Another question....mixing elbow exhaust hose

[kito]

I am replacing my vertical manifold, nipple and mixing elbow on my ysm12. The exhaust hose is toast so need to replace. It had a 2" hump hose off the mixing elbow connected to the standard 1-1/2" wet exhaust hose going to the muffler. Question is, can I just go with 2" exhaust hose directly on the mixing elbow or should I go with a new 2" high temp hump hose again?. I don't like the idea of choking it down to 1-1/2" so close to the mixing valve. I am not sure how hot the mixing valve gets.....the 2" marine wet exhaust hose (Shields) may be fine.

 

[Ralph Johnstone]

. I am not sure how hot the mixing valve gets.....the 2" marine wet exhaust hose (Shields) may be fine.

Not familiar with your YSM12, but on my 2GM20F, the discharge is cool, somewhere in the area of 80-90 deg. F. I'm sure the Shields wet exhaust hose is fine even for those occassional incidents when the cooling water is briefly cut off ie. weeds or the thru hull is left closed.

I recently replaced my wet exhaust hose (Green Line) only because the end which slides on to the mixing elbow was showing wear because of all the times it had been pulled off for inspection of the elbow. The inside of the 12 year old hose looked to be in good shape.

 

[kito]

Thanks Ralph. Didn't realize it was that cool at discharge. I will go with 2" hose to the elbow then and forget about the high temp silicone hump hose.

 

[Ralph Johnstone]

the high temp silicone hump hose.

Kito,

Not familiar with the above hose. Can you explain what it is ?

I always thought the normal configuration was to run wet exhaust hose from the elbow to the muffler. Yours sounds a little different and now you've got me wondering if I'm missing something here.

 

[kito]

Ralph, I believe the PO used this hose since the muffler inlet is 1-1/2"......not sure he put in the correct muffler. He ran 1-1/2" ID hose that was 2" OD that fit into the ID of the hump hose off the elbow and hose clamped them together. A hump hose is just a short piece of hose with a larger "hump" in the middle. Usually used in cars to hook hard tubes together in high temp applications....like turbo charge lines. I guess the hump is for easier alignment. Not sure if it was even suitable in my application anyway.

 

[petersea]

hump hose is also designed to be a isolator in that it dampens vibrations from one attachment to the other as it will flex and lessen vibration/movement between the two mounts. Good application as with a engine that moves/vibrates and a stationary mounted muffler. I suspect the PO installed to lessen vibrations and you were asking about in other post on engine mounts.

[FONT=arial, helvetica]A hump hose has a bulge in it that is designed to allow the joint to flex. Extremely helpful for joints that tend to pull off, or anywhere that needs some freedom of movement.
(photo courtesy of Mach V Motorsports web site)
[/FONT]

 

[Chris Patterson]

Bid trucks use these commonly, to drive a million miles back and forth through the desert. Silicon hose is unmatched in their resiliency. Love the stuff. They love it too, it ain't cheap..

 

[Ralph Johnstone]

Ralph, I believe the PO used this hose since the muffler inlet is 1-1/2"......not sure he put in the correct muffler. He ran 1-1/2" ID hose that was 2" OD that fit into the ID of the hump hose off the elbow and hose clamped them together.

The most important thing here is that the system is 100% guaranteed sealed to avoid the discharge of CO into a confined space - your cabin.

I don't follow the need for the flexibility of this "hump fitting" as you're running a flexible wet exhaust hose from a vibrating engine to a solidly fixed muffler. Guess I'd have to see it to understand.

I think as a general rule, all PO's should be shot. The stories you hear around here are enough to keep you awake nights.

 

[kito]

The most important thing here is that the system is 100% guaranteed sealed to avoid the discharge of CO into a confined space - your cabin.

I don't follow the need for the flexibility of this "hump fitting" as you're running a flexible wet exhaust hose from a vibrating engine to a solidly fixed muffler. Guess I'd have to see it to understand.

I think as a general rule, all PO's should be shot. The stories you hear around here are enough to keep you awake nights.

Actually the muffler is not fixed. It sits on the floor under the battery shelf.....hard to get to. It stays pretty much in place when affixed to semi-rigid wet hose on both ends. It's got me thinking again though. Since the muffler inlet is 1-1/2" and the mixing elbow is 2" I will have to reduce somewhere anyway. Maybe the 2" hump hose off the elbow is the ticket since 1-1/2" wet hose is 2" od. Just don't know if the high temp silicone is good for salt water.

 

[Chris Patterson]

Salt water won't hurt it. Little will. Heat, oil, whatever. Silicone is the semi elite of hose.

 

[Ralph Johnstone]

Since the muffler inlet is 1-1/2" and the mixing elbow is 2" I will have to reduce somewhere anyway. Maybe the 2" hump hose off the elbow is the ticket since 1-1/2" wet hose is 2" od.

I'm probably reading this wrong, but it sounds like you want to jam the 1-1/2" hose (2" OD) inside the 2" hose (2" ID) and then clamp them together. Not a good idea if this is the intent. You always want the hose on the outside and clamped to a hard piece on the inside.

A 2" X 1-1/2" reducer coupling from the Hunterowner's Store here would be the safe way to go.

 

[Jalepeno]

My YSM12 manual calls for a 40mm exhaust hose from the exhaust mixing elbow (also called the goose neck in the parts list) to the water lift muffler and from the water lift muffler to the transom through hull exhaust fitting.
My records show that the local Yanmar authorised service shop used 1 5/8” (40mm) Trident T-Flex # 250-1580 when they replace the hose back in 2007.

 

[kito]

I'm probably reading this wrong, but it sounds like you want to jam the 1-1/2" hose (2" OD) inside the 2" hose (2" ID) and then clamp them together. Not a good idea if this is the intent. You always want the hose on the outside and clamped to a hard piece on the inside.

A 2" X 1-1/2" reducer coupling from the Hunterowner's Store here would be the safe way to go.

Ralph....would you stop making sense and confusing me I thought of that too and didn't like the idea of clamping to a semi-rigid hose. I am taking your advise and going with a 2" hump hose and 2" wet hose. I found a straight 2" fiberglass coupler. A lot cheaper than the reducing version. Just need a reducer for the 1-1/2" muffler now. May just find a short piece of 1-1/2" wet hose with 2" od and stick it on the muffler nipple and clamp it.

 

[Jumpstart]

Ran into similar problem when I replaced my Waterlift muffler. Ended up getting a reducing silicone coupler from Pegasus Racing (automotive in Wisc) and an aluminum splicing nipple from them. Works great and not too expensive. PO used the smaller hose od within bigger hose ID trick. Not a good idea. https://www.pegasusautoracing.com/

 

[mitiempo]

The best solution is to match the waterlift input size with the exhaust manifold size do you don't need adaptors. Why mis-match it?

 

[kito]

The best solution is to match the waterlift input size with the exhaust manifold size do you don't need adaptors. Why mis-match it?

The PO installed a muffler with 1-1/2" nipple that's why I need to reduce. I have on order a 2" silicone hump hose, 2" fiberglass coupler and 4 feet of 2" wet hose. I will install a short piece of 1-1/2" with 2" od wet hose on the muffler nipple. I will double clamp it. Should work fine.

 

[Ralph Johnstone]

I will install a short piece of 1-1/2" with 2" od wet hose on the muffler nipple. I will double clamp it. Should work fine.

I glossed over this part in your recent post. The inch or so of 1-1/2" hose is used as a bushing between the inside of the 2" hose and the outside of the 1-1/2" mufler connection.

Like I said, you've got to be there to see it.

 

[kito]

I glossed over this part in your recent post. The inch or so of 1-1/2" hose is used as a bushing between the inside of the 2" hose and the outside of the 1-1/2" mufler connection.

Like I said, you've got to be there to see it.

Do you see a problem with doing that?. It will be double clamped onto the mufflers SS nipple. I would rather do that than deal with adding a reducer at the muffler inlet. The more reducing pieces etc. add more hose clamps and more potential leak paths.

 

[Ralph Johnstone]

Looks Good to Me ...................

It will be double clamped onto the mufflers SS nipple. I

..................... I'm just ticked that I didn't think of using the 1-1/2" hose as a bushing sooner..

The hose material is quite firm and the two clamps will make a 110% gas tight seal. The caveat here is to make sure that both gear clamps are indeed seated over solid muffler nipple.

 

[mitiempo]

I have always understood that if an engine has a 2" exhaust inlet it shouldn't be reduced but should remain 2" throughout. That is why waterlifts are available in all sizes.

The previous owner used the incorrect size. It has to evacuate the exhaust as well as the cooling water that the engine's cooling pump passes through the system. I certainly wouldn't want to restrict it.