Hump Hose Replacement - How I did it - with pictures

[Dave Spencer]

After some gentle nudging from the forum mid winter about my old style exhaust hump hose, I started the process of replacing it with the more forgiving silicone hose sold by Catalina Direct.  After measuring my current hose, I ordered the 8" hose and a few clamps from Catalina Direct.
http://www.catalinadirect.com/index.cfm?fuseaction=product.display&product_ID=1022&ParentCat=474

This weekend, I got it installed.  It took far less time than I thought (a first for boat maintenance).  It would have taken even less time had I not stopped to scratch my head and rethink if what I was doing was right.
My engine is an M35AC with a 1993 serial number.

After loosening the clamps, I started cutting away the old hose using the coaxial tool extension my rotary tool.  (Canadian tire version of a Dremel Tool)  Sparks will fly as shown in this picture but you are only cutting through the steel spiral reinforcement in the hose. Unless you have cut far too deeply, you are not cutting the manifold.
-1st picture

As you cut the steel spiral reinforcement, the hose will pop open.  There is about 2 1/4" of engagement length of hose on the exhaust manifold and another 2 1/4" on the muffler.  Once you have cut through the full engagement length, cut a little bit more to make it easier to pull the hose off the muffler.
-2nd picture
I could have cut the entire hose in half but I chose to pull the rest of the hose off the muffler using channel locks

The 3rd picture shows what I saw once the hose was completely removed.

The new hose was fractionally longer than the old one and I didn't like my chances wrestling it onto the muffler and manifold ports so I cut about 1/4" off each end and the fit looked perfect.
I slid the new hose onto the manifold and I was pleased that it fit snuggly but wasn't brutally tight.  I then forced the bottom of the hose up onto the muffler port on an angle.
-4th picture

After a bit of twisting and coaxing I got the hose all the way onto the muffler.  Tighten up four hose clamps and the job is done.
-Last Picture

The whole thing took less than an hour.  The key to the job was the Dremel tool with the cutter on the end of a coaxial extension.  It would have been far more difficult without it.

Good luck
 

[Dave Spencer]

Here is a picture of the old and new hose and the Canadian Tire version of a Dremel tool that I used.
The tape measure show the engagement of the hose onto the exhaust manifold.

[Indian Falls]

If you don't have a dremel tool, you can try what I did:

I slit the hose vertically with a razor knife then took side cutters and snipped about 6 of the wires from the top down and pulled them out right out of the hose with a vice grip locking pliers, after the 6 springs were removed, I filleted the hose along the fitting surface.  cut the hose in half cross-wise and pulled both pieces off their fittings.  Shoving the hump hose back in with a little dish soap was easy.  Only 1 hour of fooling around.

[Ron Hill]

Dave : Good job!! 

If you haven't done it already I'd recommend that you change out the stiff 5/8" wire reinforced hose from the anti syphon to the nipple on the exhaust riser- to a nylon reinforced hose. 
Less engine vibration is transmitted thru the nylon hose (vrs the wire reinforced hose) to the weld joint that holds the nipple into the stainless riser pipe.   A thought

[Dave Spencer]

Dan,
Yes, the knife and side cutter option would have worked.  I didn't know the construction of the hose so I likely would have fooled around longer than necessary trying to figure it out with the hand tools.  The Dremel tool is my new best friend on the boat.

I've learned so much form this forum I wanted to give something back by documenting what I did so others could do the job with confidence. 

Ron,
Thanks for the tip about the anti-siphon hose.  I'll get on that asap.

[Stu Jackson]

I use Rector's Pipe Dope when I install the hoses.  Allows pretty easy removal.  For smaller hoses I use Lanocote.

[Kevin Henderson]

WOW... Thank You Dave

I had ordered the 8" hump hose from Catalina Direct and followed your procedure using my dremel.  It was a little scary at first but I couldn't believe how easy and quickly the upgrade was accomplished.

Ron... While I was at it I also replaced the 5/8" hump hose with a nylon reinforced hose.
 
Anyone thinking of doing this project should not hesitate.  It is ridiculously easy to do and the results are very noticeable.  I started the engine and checked my work.  There is a distinct difference in the amount of vibration from the exhaust down to the muffler.  And... I think I may have even noticed a little quieter sound to the whole engine...

Awesome project with distinct results..  Thank You Dave! 

[Dave Spencer]

I'm glad it worked well for you Kevin.

Next Project - Replace my erratic old Autohelm with a shiny new Raymarine X5 and replace / re-rivet the conduit in my mast that has come loose.
http://c34.org/bbs/index.php/topic,7170.0.html
http://c34.org/bbs/index.php/topic,7164.0.html

Hopefully I'll be able to get to those jobs within the next 6 weeks or so - after peeling the winter cover off the boat.

[stevewitt1]

Dave:

I know you might not want to slow down on these things while you are "on a roll!"  So, let me offer my boat for you to continue honing your upgrade skills on.

Being serious for a moment (rare moment in my world) I have to state that C34.org presents so many valuable Critical Upgrades and great ideas from everyone here that a simple mind like mine seems to go in "idea overload" quickly.  I just have to prioritize things and move forward.

It just seems that every time I read a new thread I think; move that one up on the "to do" list.

Thanks everyone for all the great information.

Steve

visit us at www.ocontoyachtclub.com and www.warbirdsix.com

[efhughes3]

Why have I never thought of using a Dremel to cut old hoses off? So much easier than a knife, particularly when working in an awkward situation. Thanks for the idea!

[Ron Hill]

Guys : The Dremel tool works best for wire reinforced hose removal.
A heat gun works best for other hoses.  It softens the hose and lets you pull it off the connection.

A thought

[Ken Juul]

You can also get a handle that will allow you to use a hacksaw blade without having the loop to tension the blade.  Will post a picture when I get home.  It only works if the teeth are aligned to cut in the pull position.  Great for getting into tight places if you don't have a dremel.