Exhaust Problem

[Michael1974]

I havew an exhaust leak that appears to be coming from the aftmost spot under the cockpit on the starboard side. To access it requires removing the water heater and several hoses and looking(?) over a plyhood bulkhead. The exhaust hose fits over a pipe of some sort, that because of the abundant light can not bee seen to determine if the problem is the hose or the pipe. If the pipe is metal the exhause could have weakened the sides of it, if the pipe is plastic, fiber glass or PVC it could be cracked. I don't want to try to pull the hose off until I have an idea what I have.
It appears that the exhaust exits the same hole that the starboard scupper uses. Scupper appears to drain well so I don't believe there is a plug somewhere.
Has anyone else had this problem and found a simple fix? Also does anyone know the I.D. and length of the exhauset hose. If I have to cut the hose up I'll lose the original length.

Thanks

 

[redhead78]

Maybe u can hold a camera or a phone in there and try to see what u are up against first. I used my phone and stuck it in places behind engine compartment and took pics...then u may be able to plan a repair....careful don't drop phone.... Red

 

[s sauer]

H28.5 Exhaust

First, the scuppers have thin walled off-white spiral reinforced hoses that cross at the stern so the port scupper hose exits the hull on the starboard side and the starboard scupper hose exits on the port side. The exhaust is a much thicker reinforced black marine hose, probably about 2-1/4" diameter rising thru the sail locker from the warterlift muffler at the front of the starboard sail locker and dropping down as it goes aft past the water heater to connect to a built-in reinforced fiberglass tube exiting the hull a couple inches from the scupper 'tube'. All three tubes are of similar construction and exit the underside of the hull at the water line boot stripe. A similar heavy walled black reinforced marine exhaust hose comes off the aft end of the Yanmar 2GM20's exhaust elbow, and drops down and runs from the engine compartment into the side of the waterlift muffler at the forward end of the sail locker. Now if any of these hoses were leaking with the engine running, you'd likely be pumping hot water & exhaust into that sail locker at at least a gallon per minute at idle. What are you seeing that seems to be the leak? It may be possible to crack the fiberglas tube where it meets the hull or perhaps get some damage to an aging exhaust hose within the sail locker, but again with a wet exhaust system you'd be takin on alot of water and you didn't say that.

 

[Michael1974]

The muffler is not a water type. I don't see a way for water to enter the muffler. You're correct the black exhaust hose is about 2 to 3in I.D. There is no water coming in the boat but there is definitely exhaust, enough so the port berth has carbon black on the wall coming from the locker. That the pipe is fiberglass is helpful. The crack must be above the hull line since there no water entering. Now how to get the exhaust hose without destroying it or the fiber glass tube.
Thanks again.

 

[Michael1974]

Also, on the underside of the hull there are only two exiting ports below the waterline.

 

[Dan Hill]

O dear! Where to start? If you don't have a water type muffler you've found your root cause of the problem. Without water cooling your exhaust muffler/hose will melt some very important parts of your boat.

Do you have a thru-hull and valve by your stiffing box? That feeds your motor and exhaust cooling water.

The scupper drains have nothing to do with the exhaust port, unless someone did a very bad thing to your vessel.

Have your ever changed or inspected your impeller in the sea water pump? Do you have one?

You really need to do some research of and on your vessel and answer these questions.

Exhaust fumes in your starboard locker are a small part of your problems at this point IMHO.

 

[s sauer]

Michael,
The Hunter 28.5 started production in 1985 withYanmar 2GM20F engines. Thru the production period, I believe till 1988 they were all fresh water cooled engines; however the configuration of the Sail locker construction sometimes had built-in waterlift muffler and built-in fuel tanks at the bottom of the sail locker. I've owned ours since new in 1986 and it has a fiberglass waterlift muffler at the forward end of the sail locker and a Polyethelene fuel tank just aft taking up almost the entire bottom of the locker, with the hot water heater aft behind the fuel tank.
With the exhaust / soot you are describing it sounds like you may not be getting enough water into the exhaust system. Believe me please, if you have black rubber exhaust hoses it MUST be a wet exhaust. Look in the quarter berth for a seawater intake and strainer behind and to port of the transmission. When you open that seacock intake it provides water that runs thru the strainer then to the forward starboard side of the engine to the belt driven pump. A rubber impeller inside that pump pumps water up to the front of the jacket of the heat exchanger on the top starboard side of the engine. The water comes out the back of the heat exchanger into a 3/4 ID hose that goes to starboard to the sail locker bulkhead to an inverted U shaped air-gap, the return hose comes back into the engine compartment and connects to a nipple on the top of the 'U' shaped water injection elbow wher it is mixed into the exhaust coming from the back of the exhaust manifold right behind the heat exchanger. If no water is going into your exhaust system at this point you should not be running the engine as you will burn up the rubber exhaust hose and maybe the waterlift muffler. Your overheat alarm should sound off as the engine overheats.
It is possible that the water injection elbow is coked up or that the water lift muffler (built-in or separate canister) has been damaged by winter freeze-thaw if it wasn't properly winterized.
I'd strongly suggest you go on-line and order a Selock Yanmar engine manual as it will show you photos of all these systems and possibly help you with repairs.
Another resource is : wwwhuntertwentyeightfive.com I just posted a cometary a couple weeks ago on cleaning out the water injection exhaust elbow as a standard maintenance issue.

 

[Michael1974]

S. Sauer,

The valve for engine water inlet is fully open. Screen is clean. Impeller is fine. Engine is not overheating. Exhaust hose has cracks along its bend from age but is not leaking there. Even with water in the muffler canister that doesn't explain why exhaust gases remain in the boat, specifically at the aft wall. Assuming everything is intact, the exhaust gases have no other way out of the boat except through the exhaust hose and exhaust port, thus the idea that the hose or connecting pipe is broke or cracked. The entire boat is stock with no significant modifications and has performed very well. The muffler is stock and as you describe, but water inlets are not visible without removing the muffler etc. The water in the muffler quiets the combustion noise. The water doesn't carry the gases, but passes threw the exhaust hose with the exhaust. The scupper hoses do cross as suggested in an earlier post. However, there are only two ports in the hull bottom, and both appear to be clear of debris, therefore my guess that the exhaust must transition into the scupper hose, or the other way around. I've had this boat over ten years and know it well. This problem is a new one and I'm merely looking for way to access the leak without destroying things. Again, I am observing exhaust gases not water leakage.

 

[Michael1974]

Wrenchbender
There are a variety of mufflers on the market, both wet and dry. The exhaust hose is designed not to melt and is designed to withstand very high temperatures. I didn't identify the muffler as a water type because input water lines can not be seen. If the boat had no impeller it would quickly overheat and, barring a failed temp indicator, the heat alarm would go off. Besides I change my impeller every fall at haul out when I insect for wear and change the oil. As stated earlier, the engine water inlets are open and clear. My initial question involves the type of hose to hull connection and removal of the hose and the size of the exhaust hose.

 

[Michael1974]

S. Sauer,

Getting the manual is a good idea as mine is not a through one. I'm going to read your post on ho285. Thanks

 

[Dan Hill]

As S. Sauer pointed out all of our 28.5s have water lift mufflers of some type if you have any rubber hose involved. The water is injected AT the engine into the mixing elbow, not at the muffler. It's injected there to cool the entire exhaust system, including where it passes thru your hull, think about it! Get that manual.

As many have stated here..... Your boat, your wallet, your repair. Do it your way.

 

[s sauer]

Michael,
You might heck a couple things before trying to remove the heavy walled exhaust hose.
If you run the engine for a few minutes, does the exhaust at the stern give the usual spitting and gurgling sound, or has it become more hollow and truck like? You will have heard that hollow sounding exhaust if you ever forgot to open the seacock before starting the engine.
After idling for at least a few minutes to warm the engine and check the exhaust noise, shut off the engine and CAREFULLY reaching in from the front, see if the silver "U" shaped injection elbow at the back of the engine is hot to the touch and if the black exhaust hose comming out the bottom of the 'U' is also warm or hot.
Wiith a well functioning water injection system you can put your hand on the top portion of the "U" and the black exhaust hose without being uncomfortably hot to the touch; however if the water or exhaust side is getting partially blocked, that assembly will be much warmer, or even too hot to touch. You may see sooty exhaust on the water as well.
Also, standing in the cocklpit behind the wheel, open the removeable storage compartment under the aft starboard seat and remove the 'liner'. You should be able to look directly into the stern cavity behind the water heater and see the hose connection(s) at the inside of the hull. However, I have no idea of what kind of contortionist it would take to get in there and remove hose clamps and the exhaust hose. While working on the rudder bearings, I've tried to access that stern area from behind the water heater in the sail locker and almost got stuck in there myself. The port side is actually worse to access, but you can try to look in there by removing the overhead access panel in the quarter berth ceiling,which extends aft from under the steering pedestal.

 

[Dan Hill]

My curiosity will be my undoing someday, but I just gotta ask. IF you don't have a water cooled muffler BUT you do have cooling water coming into the engine compartment, how does the cooling water exit your vessel?

 

[s sauer]

Michael,
I just came back from my boat today and I opened up the starboard storage compartment, took out the liner and could easily see the exhaust pipe running behind the water heater, thru the plywood bulkhead and turning down onto the tube exiting the hull. Since I was motoring at the time that part of the underside of the bootstripe was underwater by a couple inches. At idle in the slip it was just at the waterline.
One of the scupper exit tubes was within a few inches, so you should be able to check out the area on your boat with a flashlight and see what's happening.

 

[Michael1974]

Michael,
You might heck a couple things before trying to remove the heavy walled exhaust hose.
If you run the engine for a few minutes, does the exhaust at the stern give the usual spitting and gurgling sound, or has it become more hollow and truck like? You will have heard that hollow sounding exhaust if you ever forgot to open the seacock before starting the engine.
After idling for at least a few minutes to warm the engine and check the exhaust noise, shut off the engine and CAREFULLY reaching in from the front, see if the silver "U" shaped injection elbow at the back of the engine is hot to the touch and if the black exhaust hose comming out the bottom of the 'U' is also warm or hot.
Wiith a well functioning water injection system you can put your hand on the top portion of the "U" and the black exhaust hose without being uncomfortably hot to the touch; however if the water or exhaust side is getting partially blocked, that assembly will be much warmer, or even too hot to touch. You may see sooty exhaust on the water as well.
Also, standing in the cocklpit behind the wheel, open the removeable storage compartment under the aft starboard seat and remove the 'liner'. You should be able to look directly into the stern cavity behind the water heater and see the hose connection(s) at the inside of the hull. However, I have no idea of what kind of contortionist it would take to get in there and remove hose clamps and the exhaust hose. While working on the rudder bearings, I've tried to access that stern area from behind the water heater in the sail locker and almost got stuck in there myself. The port side is actually worse to access, but you can try to look in there by removing the overhead access panel in the quarter berth ceiling,which extends aft from under the steering pedestal.

Stu,
This weekend I rechecked the water inlet valve and impeller and the associated hoses. Everything checked out. Nothing plugged. Did not find the exhaust elbow, I think it is further under the engine than I was able to reach. Will peruse again this coming w/e. I already checked through the removable storage hold. Couldn't see much. The plywood bulkhead is positioned such that you can't see in. An earlier post suggested using a cell phone to take pictures. I'm going to do that this w/e once I get the water heater out. You are right, it would take a triple jointed miniature contortionist to reach it. Because things seem to be relatively snug I'm becoming suspicious of the scupper hose. If damaged it would be a logical escape route for the exhaust gasses. I started this adventure by checking through the quarter berth. Couldn't see anything, that I could see, out of place or damaged.
To access the mixing elbow will have to be accessed by removing the wood panel on the starboard side if the engine. If that proves to be a problem, I can fix it then.
In your 285 post you mentioned that you noticed a loss in speed. My boat has always run at about 6.4 to 6.6. It has never run above that. In fact I've never had power problems, just battery when running the autopilot over long distance races. To help that I am changing to lcd's and carrying a generator. Beyond that just wrapping the headsail around the rollar furling. I'm sure there is more to come.

 

[Michael1974]

Wrench bender,

Sorry about your undoing, some older boats used to take water from one side of the keel and return it through a port on the other side. My grandfather had a Chrysler runabout and even older sailboat designed as such. I do in fact have a water injected muffler. As I stated earlier I couldn't see any water inlet into it. I wouldn't expect to see diesel exhaust soot float heavily in the air and deposit on a wall a distance from the exhaust exit after the exhaust has gone thru water.
Again, Sorry for your undoing. I'll be more careful in the future.

 

[Dan Hill]

No worries Micheal

The strange thing is your exhaust leak without water also leaking. I'm starting to think you may have an exhaust manifold gasket leak, which is before the mixing elbow.

Good luck with your search.

Dan

 

[Michael1974]

Red,

Good idea. I will do that this w/e once I get the water heater out of the way so I can get near it. I've used the phone to get bar codes before but hadn't thot of using it with this problem. Oh yeah, to drop it would be tragic. It would be gone forever and all of my memory, read brains, would be also lost.

Thanks for your input.

Mike

 

[jtm]

Mike-

I have an 85 28.5. This was an early build- and Hunter changed some construction techniques as some designed-in defects came to light.

The early 28.5 had a molded-in (TV dinner pie plate) recess for the exhaust box and the adjacent fuel box. they then placed a fiberglass board over the top of them- and as it happened with mine on delivery I found that I was suffering constant water contamination in my fuel. It took a summer of back and forth with the dealer and eventually Hunter when they cut the cover top off the 2 recesses and inserted 2 separate containers- one for the "bubble box" and one for the fuel. the top seam separating the 2 was faulty allowing the water to mix into the fuel recess. Once the separate boxes were inserted the problem was solved. Other peoples boats had this seam open up years later.

Perhaps if you are finding exhaust residue in the locker you may have a crack or seam opening up as the engine heats the water and the hot gases get to the rubber and fiberglass cover opens up?? Just another thought.

 

[49North]

I have an 87 28.5 that also has a slight exhaust smell , so I'm following this post. I wonder if it might have anything to do with the wet exhaust hose under the cockpit hatch. Mine shows cracking on the top side where it rises highest. Maybe fumes can exit but not water ?