Outboard exhaust query

[Joe_Cole]

My outboard, a Mariner 8hp Sailpro, sits in a well on my boat. The bulk of the engine exhaust goes out through the prop but there is also a small exhaust vent near the cylinder head which makes a bit of a pong when we are going along and also sets off the Carbon Monoxide alarm down below.

Somebody suggested rigging up a pipe to take this "secondary" exhaust clear of the cockpit and this has proved to be successful, getting rid of the smell and the continual gas alarms without adversely affecting performance. However, I have only rigged this up as a temporary measure and before I make it permanent I would like to know if I am likely to cause any damage to the engine. On the basis that the vent has been put on the engine for some reason (to reduce back pressure when starting the engine or on tickover perhaps?) I would like some advice. (I spoke to the Importers a while ago but, frankly, didn't get much help)

Ideally I would take the pipe straight down to the water (the easiest route) but I could fit a vent out through the transom. (Fiddly, and I hate drilling holes in my hull)

Any thoughts?

Ta.

Joe

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[Andy_Hampton]

Joe
Sorry no answers but I too have the same problem with the Mercury Sailpower 8 (I this may be suspect the same engine) in the well of my Achilles 24. This is currently solved by a length of plastic pipe run to the pushpit, but I look forward to seeing if someone can suggest a more elegant solution.
Andy

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[quaelgeist2]

We had a Mercury 9.9 in a well on a Feeling 720 (similar to First 24/25).

After cold start and in tickover, we always had nasty exhaust fumes coming out of the well and settling in cockpit and cabin.

I have talked to Mercury mechanics and other boaters and got only one relevant advice: This outlet needs free flow for proper operation in tickover or idle - no backpressure.

I took
- a plastic (B&Q) elbow connector (the cheap type, usually coming in white) -> that could be forced into the outlet hole and would stay in
- some 80cm of flexible clear tube/hose from same supplier (6 or 8mm diam. - fitting the connector) pushed it on
- a 10 cm rigid tube (aaprox. 8mm diam. which I fitted inside an existing draining hole of the cockpit/well, connected to the flexible part
- some 2pack epoxy putty fixated the connecter permanently to the outboardleg

This arrangement may sound a bit whacky, but it worked perfectly for the three years we had the boat. I had to redo the epoxy putty once, and then did so again to be safe at the beginning of each season.

pm me if you have any questions
chris

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[steve_cronin]

My solution was.....

.. an adaptor made from a piece of anodised aluminium rectangular section tobe stopped off at one end with epoxy putty. Then after it had hardened I screwed it to the outboard (Honda 7.5) by drilling the leg just above and just below the outlet. A gasket was made of neoprene rubber sheet (any dinghy repair patch will do). Two holes were drilled through the tube at the same centres as the leg holes (which were 5mm tapped) and before attaching, the tube was bent so as to clear the leg. to the free end of the tube (which pointed down) was attached a length of 1/2 in car heater hose. This was actually a Ford Fiesta heater hose which, having two right angle bends in it allowed a good deal of flexibility. The other end of the hose was attached to a 1/2 in skin fitting in the transom which was positioned so as to always be above water level.

The set-up worked perfectly and we had that boat seven years doing many channel crossings under power including one trip right down to St Malo, through the Isle et Rance canal, out into the Atlantic and up to the Gulf of Morbihan again all under power and back again. No engine problems at all and no smells in the boat (a Newbridge Venturer)

Steve Cronin

<hr width=100% size=1>The above is, like any other post here, only a personal opinion

 

[Joe_Cole]

Re: My solution was.....

Thanks Guys! It looks like I'll be getting out the epoxy putty and making my temporary pipework a bit more permanent!

Joe

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