I hope to vent the exhaust of my honda 9.9 from the well of my cd 26 (hull #12) in the same way as Dana A. I searched the messages for honda owners and found several who were about to do the work. Has anyone completed the job? I'm not sure how to tap into the exhaust port.
nilesl@algorithms.com
cd 26 outboard exhaust
Moderator: Jim Walsh
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JOHN CHURCHILL
Re: cd 26 outboard exhaust
i have done it. i drilled out the idle port and placed a copper tubing up then clamped a new heavier hose to it. it is not entirely satisfactory as the honda also has an exhaust port on the aft side of the upper housing, whereas Dana's yamaha has the main exhaust thru the prop hub. i have thought of trying to make some sort of adapter so i can fit another hose to the main exhaust, but that is still on the list. p.s. drilling the idle port is much easier with the engine out of the boat. i also did the fresh water flush like Dana. it works great. let me know any other ? if you start or if you make an adapter for the main exhaust.Larry Niles wrote: I hope to vent the exhaust of my honda 9.9 from the well of my cd 26 (hull #12) in the same way as Dana A. I searched the messages for honda owners and found several who were about to do the work. Has anyone completed the job? I'm not sure how to tap into the exhaust port.
jchurchill@erols.com
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jim stull
Re: cd 26 outboard exhaust
Hi LarryLarry Niles wrote: I hope to vent the exhaust of my honda 9.9 from the well of my cd 26 (hull #12) in the same way as Dana A. I searched the messages for honda owners and found several who were about to do the work. Has anyone completed the job? I'm not sure how to tap into the exhaust port.
I purchased and installed an 8hp Honda into my CD25 last year. Before purchase, I had a lengthy discussion of the fume problem in the well with the Honda tech rep at the Annapolis Boat show.
He suggested instead of tapping the exaust a better way would be to duct in fresh air. So in my (then) state of ignorance I proceeded along this path. I cut a 3.5" dia hole in the top cover, machined an aluminum trim ring and riveted this with a screen into the cover. I added a third , forward facing vent into the well cover that sealed to the engine cover with a gasket when the cover was closed. All this work was only partially successful. Sometime the engine would run perfectly other time it would falter.
Closer inspection of the engine showed that, although the engine cover seals to the motor there are numerous voids BELOW the cover. I then sealed the ones I could see with silicone. Better but still no cigar.
Since all my attempts to solve the fume problem by providing fresh air were only partially successful, I had decided to bite the bullet and pipe the exhaust out of the well. BUT, now, with the engine out of the boat, I find this is not so easy. The exhaust port on the lower part of the
engine is a rectangle, long and narrow. Not very easy to collect the fumes into a pipe. It is also siamesed with the water intake. Additionally, there are two tiny holes in the lower casting below the engine head. I studied the situation while I ran the engine in a barrel of water. Exhaust comes out of these holes (ports) also. If I plug these hole with my finger,
during operation, the exhaust from the lower port increases. I suspect most of the problem comes from these upper ports. I hesitate to drill out and tap these holes because I don't know where the chips may go. I purchased the Honda service manual but it makes no mention of these upper ports.
I have studied Dana's pictures very closely in an effort to profit by his solution. Unfortunately, even if I tapped out these holes, I have not come up with a good way to route the hoses on my boat. May be the CD26 has more posibilities. Very close inspection of my engine on the work stand shows that there are still some very large "holes" around the handle/clamp mechanism. These also happen to be just below the carb air intake (which faces down, not up as in a car.) An obvious solution would be to duct the carb air intake directly to the hole in the cover but due to the "hardware" in this path it would be difficult. Sooo, my next step (today actually) will be to seal the remaining voids (except for two very small drain holes at the rear of the engine). I think this should finally completly solve the problem, however my track record on this issue has been faulty!
Let us know what you try.
Jim
jtstull@icubed.com
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Kurt Lyons
Re: cd 26 outboard exhaust
I modified the exhaust relief on my 9.9Honda and CD26 motor well in the following manner and have been very pleased with the results.
1. I removed the lower unit from the engine
2. I plugged the existing idle relief with thickened expoxy
3. I drilled a 1/2" hole in the side of the exhaust housing slightly
below the engine oil drain plug creating a larger capacity relief port
4. I screwed a 3/8" i.d. brass elbow into the 1/2" hole, securing it with nuts and lockwashers. I positioned the elbow facing aft.
5. I drilled another 1/2" hole thru the aft end of the motor well and epoxied a 3/8" nipple in this second hole
6. I connected the 3/8" elbow to the 3/8"nipple with a piece of clear plastic tubing
7. I now have a larger capacity idle relief that directs the exhaust away from the motor well even if the throttle is slightly above idle.
kjlgpw@aol.com
1. I removed the lower unit from the engine
2. I plugged the existing idle relief with thickened expoxy
3. I drilled a 1/2" hole in the side of the exhaust housing slightly
below the engine oil drain plug creating a larger capacity relief port
4. I screwed a 3/8" i.d. brass elbow into the 1/2" hole, securing it with nuts and lockwashers. I positioned the elbow facing aft.
5. I drilled another 1/2" hole thru the aft end of the motor well and epoxied a 3/8" nipple in this second hole
6. I connected the 3/8" elbow to the 3/8"nipple with a piece of clear plastic tubing
7. I now have a larger capacity idle relief that directs the exhaust away from the motor well even if the throttle is slightly above idle.
kjlgpw@aol.com
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Darin Bartram
Re: cd 26 outboard exhaust
I haven't tried venting the exhaust on my CD26 (w/ Johnson 8 hp), but instead have a blower installed in the well to provide more fresh air. A hose is connected to one of the cowlings, and then connected to the blower. This seems to provide enough air for the motor to run well. There are two downsides: (1) the blower takes up enough space in the well that I can use only one gas tank (which, in the end, is enough), and (2) the blower makes noise (of course, so does the motor).
dbartram@hunton.com
dbartram@hunton.com
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Kurt Lyons
Re: cd 26 outboard exhaust
Another modification I performed...
1. drill a 2" hole in the Honda engine cover.
2. mount a plastic thruhull to this hole
3. run a piece of 1 1/2" flexible hose to one of the motor well vents on the CD26 engine well cover
kjlgpw@aol.com
1. drill a 2" hole in the Honda engine cover.
2. mount a plastic thruhull to this hole
3. run a piece of 1 1/2" flexible hose to one of the motor well vents on the CD26 engine well cover
kjlgpw@aol.com
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Larry Niles
Re: cd 26 outboard exhaust
Thanks for your responses to my message. I have questions. Jim, I have also tried to vent fresh air but by removing the baffle on the top cover vent and attaching a dryer hose between it and the outside. I also had little success. My question is what will happen if you seal all the air intake holes when the engine at running speed. Will it get enough air?
My second question is does Kurt's method of tapping into the exhaust housing avoid the problem of multiple ports mentioned in Jim and John's messages? My engine is with my boat on the Chester river and I am in New Jersey, so I can't examine the engine.
Once again thanks, this is very helpful.
My second question is does Kurt's method of tapping into the exhaust housing avoid the problem of multiple ports mentioned in Jim and John's messages? My engine is with my boat on the Chester river and I am in New Jersey, so I can't examine the engine.
Once again thanks, this is very helpful.
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jim stull
Re: cd 26 outboard exhaust
Hi LarryLarry Niles wrote: Thanks for your responses to my message. I have questions. Jim, I have also tried to vent fresh air but by removing the baffle on the top cover vent and attaching a dryer hose between it and the outside. I also had little success. My question is what will happen if you seal all the air intake holes when the engine at running speed. Will it get enough air?
My second question is does Kurt's method of tapping into the exhaust housing avoid the problem of multiple ports mentioned in Jim and John's messages? My engine is with my boat on the Chester river and I am in New Jersey, so I can't examine the engine.
Once again thanks, this is very helpful.
In ref to your question about the engine receiving adequate air with the "holes plugged up".
The concept I was after was to prevent exhaust fumes displacing fresh air. The the vent that I placed in the cover has an area 3 times the area of the carb intake. Unfortunately since the air horn on the carb intake faces down , it sometimes gets flooded with the fumes rising from the exhaust. The problem was less frequent after I sealed off the holes I found while the engine was in the boat. However still sometime a problem. Until I removed the engine, I was unable to see the major voids that are just below the carb intake.
I am hoping that eliminating these will finally fix the problem. We will see.
BTW, I also find the comment from the others on this board very helpful. There must be a couple of hundred years of experience here! Its great not have to start at "ground zero" when working on a problem.
Jim
jtstull@icubed.com