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I-33 10-10-2006 01:52 PM

Marine Exhaust System Literature
Can anyone make recommendations for learning about marine exhaust systems? I'm a hands-on type that has next to zero knowledge in this area. I want to know how to maintain mine while minimizing the financial drain. Thanks, Gil

jgeltz 10-11-2006 08:14 AM

Check out Nigel Calder's books on Marine Maintenance.

jtommins 12-16-2006 11:41 PM

Marine- exhaust
Calder's book is good. So is Don Casey's This Old Boat- a good section on dry/wet exhaust with water-lift mufflers.

I just replaced the dry exhaust riser and wet stack on my A4 with a few specialty parts from Moyer Marine ( also a good souce of info), and about $40.00 of pipe from Home Depot. Pretty straightfoward ( except for contortions in the engine room!) Did it over a few weekends.


billangiep 12-17-2006 05:45 AM

This is also a very good read, from good old boat....

roland693 12-17-2006 06:31 AM

Our exhaust system
We've had only two problems with our exhaust system while cruising. One, in Puerto Rico where the 1 1/2-inch threaded pipe rusted through and blew off just as were leaving Boqueron for Salinas. We sailed the rest of the trip and found a local welder (charged us $10, but we gave him more).

The second problem happened in Trinidad just before leaving for Tobago. The stainless flexible pipe between the engine manifold and the muffler cracked and leaked exhaust. We learned that most good auto muffler shops can replace this pipe (we got lucky, only about $100 USD including cutting and welding).

Otherwise, check water and exhaust hoses and clamps regularly.

jgeltz 12-17-2006 10:04 AM

Whatever you do - don't forget the anti-siphon loop. The person who previously owned my boat had the yard install a new exhaust elbow. They didn't put in a valve. One morning I went to check the oil before starting the engine and water came squirting out of the dipstick hole for 10 minutes filling the bilge. Talk about a heart stopper!

I installed a Vetus valve from Defender along with some exhaust tubing and all is well.

Valiente 12-18-2006 01:05 AM


Originally Posted by jgeltz
I installed a Vetus valve from Defender along with some exhaust tubing and all is well.

I have what I have been told is a near perfect exhaust installation lacking only an exhaust outlet stopcock to avoid siphoning in the sea when on a heel. And yet I got water in my valve chambers several times this season, wasting lots of hours in oil changes, filter changes, kerosene flushes, backstrain from pumping and detective work. As I have closed loop cooling and a heat exchanger, it was either the raw water pump (nope, but I changed the gaskets and impeller while it was off, the heat exchanger or the oil cooler/transmission circuit. As there was no change in the level of the coolant, nor was there any sign of water in the tranny fluid, I decided to look elsewhere. Eventually I determined that the valve in my nice and high anti-syphon loop (a Scott's, I think) would intermittantly STICK in the upright position, which didn't allow the siphon to break, and did allow water to rush back into the exhaust, rather than down into the waterlift.

Goddamnit. A plunger and a spring worth pennies has cost been a few hundred in oil, filters and angst. The boat's new to me, but I had a somewhat similar issue when a waterlift muffler failed on my previous boat's Atomic 4. Drove me nuts. Then I got a Vetus waterlock, got it nice and low vis a vis the exhaust elbow (right at the waterline) and my oil ages to a nice browny black instead of a horrible gray milkshake.

Back on the new boat, I have been advised to try the Vetus, but I am leaning toward the more bulletproof method of running a plain hose straight up into the pilothouse or into the cockpit. You could even run it so it "peed" a bit off the side, providing evidence you've got flow when your exhaust itself is under the surface. Shut down, and the air is always there and you hear the British toilet-type gurgling of water going into the lift, not into your diesel.

georgellop 12-18-2006 08:53 AM

.... for a great schematic on what an exhaust system should look like click on the exhaust page of the index bellow and move down the page. Click again on the schematic and you'll be able to see details.

eastbaydave 04-24-2007 01:00 AM

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