I am calling on you fellow sailors to help me diagnose a potential Yanmar problem. Late last season, just before winter layup, I had the boat out and I heard an unfamiliar sound coming from my 3HM35F. It was like an abrasive, raspy sound coming from the front of the engine. I forgot about it and when I recommission the engine last week and started it up, I was promptly reminded of it again. I can't tell if it's the alternator or the engine water pump making the "raspy" sound while it's running because they are driven by the same belt and are adjacent to one another. I have a spare alternator that I can install which will identify which unit is making the noise. But has anyone experienced this? I suspect it is the bearing beginning to fail on the water pump, but wanted to seek an opinion. Thanks.
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Don Alexander
Suggestions
Paul, First check the tightness of your anti-vibration engine mounting nuts. Next try removing the alternator belt and running the engine briefly. It will be okay for a minute without cooling if cold when you start up. Also, with the belt removed, you can turn both pump and alternator pulleys and feel if there is any roughness. It could be something simple such as a loose alternator or its adjusting stay. Hope you find it. Don
Paul, First check the tightness of your anti-vibration engine mounting nuts. Next try removing the alternator belt and running the engine briefly. It will be okay for a minute without cooling if cold when you start up. Also, with the belt removed, you can turn both pump and alternator pulleys and feel if there is any roughness. It could be something simple such as a loose alternator or its adjusting stay. Hope you find it. Don
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Ed Schenck
Variation.
Don's on the right track. And I think you are right, it is the waterpump. But if you could find a short belt to just drive the alternator you would get a better test. You probably cannot find a belt just for the waterpump. If like mine the only belt adjustment is with the alternator. I plan to add a pulley to the front of my crank pulley and drive the waterpump with it's own belt. The current arrangement requires too much belt tension for the alternator which is hard on the waterpump. I just bought a new one for that reason, $225. !!
Don's on the right track. And I think you are right, it is the waterpump. But if you could find a short belt to just drive the alternator you would get a better test. You probably cannot find a belt just for the waterpump. If like mine the only belt adjustment is with the alternator. I plan to add a pulley to the front of my crank pulley and drive the waterpump with it's own belt. The current arrangement requires too much belt tension for the alternator which is hard on the waterpump. I just bought a new one for that reason, $225. !!
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Paul Akers
Thanks, Guys...
...Yes, the alternator takes a beating, probably due to the tension. This is the third alternator that I've had in 8 years. One time it simply burned up when a bearing let go. Another time, 2 seasons ago, it stopped generating and I had it rebuilt. That's when I bought the spare. I'll try putting the spare on. If the noise goes away, then I'll know it's the alternator. If I still hear the noise, I'll know its the water pump. I like the idea of the separate pulley for the alternator. One precaution that I take in the winter during layup is to relax the belts to avoid a constant tension on the pulleys. As in cars that are stored, I beleive that that could contribute to premature failure of bearings. Thanks, again. It anyone else can offer advice, I'll be glad to take it. I hate to tear down part of the engine if I can help it.
...Yes, the alternator takes a beating, probably due to the tension. This is the third alternator that I've had in 8 years. One time it simply burned up when a bearing let go. Another time, 2 seasons ago, it stopped generating and I had it rebuilt. That's when I bought the spare. I'll try putting the spare on. If the noise goes away, then I'll know it's the alternator. If I still hear the noise, I'll know its the water pump. I like the idea of the separate pulley for the alternator. One precaution that I take in the winter during layup is to relax the belts to avoid a constant tension on the pulleys. As in cars that are stored, I beleive that that could contribute to premature failure of bearings. Thanks, again. It anyone else can offer advice, I'll be glad to take it. I hate to tear down part of the engine if I can help it.
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Ricky
Mechanic's Trick
If you have the room to do it SAFELY, take a long screwdriver and place the metal end against each suspected part. Then place the other end against your ear. You will be able to isolate the source of the noise very accurately this way. It sounds primitive but it really works. Again, do this only if you can do it SAFELY. The longer the screwdriver, the better for SAFETY. Did I mention doing this SAFELY?
If you have the room to do it SAFELY, take a long screwdriver and place the metal end against each suspected part. Then place the other end against your ear. You will be able to isolate the source of the noise very accurately this way. It sounds primitive but it really works. Again, do this only if you can do it SAFELY. The longer the screwdriver, the better for SAFETY. Did I mention doing this SAFELY?
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Paul Akers
Good idea, Ricky
Boy, that's an old trick that I forgot about. I will assess the safety factor and take a look. Thanks for the info. I spoke to the mechanic at the marina today and he suggested to remove the belt and hand-turn both components. I may feel the drag and isolate it that way. But he, too, suspects the fresh water pump. Changing the fresh water pump is the same a doing it in a car. The pump is a lot smaller. It's been a number of years, but I can still remember
Boy, that's an old trick that I forgot about. I will assess the safety factor and take a look. Thanks for the info. I spoke to the mechanic at the marina today and he suggested to remove the belt and hand-turn both components. I may feel the drag and isolate it that way. But he, too, suspects the fresh water pump. Changing the fresh water pump is the same a doing it in a car. The pump is a lot smaller. It's been a number of years, but I can still remember
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Paul Akers
Did the Screw Driver trick...
...today and there's no doubt that the water pump is failing. I'm having the yard price one for me. I also called on one at a Yanmar supplier. The price will be in the $180 range w/o the gasket. So I figure two boat-bucks by the time I'm finished.
...today and there's no doubt that the water pump is failing. I'm having the yard price one for me. I also called on one at a Yanmar supplier. The price will be in the $180 range w/o the gasket. So I figure two boat-bucks by the time I'm finished.
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Ed Schenck
W/O the gasket?
Why would they sell a pump that was not complete? My new Jabsco, model #2760?, only required that I install the pulley and the two hose connectors from the old pump. I also bought the rebuild kit for the old one but it is just the seals and gasket, no bearings. The bearings are available however.
Why would they sell a pump that was not complete? My new Jabsco, model #2760?, only required that I install the pulley and the two hose connectors from the old pump. I also bought the rebuild kit for the old one but it is just the seals and gasket, no bearings. The bearings are available however.
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