Hump Hose Replacement Experience and a Vented Loop Connectio

[Stu Jackson]

Another project off the list, and another one added to it!

First a little story, and then a question.

Yesterday, I replaced my old exhaust hose, due to a leak at the bottom of my old 1986 exhaust hose at the Aqua-lift muffler.  I’m keeping my fingers crossed that this is the LAST source of our bilge water, having installed dripless packing, replaced the leaking head outlet valve, trimmed and reseated the aft end of the exhaust hose at the transom thru-hull, and checked all the other sources noted recently in this Message Board.  

Ken Kay reported this same leak-at-the-muffler problem in July 2000, and the old Mailing List had a number of helpful replies from Ron Hill.  If anyone is interested, I can either email them or post them here - please let me know.  

I purchased my new 8 inch long, 1 5/8 inch diameter blue silicone rubber hump hose direct from Catalina a few months ago, and Catalina now has them in stock available for our older boats.  It is my understanding from the old Mailing List correspondence that newer boats may use shorter 5 inch hump hoses.  

My two main concerns had been the condition of both the fiberglass inlet tube at the top of the muffler, and the raw water nipple at the riser.  About 3 inches before the riser ends there is a small nipple that is welded into the riser.  The small 5/8 inch outlet raw water hose from the heat exchanger connects to this nipple and mixes water that cools the exhaust gases before they enter the muffler.  Our leak at the 1 5/8 inch muffler entry could have been from the big old exhaust hose itself or from the fiberglass tube.  The welded connection is notorious as a weak point.  Fortunately, both were in good shape.

As I was removing the old exhaust hose, I found that the main exhaust riser which goes back to the engine manifold has a vertical movement at its end underneath the head sink.  This seemed to make sense to me, since the length of the exhaust manifold pipe and the inlet at the muffler are about two inches or more long each.  The new 8 inch hose needs the extra space, when the main riser is raised as high as it will go, between the bottom of the pipe and the two inch high top of the tube on the muffler to allow you to slip the new hose into the space, up two or three inches onto the riser, adjust it to slip over the muffler intake, and then push down to seat it on the muffler tube.   I did have to rotate the hose clamp at the end of the insulation on the pipe to get the screw of the clamp off to the side to maximize the height of the lift of the riser pipe.  That little bit of extra height gave me room to slide the new hose in, onto the riser and over and down onto the inlet tube.

I sure hope that the exhaust riser is supposed to move!  It seems well seated at the engine connection end.  The good news is that the new hump hose is installed and double clamped, although I did have to trim about 3/8 inch off one end to be able to get it up and over the muffler inlet tube once it was snugged up on the main riser.  

Ron Hill suggests: "don't o ver   tighten the clamps.  I used acid resistant hose clamps which have rolled edges so they are smooth and will not cut into the hose.  I ultimately  used a piece of leather between the hose and the clamp to doubly ensure that the clamp would not cut in to the soft single hump hose."

While I was at it, I wanted to replace the short  5/8 inch raw water hose.  This is the shorter section of the long raw water hose that goes from the heat exchanger to the nipple, the short one that connects from the aft end of the vented loop to the nipple.  I unscrewed the vented loop from the wall under the head sink, left the long water hose from the heat exchanger connected to the vented loop, and removed the old short 5/8 inch hose from both the vented loop and the nipple. Both ends came off easily.  

The metal nipple connection to the main riser looks fine, but the hose was seriously deteriorated, and the upper hose clamp band was cracked in the back (not visible) and was ready to let go at any time.  I suggest that you check all your hose clamps regularly, especially those that are “out of sight, out of mind,” and for sure those that are in hot environments.  Even if the hoses are OK, the clamps could be questionable.

Figuring that replacing this short hose would be an easy task and let me startup the engine to check it all out, I tried to get the new 5/8 inch water hose onto the vented loop with no success at all.  I checked the writing on the old hose, and sure enough it was 5/8 inches, same material.  In order to try to get the mouth of the new hose open a bit more, I inserted a tapered wooden plug into the end and pounded the plug in with a mallet.  I even soaked the wooden plug, hoping it would swell once inside the hose.  I took off the vented loop, and did this work in the cabin, not under the head sink.  After a few hours of no go, I brought both the hose and the vented loop home to see if I could get the hose onto the loop when I had more time.

Question is: Any ideas about how to get the new correctly sized, 5/8 inch new wire reinforced hose end onto the vented loop?

[SteveLyle]

Petroleum jelly, something like that?

[SteveLyle]

Got a heat gun this year for stripping varnish - it's come in handy for a bunch of other tasks as well.

If lubrication and heat don't work, you need a bigger hose (or smaller nipple).

[Stu Jackson]

Yes, I've tried those, no go.  When I inspected the inside of the old hose, it appeared that it had been "routed" out a little bit.  I'm not keen on reducing the hose wall thickness, but it may not be bad since it's up around the barb on the vented loop, and will have the hose clamp around it right there.  I could do that routing with a Dremel tool.  I could also shave a bit off the barb.  Any cautions there?  The hose fits perfectly on the nipple end, no problem there.

[Stu Jackson]

Ron, you say: "The bad news is that the engine shouldn't move that easily. You might want to check your mounts as there should be NO flexibility in the riser."

The engine isn't moving, the whole riser pipe "rotates!"  It's like a big moment arm.  It swings inside the back of the big bolted-on fitting that holds it to the back of the engine manifold itself.  Since I have the old original engine mounts, you just know "it ain't goin' nowhere."

If the riser "arm" doesn't move, how would one get a new hose installed?  My new "flexible" (haha) hump hose didn't bend very much, and certainly not enough to get it on the fittings if the riser arm didn't go "up," without having to cut too much of the ends off and make it too short.

Gee, does this mean I get to get a new riser?

Anyway, how about your ideas on the hose "routing out" or scraping down the loop?  I understand your ideas about lubricants, and will also try that.  Only reason I ask is that it's the first time I've ever had this problem.

[alwsail]

Stu
I have had luck dipping the hose end in boiling water. Makes it softer and fits right over after that. Use soap as a lube.
Capt Al.......still here!

[Roc]

Hope all has been well....So, what's been the plan since you sold Kindred Spirit??  Bigger boat?? (Catalina I hope) :)

Roc-

[Stu Jackson]

Here’s a followup to my post and your replies:

Connection to Vented Loop:  I was eventually able to get the 5/8 inch hose onto the vented loop thanks to using boiling water at home.  Thanks to Al.  Doing a bit of research in marine catalogs, I think I’ve determined that the vented loops come in ¾ inch and larger.  Gee…wonder why we had some difficulty getting the 5/8 inch hose on the ¾ inch barb?!?!  Thanks, Ron.

Connection to Muffler:  I was wrong about the connection “looking fine.”  It wasn’t.  When I started up yesterday, the leak continued.  I disassembled the hoses (again), and more carefully inspected the base of the fitting for the hose at the top of the muffler.  There appeared to be some small cracks and glazing.  Instead of immediately ordering a new muffler, I went into my files and the Search Engine on the website, and also found Ron’s descriptions of his muffler replacement.  Great information.

Before I started to replace the entire muffler, I figured it might be possible to rebuild the base of the hose connection.  I remembered an earlier discussion and used the website Search Engine “muffler replacement,” (search for EXACT phrase) and found Larry Lemieux’s post in FAQs.  Larry had rebuilt his unit.  Larry said: “I also had cracks and leaks in my 1987 muffler, around the input and output tubes. I looked around for a replacement, but could not find anything that would fit in the height available. Before ordering a new one from Catalina, I decided to try to repair it and completely broke the input tube out trying to remove the hose. I used some West epoxy, which I thickened and applied with filleting, to repair the tubes.  The repair was done about a year ago and has held up just fine, so far. I'm starting to trust it, but still check it at least once each time out, because there is a fair amount of vibration from the hose, which I think probably contributed to the original problem.  It was probably the least expensive repair to date, about $20. We also had the same problem on our C30, but I never fixed it. Learned a lot since then.”  This was obviously before the new hump hoses became available.

Thanks to Webmaster David Smith for the great useful search engines.

Given Larry's impetus, I tried the same approach yesterday.  Since the cracks seemed to be minor and at the base of the fitting, but still producing a definite leak, I used MarineTex to fill in a large bead around the base of the fitting into the muffler, which I carefully feathered up the shaft to assure that the hose would still fit.  

I left the Marine Tex to sit and cure overnight, and reassembled the hoses this afternoon after sanding the surface smooth.  Since Marine Tex dries harder the thicker it is, I was comfortable trying it out.

It works just fine!  Took her out for a spin to cruising temperatures and rpm, and this problem is solved.

Now all I have to think about is replacing the exhaust riser piping because of its twist, but we’ve solved the short term issue.

Thanks again to all of you for your assistance.  And for those of you with questions, I recommend trying the great Search Engines, the two separate ones  on the website and the Message Board.  In many cases, “the answer is out there.”

Stu

[Stu Jackson]

Late Followup:

When I replaced the exhaust riser last month, I "discovered" that there is, indeed, a 5/8 inch antispihon fitting.

Much easier to get the hoses on to the right szed fitting!!!

Stu

PS

We also installed a new 3 inch heat exchanger.

[isabel 0098]

Ok guys ready for the definitive exhaust solution; Old riser removed from the manifold, new flange ordered from westerbeke about 60.00 with new studs and bolts. New riser built from galvanized pipe 30.00 from hardware store/plumbing supply. Hump hose from catalina direct w/clamps. Small repair made to strengthen inlet and outlet on the muffler with epoxy resin ( very solid). Put the riser together and check fit. after adjustment, mark the pipe and disassemble. Seal thread and reassemble. Proper installation leaves about 2 inches clearance from pipe to bulkhead on all sides. Wrap pipe with insulating tape, ( I'm only concerned here with protection from fire, so I didn't overdo it, I dont mind a little extra heat.) Don't wrap until after runup and a little use to check for leaks. Exhaust system is now bullet proof for at least 5 years. The job is not really hard just awkward B. Dell Isabel 0098