On our way to Block Island last week we started to hear an intermittant squeel coming from our M25 diesel. It sounded similar to the sound of a bad bearing that you sometimes hear in an auto heater blower motor before it fails. Changed RPMs and the squeel went away for awhile but soon returned. Checked the fan belt and it seemed OK. I was not able to tell whether or not the squeel was coming from the fresh water cooling pump, the alternator or the sea water pump.Too much engine noise. Even tried the old listen via a screwdriver trick but still could not isolate where the sound was coming from. We cut our trip short just to be safe. Any ideas on how to isolate where the sound is coming from would be appreciated,I don't want to replace the wrong component. Thanks Marc P
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Isolation
What I would do: 1. Remove the belt and try the bearings on the circulating pump and alternator by hand. 2. Run it for a few minutes without the belt. 3. Remove the seawater pump and run for a few minutes. It is much more likely to be a circulating pump or alternator bearing than anything else, if its coming from the front of the engine. jv
What I would do: 1. Remove the belt and try the bearings on the circulating pump and alternator by hand. 2. Run it for a few minutes without the belt. 3. Remove the seawater pump and run for a few minutes. It is much more likely to be a circulating pump or alternator bearing than anything else, if its coming from the front of the engine. jv
Squeal
Have you replaced your alternator bracket yet? See the link below. When ours went, there was one heck of a squeal first. John's also right about the different bearings sources. Your choices are the most likely. Any water coming in around the raw water pump?
Have you replaced your alternator bracket yet? See the link below. When ours went, there was one heck of a squeal first. John's also right about the different bearings sources. Your choices are the most likely. Any water coming in around the raw water pump?
Squeal
OK I never said I could spell squeel vs squeal. I stand corrected. Yes I have replaced my alternator bracket but still have the original alternator as far as I know. 985 hours on the engine. I do not have the PSS shaft seal. I will try and isolate the squeal as John suggests this weekend and let you know how I make out. Thanks
OK I never said I could spell squeel vs squeal. I stand corrected. Yes I have replaced my alternator bracket but still have the original alternator as far as I know. 985 hours on the engine. I do not have the PSS shaft seal. I will try and isolate the squeal as John suggests this weekend and let you know how I make out. Thanks
bearing check
When you check, besides spinning the pulleys, put some side pressure on them to simulate the side load the belt causes. These engines, with their pulley set-ups, were never really meant to drive big loads via the belt. They originall had little 35 Amp or so alternators used just to recharge, i.e. top off, the starting battery, and make a little power for the gauges. A bigger alternator requires sometimes more tension on the single belt than the mounting arrangement or the bearings on the other accesories can handle. jv
When you check, besides spinning the pulleys, put some side pressure on them to simulate the side load the belt causes. These engines, with their pulley set-ups, were never really meant to drive big loads via the belt. They originall had little 35 Amp or so alternators used just to recharge, i.e. top off, the starting battery, and make a little power for the gauges. A bigger alternator requires sometimes more tension on the single belt than the mounting arrangement or the bearings on the other accesories can handle. jv
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