[C320-list] Muffler leaks and drainage

[sail-ability sail-ability]

   If I may beg to differ with the statement below regarding 'unburnt
   fuel'..... unburnt fuel is fuel that has been delivered by the
   injectors(diesel engines) into the cylinders and for one reason or
   another is not completely burnt. It goes out the exhaust and there is
   no way that it can/is  returned to the fuel tank.  The injectors
   however are delivered much more fuel than can be injected into the
   engine. This excess fuel is then redirected to the fuel tank and is
   used to cool the injectors. If you feel the fuel tank after a long
   period of running you will detect that it is quite warm and this is
   why. Check your engine next time you are aboard and you'll discover a
   common fuel line connecting the injectors and leading back to the fuel
   tank.

   Just for the sake of argument.

   JohnM

   1999#574

     ---------- Original Message ----------
     From: jim brown <jbrown5093 at yahoo.com>
     Date: January 14, 2017 at 9:27 AM
     The drain tap certainly could leak water if in the open position
     (screwed out). That's the drain that you're supposed to use if you
     crank the engine for more that 30 seconds before you try again. That
     is to prevent hydro locking of the engine (costly). Won't affect
     anything if it's left open but will drain water into the bilge.
     Not sure why you'd get a raw diesel smell from an exhaust leak. That
     to me smells like exhaust with a little diesel mixed in. I'm not
     sure how much raw diesel fuel gets into the exhaust under normal
     conditions where unburnt fuel is supposed to be returned to the fuel
     tank so it doesn't wind up in the exhaust. Also if there is some
     diesel fuel in the exhaust it would be diluted by the water from the
     aqualift muffler. A leak of fuel, however, would gradually work its
     way into the bilge via the compartment under the sink. Chased a
     small leak in the secondary fuel filter for quite a while on our
     boat. Smell was worse under the sink.
     Jim Brown
     From: Graeme Clark <cg at skyflyer.co.uk>
     To: Catalina list <C320-List at Catalina320.com>
     Sent: Friday, January 13, 2017 2:49 PM
     Subject: [C320-list] Muffler leaks and drainage
     Last summer, after motoring any length of time, we would get a
     diesel fuel smell in the aft cabin and  - i noticed  also - more
     strongly under the galley sink.
     I know I don't have a fuel leak and I know that the exhaust system
     is good as far as the muffler.
     I therefore am assuming either a leak from the muffler or from the
     exhaust hose itself, which is I think the original fit from 20 years
     ago and therefor probably perished!
     So I will be replacing the exhaust hose and have removed the muffler
     to inspect at home. There is no immediate obvious sign of a leak but
     it isn't under any pressure, of course. Any suggestions as how to
     best test it?  Even if it isn't leaking I thought I might take the
     opportunity whilst out of the boat, to reinforce any weaker areas
     with glass mat and resin. But what ARE the weaker areas? I know
     others here have had problems with these mufflers on and off over
     the years.
     Finally, there is what i assume to be a T-shaped drain tap on the
     side of the muffler, but I was surprised to find it in the fully
     unscrewed position (in other words fully counter clockwise). has it
     vibrated open, is that the `leak' - or does this drain valve work in
     the reverse sense to `normal'?
     Thanks in advance for any guidance
     Graeme
     #366, 1996, Oskar, Falmouth UK
     --------------------------------------
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