and that was a "yikes why didn't I do this sooner?" moment. The steam issue began later when I swapped my Sherwood G-908 for an Oberdorfer N202-908.