Over the past 6 months I have noticed the exhaust seems a little bit louder than before. Yesterday, after being in another boat with the same engine I am sure something is a miss. Everything looks OK with no leaks either water or air. The engine, a 1986 universal M-18 runs fine but when I crank it it sounds hollow at the stern with kind of an echo. The noise doesn't come from the engine itself. If I were to guess I would say the baffle in the muffler came apart. Of coarse I doubt the muffler has baffles so that can't be the case. How does the water muffler work and how can I check to see if that is the problem? Thanks, Jack
Muffler noise?
- Thread starter Jack2438
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Water Box
It's basiclly a box filled with water, exhaust is mixture of hot gas and cooling water. Pressure from the mixture forces the efluent out discharge port. Sounds like the mufler is not holding water and you are hearing he hollow sound of the exhaust gas expanding in the chamber. Any signs of a leak?
It's basiclly a box filled with water, exhaust is mixture of hot gas and cooling water. Pressure from the mixture forces the efluent out discharge port. Sounds like the mufler is not holding water and you are hearing he hollow sound of the exhaust gas expanding in the chamber. Any signs of a leak?
Bob
I will double check but the last time I looked it didn't appear to be leaking at the "box" and the water/exhaust flow seemed normal at the stern. I think your on to something. Has anyone ever replaced the water muffler? How much $ for the m-18? thanks, Jack
I will double check but the last time I looked it didn't appear to be leaking at the "box" and the water/exhaust flow seemed normal at the stern. I think your on to something. Has anyone ever replaced the water muffler? How much $ for the m-18? thanks, Jack
It works like a perculator
but instead of steam pushing the water through the tube it is exhaust doing the pushing. A lot of hollow sounds can come from tubing routing. Kinda like playing an instrument. change the length or the shape just a little and you get a different note. Most are fiberglass and have no user servicable parts. I have never heard of one going bad either.
but instead of steam pushing the water through the tube it is exhaust doing the pushing. A lot of hollow sounds can come from tubing routing. Kinda like playing an instrument. change the length or the shape just a little and you get a different note. Most are fiberglass and have no user servicable parts. I have never heard of one going bad either.
Muffler Noise Increasing Problem
I had a similar problem with my 1987 Catalina 30's Universal 21 hp diesel's muffler three years ago after about 600 engine hours. I eventually found that I had a hairline crack in the fiberglass wet muffler. The crack was where the exhaust pipe feeds into the muffler. Catalina had exact fit replacement mufflers in stock, so I ordered one through my boatyard, Riverfront Yacht Services, and at the same time they suggested I replace the stock cast iron pipe from the exhaust with a flexible stainless steel wrapped rubber exhaust hose designed for diesel trucks. That in turn was wrapped with a cream colored insulating fabric. The root cause of the crack was the vibration from the engine transmitted through the rigid cast iron exhaust pipe. I think the boat now has a far superior exhaust system than when the it was new. It is quieter, the exhaust pipe gives off much less heat, and it looks better. Engine vibration transmitted to the muffler has dropped significantly. Riverfront told me that they had done this type of upgrade/repair many times before and said it should last up to 10,000 engine hours. I believe them. I am now at 900 engine hours and there are zero problems. The yard did all of the work. Parts and labor cost me around $700 if I remember correctly.
I had a similar problem with my 1987 Catalina 30's Universal 21 hp diesel's muffler three years ago after about 600 engine hours. I eventually found that I had a hairline crack in the fiberglass wet muffler. The crack was where the exhaust pipe feeds into the muffler. Catalina had exact fit replacement mufflers in stock, so I ordered one through my boatyard, Riverfront Yacht Services, and at the same time they suggested I replace the stock cast iron pipe from the exhaust with a flexible stainless steel wrapped rubber exhaust hose designed for diesel trucks. That in turn was wrapped with a cream colored insulating fabric. The root cause of the crack was the vibration from the engine transmitted through the rigid cast iron exhaust pipe. I think the boat now has a far superior exhaust system than when the it was new. It is quieter, the exhaust pipe gives off much less heat, and it looks better. Engine vibration transmitted to the muffler has dropped significantly. Riverfront told me that they had done this type of upgrade/repair many times before and said it should last up to 10,000 engine hours. I believe them. I am now at 900 engine hours and there are zero problems. The yard did all of the work. Parts and labor cost me around $700 if I remember correctly.
Jack you describe exactly the situation I had
My engine started getting louder and sound pitch changed and the sound was aft of the engine. I thought the muffler was going bad. Then about 20 engine hours later, the mixing elbow clogged up. One day when I started at the dock and checked the outflow, there was none. I didn't notice any reduction in the raw water flow, but when the elbow was replaced I saw the volume difference. Of course it could be the muffler. Scott
My engine started getting louder and sound pitch changed and the sound was aft of the engine. I thought the muffler was going bad. Then about 20 engine hours later, the mixing elbow clogged up. One day when I started at the dock and checked the outflow, there was none. I didn't notice any reduction in the raw water flow, but when the elbow was replaced I saw the volume difference. Of course it could be the muffler. Scott
replaced water muffler
on my M-18 engine last spring, you'll all love this one. In the fall of 2005 my engine made the same noises, checked the impellers on the raw water pump and they looked ok I just wasn't getting enough water thru the exhaust. Shut the engine down and sailed as close to the marina as i could and used the engine to get in and dock. We over heated but not by much, as we reached the dock. The next day I checked over the entire engine and here's what I found, the impellers were stuck in the pump and in perfect condition but the internal ring that has the keyway to the pump shaft was plastic and was melted,so the shaft turned but the impellers didn't. Also the water muffler had melted at the inled exhaust conection and also blew a hole thru the side of the muffler. I fixed the muffler with epoxy and the hose connection with that magic tape (stuff really works) and I replaced the impeller with one that had a metal sleeve in it. Being the end of the season I had to move my boat 1/2 mile to have it pulled for the winter and it ran great pumping all kinds of water. I went to wm and priced the waterloc muffler $69, thought I'll wait till spring and get it then and take the whole exhaust system apartand check it over.Nice move WM that $69 went to $89
on my M-18 engine last spring, you'll all love this one. In the fall of 2005 my engine made the same noises, checked the impellers on the raw water pump and they looked ok I just wasn't getting enough water thru the exhaust. Shut the engine down and sailed as close to the marina as i could and used the engine to get in and dock. We over heated but not by much, as we reached the dock. The next day I checked over the entire engine and here's what I found, the impellers were stuck in the pump and in perfect condition but the internal ring that has the keyway to the pump shaft was plastic and was melted,so the shaft turned but the impellers didn't. Also the water muffler had melted at the inled exhaust conection and also blew a hole thru the side of the muffler. I fixed the muffler with epoxy and the hose connection with that magic tape (stuff really works) and I replaced the impeller with one that had a metal sleeve in it. Being the end of the season I had to move my boat 1/2 mile to have it pulled for the winter and it ran great pumping all kinds of water. I went to wm and priced the waterloc muffler $69, thought I'll wait till spring and get it then and take the whole exhaust system apartand check it over.Nice move WM that $69 went to $89
Additional
after reading Scotts response it would make sense that if for some reason you weren"t getting the proper amount of cooling water through your system, the water lift muffler may not have the proper amount of water in it to start with. Thus in lieu of a leak you may have a flow problem. Check your raw water pump and mixing elbow.
after reading Scotts response it would make sense that if for some reason you weren"t getting the proper amount of cooling water through your system, the water lift muffler may not have the proper amount of water in it to start with. Thus in lieu of a leak you may have a flow problem. Check your raw water pump and mixing elbow.
Easy method to check raw water block
I learned this the hard way. First checked sea strainer. Second I took the raw water impeller out, it faced aft and you have to take the alternator off, replaced it with a spare. Project took two hours. Still no water out the exhaust pipe in the transom. Scratched my head, then disconnected the raw water hose from the mixing elbow, 2 minute job, started engine, water gushed out of hose end. So I knew it was the elbow. Could have saved a couple hours and some knuckles.
I learned this the hard way. First checked sea strainer. Second I took the raw water impeller out, it faced aft and you have to take the alternator off, replaced it with a spare. Project took two hours. Still no water out the exhaust pipe in the transom. Scratched my head, then disconnected the raw water hose from the mixing elbow, 2 minute job, started engine, water gushed out of hose end. So I knew it was the elbow. Could have saved a couple hours and some knuckles.
OK, I'll look at the mixing elbow
Does anyone have a dealer in mind with good prices? {M-18 engine.} What is a guess on labor hours to install? thanks, jack
Does anyone have a dealer in mind with good prices? {M-18 engine.} What is a guess on labor hours to install? thanks, jack
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