Hump Hose & Exhaust Hose Couplings

[Roc]

I will pull my muffler off to fix a leak, and planning on re-installing it with a hump hose.  I received the new hump hose from Catalina, part #80648, and noticed it is very rigid.  I have a MkII, so the elbow coming off the engine points downward, and the input to the muffler is on the side (not the top like the older ones).  As a result, the hose will need to make close to a 90 degree bend, and in looking at the hose, I don't think that can happen without it kinking.

Anyone with information on the installation of a new Hump Hose on a MkII (w/M35B engine)would be greatly appreciated.

Thanks,
Roc-

[kss1220]

I installed one last year.  I had to shorten it just a bit then soaked it in boiling water.  Put on some gloves upon removal from the water.  Then I liberally put dish soap on the inside of the hose as well as the riser and muffler nipples.  Installed the muffler end first as far as you can make it go.  Then fold the top of the hump hose over to clear the riser and then push and twist like crazy.

[Roc]

Kelly,
Based on your hull number, you have a MkI, which from what I believe has the ports located on top of the muffler.  This allows a straight shot of the hump hose from the vertical inlet of the muffler to the elbow on the engine.  My muffler inlet/outlet ports come out on both ends, horizontally.  I left a message to Kent Nelson at Catalina and he responded, saying that the hump hose won't work on a C34 (MkII).  I'm going down to the boat this weekend and will lay the hump hose next to the current hook up to see if it will be able to make the turn.  If not I will try to use the existing hose when I re-install the muffler after I repair the crack.

Roc-

[John Langford]

I would like to revive this older discussion of installing a hump hose on a Mk II M35B diesel.

Roc, were you able to fit the 15" hump hose successfully?

If not, I see that Catalina Direct sells 6" and 8" silicone hump hoses. Can anyone see any problem with cutting the last 6 " out of the relatively straight section of the existing black wire reinforced hard rubber hose and inserting the 6" hump hose between the remains of the old hose and the water lift muffler using a 1 5/8" OD hose coupling with smooth outside walls (assuming one could find such a coupling)?

And does anyone know why the outlet from the muffler is 2" while the inlet is 1 5/8"?

[Stu Jackson]

John,

I see no reason you couldn't do that.  There are couplers made.  I purchased one for our exhaust hose from the muffler to the stern a few years ago.  The piece of hose at the muffler was getting wonky, so I cut the first few feet off and bought a 45 degree coupler.  I believe it was made by Vetus Products, the same guys who make the engine mounts and aftermarket mufflers.  I just checked their website, but their catalog is neanderthal website 101 and impossible to read.  I'm sure I have the model # and part on my own computer upstairs and should be able to get up there sometime soon and will post it.  They come in straight, 45 and 90 degree couplings for high temperature applications in various sizes. 

I would put the hump hose on the muffler end and leave the old black hose on the exhaust riser.

[Ron Hill]

Roc :  I have pictures of the MKII exhaust system (on a new C34) and I see your quandary !  The pictures that I have also shows a standard wire reinforced black hose connection between the exhaust riser and the inlet to the muffler.  
This seems funny as I first heard of a hump hose from Jerry Douglas himself back about 1999/2000.  He stated they were putting this "new hump hose" on the C34s/C36s to dampen the vibration on the inlet muffler connection !! In fact he sent me a new muffler for a MKII that I had to send back because the openings were of the sides and NOT the top.  I'll guess that it didn't work out or for some other reason so they stopped putting the hump hose on the M35BC engines in the C34s !  Maybe Gerry got his boats mixed up and meant only on the c36s?
All I can say is to make sure that the hump hose is - 1. Long enough and 2. That the hump won't rub on the cut out of the bulkhead.  If the hump hose is long enough and will not rub on anything, I'd use the hot water (or carefully with a heat gun) to soften it and install it on the engine and muffler.  

John : And does anyone know why the outlet from the muffler is 2" while the inlet is 1 5/8"]?  I'm sure it 's reduced in diameter for the needed engine back pressure, as the outlet from the Westerbeke exhaust manifold is 2 inches !!!

A few thoughts.

[John Langford]

Thanks Ron. Then I am assuming that the engine wouldn't mind if the muffler outlet was 1 5/8". This would allow the use of more after market mufflers like those produced by Vetus. All of them have the same inlet and outlet size. Catalina is the only muffler maker I have ever seen that has 1 5/8" going in and then 2" coming out. I have never been able to sort out why it need be that way.

[Stu Jackson]

Hose Coupling

John, his is the model # of the hose coupling I bought in Sept. 2005, from my inventory: 

MMC EL-158-0045 45 deg. 1 5/8" fiberglass

I'll do some more digging but I believe it is a Vetus product.  Perhpas if you check their website you may be able to search with this model #.

[Ron Hill]

Guys, Susan & D. Gill : Catalina is the only manufacturer that I know of that uses a 1 5/8" wet exhaust hose diameter.  I say that, but there must be others as the black wire reinforced hose (wet exhaust rated) must be used by someone else beside the sanitary head people !?! 
I do know that Catalina are the only people that use a 1 5/8" wet exhaust "silicone" hump hose. 
Don't know why you would worry, but Good Hunting anyway. 

You might want to read the upcoming Mainsheet on why a C34 MK I should not even consider using other than a Catalina muffler.  A thought 

[Roc]

I did not put the hump hose on my MkII, as stated earlier, it doesn't seem to work. What I did use was a Vetus exhaust hose.  It is advertised as being very flexible because of the ribbing.  It makes the 90 degree bend very easily.

[John Langford]

Hi Roc
Sorry to be reviving yet again this old thread but I have just had my stainless steel exhaust riser rebuilt (leak at one of the welds) and I want to replace the original, very hard wire reinforced hose which connects it to the muffler.  Do you recall if the Vetus exhaust hose you used was the 40mm size? The OD of the riser and muffler pipes is 1 5/8" (1.625") so the 40mm Vetus hose would be a bit small (1.57"). If you used the 40mm did you have any trouble getting it on?

More generally, does anyone have any idea whether the Vetus hose is appreciably more flexible than the more widely available Trident flexible exhaust hose which comes in a 1 5/8" ID size?

[Ron Hill]

John : I can't answer all of your questions, but the blue Trident hump hose is very nimble.
 
More nimble than the ribbed Vetus hose? - not sure anyone on this net can answer that !! 
A ribbed hose that doesn't have wire reinforcing (for acute turns) should be OK. 

[Roc]

Hi John,
When I read this, I remembered I answered your question in a previous thread...here it is....

http://c34.org/bbs/index.php/topic,6279.0.html

[cmainprize]

Hi Roc
I replaced the hose from the riser to the muffler this year with 1 5/8 silicone hose.  It is very soft and kinked when I tried to make the sharp bend.  I added a 45 degree elbow that I made myself because no one had one in stock and I did not want to wait.  It was simple and works well.  pics attached.

Cory

[cmainprize]

This is a close up of the coupling I made.  10 layers of glass and epoxy.  Simple.

Cory