exhaust to hump hose

[horsemel]

I just installed the new hump hose last week and have a question that has been eating at me.  The exhaust pipe that comes out of the manifold and goes through the wall under the head sink to the hump hose (the one wrapped in white stuff) pivoted at the back of the engine.  It is supposed to do this isn't it?
Mark Mueller

[Ron Hill]

Mark : The exhaust riser comes out of the rear of the engine.  It goes straight back for some inches.  Then it makes a turn toward port between a bulkhead and the cockpit mold (NOT thur a wall!) .  Then it turns downward over the muffler.  The raw water from the HX enters near the end of the riser just over the muffler.  The hump hose attaches the end of the riser to the inlet of the muffler. 
Most of the riser has a metallic (Aluminum) covering over the insulation covering the riser.

I don't know what you mean by "pivot" ??  If you mean move? the answer is that the riser should be securely bolted to the engine and not move.  Maybe your engine mounts are so soft that the entire engine moves??  A few thoughts

[prh77]

M
ine does the same thing. I think the pipe threads where it threads into the fitting at the end of the exhaust manifold/coolant reservoir have worn.

[Ron Hill]

Mark & Payton : I'll guess that if the threads on the riser into the flange are "loose/worn" you'll could also be getting some exhaust fumes into the engine compartment.  The evidence of black soot should be evident in that area.

I suggest that you have someone shake the riser at the muffler and YOU see what is happening at the riser/to/flange connection.  Then make a determination.   

A thought

[Terry Forshier]

I just replaced my exhaust riser. The riser, where it screws into the flange may be somewhat lose making the riser able to pivot  (up and down) on the threads as they are not tightly screwed in. In order for the bolts to line up on the mount. I used some of the exhaust sealant hoping this would help the seal. Anyhow if this is what you are refering to i also had it. Mine appears fine.

[horsemel]

What Terry and Payton describe is what I have going on.  when I took out the old hose to replace with the hump hose, the whole thing dropped down to the muffler.  I just figured it was designed that way.  Just got back from the boat, so will have to look into it further next weekend.
Mark Mueller

[Ron Hill]

Guys : You can try to tighten the 3 nuts that hold the flange on to the engine.
 
If they can be tightened, you are very lucky that the loose flange didn't let coolant blow out of the coolant reservoir - when it's heated and under pressure!!

[Stu Jackson]

Guys : You can try to tighten the 3 nuts that hold the flange on to the engine.
 
If they can be tightened, you are very lucky that the loose flange didn't let coolant blow out of the coolant reservoir - when it's heated and under pressure!!

No, Ron, I don't think that is the issue.  Because the riser screws into the flange, the "C34 Instructions" from way old tech notes say to screw the riser in so the studs line up at the samew time you've "positioned" the riser at the back of the engine AND at the same time (!!!) under the head above the muffler at the top of the hump hose.  There inherently HAS to be a pivot, and I asked this same question a few years ago.  My answer to this condition was:  first, I noticed it because I had obvious "blowby", and second was that it did pivot!, and finally that muffler patch paste, originally suggest by Ron himself, I think, solved the problem.  His instructions were: "set it up but don't back off the position!"  Good advice.  But realistically almost impossible to do.    Do a search on blowby or blow by or blow-by, and read my post(s).

My next step will be to slather more muffler patch paste right on the already installed rsier connection to the manifold, kinda like a big glob joint sealant on the outside.  The patch paste should help with the threads inside the flange, but of there's ANY leakage, past the threads, the only place I can think of that gases can come out is where the threads come out of the flange.

Guys, it' just gotta move, if even from the resiliency in the hump hose connected to the flange open the MOVING bouncing engine.  It's a "moment arm" - finally, something else that we learned in high school and thought we'd never ever use!!!  Like triangles and boat navigation...

[Ron Hill]

For All :  Here are the instructions that I wrote up over 12 + years ago and professed in many posts:
 
Take the flange and put it in a vice orientated just like it will go on the engine (single hole to the bottom).  Then screw on the new riser ON and count the turns until the riser is aligned properly & tight!!  Make sure the riser is in the flange all the way ! Check and there should be NO wiggle top/bottom or sideways!
Unscrew the riser off and anoint the riser threads with muffler paste.  Then screw in the riser back into the flange the same number of turns always tightening and do not back up!
If you have to back up then start over again with some new paste.

There should be NO movement between the flange and the riser !!!  That's why it important to have the hump hose to the muffler and a nylon reinforced hose from the anti syphon valve to the riser's raw water inlet nipple.  You need that flexability, because the engine WILL vibrate!     

That's what I said! 

[Stu Jackson]

Good, you're right.  What Mark and I are trying to say is that it simply doesn't work in the physical world.  How do you get the riser onto the hump hose and the hump hose onto the muffler without moving the blinkin' riser up and down under the head?  

Then screw on the new riser ON and count the turns until the riser is aligned properly & tight!!  Make sure the riser is in the flange all the way ! Check and there should be NO wiggle top/bottom or sideways!

If it's tight it means it's bottomed out.  That means it MAY not be lined up at the other end.

That's all.

[horsemel]

Thanks for the photos.  It is a big help.  I think mine is probably too loose, but I will be checking it this weekend.  This is our fifth year with the boat and I suspect this situation has been going on since we bought her.  Isn't ignorance bliss?  Probably not.
Mark Mueller

[Ron Hill]

Guys : As I recall there are tapered threads inside the flange and on the riser, so the riser will not "botton out" per say!  If it does stop turning, the riser will probably NOT be oriented properly!  Hence the need for muffler paste.

That's why you have to put the flange in a vice and turn the riser until it's tight - noting the # of turns to get the correct orientation of the riser.  Then use the muffler paste getting the correct riser orientation and then install the mated pair on the engine. Installation on the engine is a two person job until the flange is mated with the bolts on the exhaust manifold.  
(Don't forget the gasket or remember to drain the coolant before taking the flange off! )

I'd get VERY excited, if I found something loose in the exhaust connections on any engine - CO leakage!   
A few thoughts