Post Number: 25
|Posted on Sunday, May 06, 2012 - 11:19 pm: ||
I have a P60 in an old New England Catboat on the Finger Lakes running fresh water cooling, with a wet exhaust system. I started it this spring and noticed that the sound coming from the exhaust sounded very tinny and almost hissing compared to last year. It always had a great throaty sound that even other people commmented on. I have been trying to diagnose the change and am concerned that it may be a symptom of a problem.
So far, everything I check seems to be ok. To make sure it wasn't a cooling problem, I have checked the water flow and pressure at all the hoses, and replaced the thermostat. There is goo flow of water at the exhaust port. I also checked the oil pressure to ensure it wasn't a lot of engine noise from no lubrication. It runs with 20-25 lbs of oil pressure at 1/2 speed, which I believe is strong.
I now suspect it may be some change in the exhaust system, such as a restriction in the pipe. I am interested learning if anyone has knowledge of a system of similiar design of a wet exhaust system used with a Palmer P60. I did see a post with a design that could be used, but that didn't really help.
Some background: It is a jacketed muffler system, with the exhaust pipe dropping at about 15-20 degrees down as it leaves the exhaust manifold. The water overflow hose then connects to the first of two water jackets a few inches lower. After a couple of more feet, the water jacket ends and the pipe takes a 60 degree or so bend upward. The second water jacket starts a couple of inches after. A hose connects the end of the first water jacket to the beginning of the second. The pipe then continues to rise until it gets to a goose neck rising straight up for a foot or so then straight down for a foot, and then curves back to level out to the thru-hull exhaust port.
So I have a couple of questions: Is the exhaust pipe typically a straight-through pipe, or is it muffled with baffles or similar? (I recall reading somewhere that it should be a straight-through pipe). I gently probed the pipe from the exhaust manifold side, and there is definitely something blocking the flow. Again, it sounds like the exhaust flow is restricted and is hissing past a small opening. Not sure if a typical exhaust system has baffles or smaller openings that may have gotten clogged.
Second question: since it always sounded more like the exhaust was bubbling through water and now it doesn't, I was wondering where the water is allowed to enter the exhaust pipe from the water jackets.
I'm pretty sure that there is no "standard" exhaust on Palmer engines, but if anyone is familiar with a system as described, I'd appreciate any advice... on the possible cause of the sound changing or the exhaust system. Thanks in advance! -Matt