Replacing the exhaust hose - Mark II

[Jeff_McKinney]

Sorry for being away for so long, and hope everyone is OK.

I just noticed a small water leak from the top side of the bend of the big exhaust outlet hose just before it turns down to the through-hull. (not the hump hose). Since it is up in the port rear locker, I can't really see how big it is, but feels small so far. I expect the interior damage is more extensive from the hot gases. I would want to fix this ASAP before going out again. This looks like I should be able to replace it myself, but need advice on the part. My boat is a 2005 Mk II WK with an M-35B engine

I've tried searching in the forum and archives by "exhaust outlet hose", "exhaust hose" and "aqualift muffler hose" but am not seeing the info I need.

1. Suggestions for a better search term?
2. Source for the hose (Catalina, others)
3. Type/size of hose needed
4. Approximate length
5. Any precautions (other than not getting stuck in the locker)?  

You can also email me directly at jmckinney10 at verizon dot net

Thanks

[Craig Illman]

Jeff - to answer one or two of your questions, http://www.catalinadirect.com/index.cfm?fuseaction=product.display&Product_ID=1091

I remember rumors of 17 feet in length, but other recommendations to measure what you have. I need to do the same next fall.

Hope this helps.

Craig

[Stu Jackson]

Jeff,

I agree with Craig.  1-5/8 inch it certainly is, and I recall the length of about 17 feet.  I had leaking on that hose just above the muffler under the head sink.  What it did was cut the first few feet out, bought a short length of new hose and connected the two of them with a fiberglass coupler, MMC EL-158-0045 45 deg. 1 5/8", don't have the manufacturer's name handy, but I think there's only one who makes these things in various sizes, and angles.  It's Centek - I got it locally, available at Defender, too.  You could try replacing the broken piece as I did until you get to the whole replacement.

There should be a chandlery closer to you than Catalina Direct that carries exhaust hose.  Since it is so expensive, don't forget to get the extra foot, not the short foot!

There hasn't been, to my recollection, a discussion about this in the detail you've examined, so while your search phrases were great, there just wasn't anything to catch.

[Jeff_McKinney]

Really appreciate the quick response. 

Because the hole is at the top of the curve, I don't know that putting in a straight connector would even be possible.  Might as well buy the whole thing and do it once.

WM sells a 1 5/8" ID synthetic rubber hose with wire for $9.39/foot (~$170 + tax for 18 ft). Should I add in more length than that?

Will also get new 316 stainless hose clamps (2 at each end) unless other choices (T-bolt) are deemed better.

Anything else I'm forgetting?

Thanks

[Stu Jackson]

Jeff, those connectors are made in straight, mine was 45 degrees, and others are 90 degrees (not recommended for an exhaust hose).  Just thought of it as idea prior to a full complete replacement.  Check the condition of the thru hull while you're there.

[Jeff_McKinney]

Stu,

Unless they have curved connectors with an 18" radius, I'd be concerned that splicing a new chunk at the top of the arch probably wouldn't be a great choice due to increased turbulence at the two connectors. Thanks for the tip on the through-hull. The exterior of it looks OK (original but only a few years old), and hope the inside segment is also good.

I'll post a follow-up and some photos when I'm done.

[Jeff_McKinney]

OK gang: The good news is I was able to replace the exhaust hose, the through-hull looked OK, and all is good to go now. 

Turns out there was 3 mm hole that had eroded through from the interior at the top of the hump just before the connection to the through-hull. When I cut through there was a 2" x 4" oval area that was heavily worn away, with the area ~1/2" around the hole being <1 mm thick (hose starts out ~ 5 mm thick). Although I didn't perform a full inspection of the entire length, there did not seem to be any other areas degraded so badly. Still...

The bad news: For the Mk 2 the hose is 2 INCH ID, and you only need 12 FEET. I think the dimensions Stu quoted (1 5/8" ID X 17 ft) earlier must be for the Mk I. Fortunately there was a marine supply store nearby that had exactly what I needed so avoided having to slice up the 18 foot section I had ordered. Even better, the original supplier I used will take the overlong section back for a full refund.

Pre-work hints:

1. Remove the wheel to make access to the aft locker easier.

2. Pull EVERYTHING out of the aft locker and aft cabin (or at least both mattress sections). It's pretty cramped in there, and you'll want every free cubic inch for maneuvering.

3. Strongly recommend that you take out the aft panel in the rear cabin to really get a good look at the hose routing. This also makes putting the new hose back in place much easier as there is the blower hose and several cable bundles running in that area as well. Doing it blind is a non-starter. NOTE: The steering gear cover is attached to the bulkhead and the overhead so that needs to come off as well to make this happen.

4. Leave the starboard laminated board in place. The center and port panels that support the mattress need to come off to access the muffler and hose.

5. Get FOUR new 316 Stainless hose clamps or something equally as good. IMHO the factory ones were not top of the line. Costs a little more, but you really don't want these corroding away on you.

Getting it done:

1. I found the drain on the muffler box was somewhat corroded and stuck. When I tried to open it and empty the box before commencing work, the entire drain came out. I was able to work it loose, clean it up, apply some teflon lube to the threads, and the reinstall it easily (don't forget the teflon tape). Don't over-tighten or you'll strip out the threads on the box.

2. Start the actual hose removal in the aft locker by removing the two straps holding the hose in place: one just behind the line for the port cockpit drain and the other at the top of the compartment (the fit is so snug that only the first one is really needed later). Take the drain hose off and unscrew the barb to make access to this strap easier. Just don't forget to put it back unless you want a following sea or the water in the cockpit to enter the tube and wash out the locker. NOTE: It is physically possible to get all the way into the locker (provided you are no taller than 5' 9" and 190#) to do some of this, but mostly it's a lot of awkward bending, reaching, and pulling.

3. Go to the aft cabin. The muffler is located on the port side storage area under the "L" of the center floor panel. The hose runs aft from there under the 2' x 3' panel. There is a vinyl covered metal strap holding the hose in here that needs to come off (I opted to not reinstall as it is a B**** to get back - try to insert a screw in a small space, in the blind and upside down using a stubby screwdriver). The hose runs from there under the tray for the aft water tank and then angles to port and up.

4. Getting the very stiff hose off the muffler box outlet is akin to trying to drag a very large snake out of a tight hole and will provide a nice opportunity to exercise your muscles and nautical terminology. Once you get it off pull it about 6" back into the cabin. This will pull the hump down from the top of the locker and make getting it out later far easier.

5. Now go back up to the locker, remove the through-hull clamps and pull the hose off. Muscle the hose out into the open and start pulling until it comes out. This may require some creative persuasion with your feet and hands to pull it roughly parallel to the hull and out from under the water tank tray.

6. When reinstalling I found it easier if I fed the new hose from inside the aft cabin. That way you can make sure it gets to the right place and does not foul on any of the cables or blower hose. Coming in from the aft locker is pretty tough due to poor visibility of the pathway and no room to work.

Total time on job (not counting getting the shorter hose): ~ 2 hours. I could probably have gone faster, but preferred to go slow as this was my first time trying this. Keep that ben-gay handy for afterwards.

Still sorting photos and will try to post soon. If you want them sooner contact me via email.

[dgill]

Hey Jeff,  Thank you for such a comprehensive explanation.  This will be very helpful as I prepare to tackle the same task soon.

[tonywright]

Excellent post Jeff. Many thanks for all the useful information.

I hope that I won't have to do this anytime soon, but I am left wondering what could have caused the problem. Do you have any theories as to the cause?  Did the engine run with reduced water flow or overheated at any time?

Tony

[Ron Hill]

Guys, Susan and D. Gill : NOTE:

MK I with a M25/25XP/35A engines have a 1 5/8" inside dia. exhaust hose about 17 feet long
MK II with an M35BC engine has a 2 " inside dia. about 12 feet long

The two models have their mufflers in differant locations and I guess Jerry Douglas decided that the M35BC engine needed less back pressure.  Also the location/routing of that exhaust hose is in differant locations in the two models.  A few thoughts