A25 exhaust system

[sail149]

Hi
I think you should be looking at sailboat type exhaust set ups.they have the same problem, engines low in the hull.
It looks like the elastomufflle was added without shortening the hose when they changed the engine .
Did you say which engine you have and have you looked at that engine manafacturers website to get their advise on a sailboat set up?

I tried to find elestomuffle for sale and could only find one product called a transom mount. With only one picture and no installation diagram.
You must have a water trap installed somewhere in the exhaust system . You can run without one but boats sink without them!
This outfit has some good advise
http://www.sbmar.com/articles/designing ... st-system/
And the Ventus site has a lot too.
The A25 handbook shows the exhaust running down hill from the thru hull direct to the engine ad21
, wow this is really bad , did the ad21 have SOMTHING special built in?i doubt it.
What have the Europeans done over the years they have way more over there than here.

[sail149]

WilleC, check the wattage of you invertor. I found the small ones are ok for running fan or a small laptop charger but my 300w one would not run a battery charger for a drill. A 3 amp draw will blow fuses . For ref a 15 amp house Curcuit at 110V is 1650 watts. So that many amps would need a 2000watt inverter. (Watts= Volts X amps).
FYI harbor freight had cheap inverters if you ignore the not for marine use label!

[sail149]

Kerrye
I assume you have checked out exhaust set up advise available
Like this from beta marine
http://www.betamarinenc.com/index.php/r ... ust-design
As I see you problem is getting a gooseneck loop into you system after a waterlift installed in the small engine space, but not interfere with the aft cabin space.
Can you run a hose from the waterlift outboard to a locker and put a gooseneck (or anti siphon loop) in there and then run the hose back to the orriginal outlet on the transom. ( side exhausts can have problems with fumes).
There are ready made gooseneck to simplify installation.

[kerrye]

The problem with a waterlift system is finding a place to put a waterlift muffler with enough capacity to hold the water in the hose. My A25 (and probably most if not all A25's) don't technically need a waterlift muffler since the exhaust manifold is above the waterline. But it's not by much, just 6" in my case. The other problem is that the thru hull needs to be right at the waterline since there's only 6" to play with. Raise the thru hull and it's likely you will get water backing into the engine (unless you use a waterlift system) The low thru hull results in the exhaust hose being filled with seawater up to the waterline all the time and considerable consternation should that hose be breached. I do think the check valve is a good idea. I've also ordered some softwood plugs so I can stick one in the thru hull should I face this situation again.

[kerrye]

I suspect the Elastomuffle was original to the boat which probably contributed to its failure although it showed no signs of perishing.

[WillieC]

I think Kerry is getting close to replacing his ancient muffler and pretty much going with the original. Warren, thanks for the schematic, nice to have all this info in the same thread, though the A25 manifold is above the waterline, barely. Kerry has nailed it with space constraints, sacrificing the side berth, volume of waterlft etc, etc. My throughhull is halfway under/inline with swim platform which makes jamming a plug into it from the outside tricky. From the inside requires removing floorboards. I am leaning toward a brand new through hull and shutoff at the stern, providing ready access for it, and leaving the rest of the system as is. Both waterlifts and check valves add back pressure which may or may not be problematic. The checkvalve, though simply a rubber flap, may be subject to fouling gunk which may be difficult to maintain or even ascertain. The prehistoric MD3B is running so sweet, I don't want to mess with it.
Many motorcyclists use front disc wheel locks to slow down thieves. Jumping on the bike and attempting to drive off while forgetting your brilliant scheme to foil criminal activity is fraught with peril. DUMP! So, many of us have disc locks with a plastic coil that wraps up over the handlebar to remind the owner to remove the lock. I have simply put a piece of electrical tape over my ignition switch when using the lock. I am thinking you could secure a small roll of tape to the 2" throughhull shutoff. Cut off a chunk when you close it and stick it over your ignition switch, and don't let anybody interrupt you while doing this simple step. I would also have to consider curious grandchildren fooling around in the aftcabin if the valve is too accessible.

[2manyboats]

I tried to send pics but they were to large. I'll send a pm with my e-mail

[sail149]

2manyboats re photos,
Hi I had trouble sending photos that are too large, but found when I send from my iPad , which I do most of the time , if I send from my 'photo stream' rather than the 'camera roll' the photos are smaller and work. You may be sending from something else so might not work. Also uploading each seperatly can help too.
Just a thought.

[sail149]

Kerry
Your suggestion to use
http://www.defender.com/product.jsp?pat ... id=2051557
Is a good one, it will be fairly close to the engine and hold water whichever way it's going and the gallo capacity is good and it will fit without major changes.
Try checking out the Ventus web site they have lot of imformation
http://www.vetus.com/exhaust-systems/wa ... r.html?p=2

[kerrye]

By the way, I checked the Westerbeke manual and it says for above the waterline installation, exhaust manifold should be a minimum of 6" above the waterline.

[WillieC]

Kerry,

Here is my setup. 1-3/4” hose all the way. It works, so far. Seems last section of hose may drain to outside with slight rise, but as you note, other side of loop will also raise the potential amount of water toward the exhaust manifold. Waterline was determined by hanging a straight stick over the gunnels and transferring that measurement inside. Boat is lightly loaded so that will change some. About all I will improve is to add a shutoff right inside the discharge. Outlet is below swimstep, difficult to reach, and at rest is about half submerged at waterline. Tried to get decent picture but wind drug me away too quickly. Hope this helps.

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Edit: so I check Centek and I "should" be using 2-1/2" inlet and outlet for this 36HP diesel engine. Oh well, exhaust elbow is 1-3/4", so is through hull. This is the muffler Desert Albin Steve posted. Rick

[kerrye]

Your layout is very similar to mine except mine is 2" hose and since manifold is on the port side of the engine it crosses over aft of engine to starboard side.

[DesertAlbin736]

Your layout is very similar to mine except mine is 2" hose and since manifold is on the port side of the engine it crosses over aft of engine to starboard side.

I wonder why Albin decided to move the exhaust through hull from port side in the early models like our 1971 to starboard side in later years? I guess because Volvo engines had starboard side exhaust manifolds? Now you have a port side manifold crossing over to starboard side exhaust through hull, while I have a starboard manifold crossing over to port side exhaust through hull. It's part of what makes the A25 interesting, all the different internal variants out there on boats with the same outward appearance.

[kerrye]

New heavy duty hose clamps arrived yesterday so I connected the exhaust without a muffler and ran it for a while (long enough to suck 10 gallons of water thru it). It ran fine and I noticed no difference in sound from when it had the muffler on it, although I wasn't running it under load. But also the exhaust hose wasn't filled with water either.

I did realize that there is a reason why this problem occurred for me and not for the owner who installed the new engine. He lived in Maine at sea level and I live a mile high. There's less atmospheric pressure here so the engine will shut down faster from backpressure than at sea level. Also there's less atmospheric pressure to resist the expansion of the Elastomuffler to its explosion point.

[WillieC]

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