Strange sound coming from engine.


Old 03-12-16, 08:15 PM
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Strange sound coming from engine.

I have a 1995 Honda Civic EX, with the 1.6 liter VTEC engine. The engine is making a strange sound. When I lean over the engine, while it is running, I can hear the sound coming from the alternator, or right close to it. It is a whining, buzzing sound. It is kind of harsh. When I rev the engine, the pitch of the sound changes. It is loud enough to hear when I am driving. The engine seems to be running fine. No warning lights are on. With the engine off, I grabbed the belt that drives the alternator, and pushed and pulled it. It seems to be fairly tight. The belt appears to be fairly new, and in good condition. I am wondering about the alternator. Could the bearing in the alternator be wearing out? If that is happening, how long can I let this go before something bad happens?
Old 03-12-16, 09:38 PM
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It could be the bearings in the alternator or the bearings in a nearby idler pulley that the belt rides on. If the sound is loud enough to be obvious..... it should be serviced as soon as possible.
Old 03-13-16, 05:39 AM
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You may can zero in on the sound by using a piece of tubing sort of like a stethoscope and placing it near the alternator and idler to see exactly which one is going south. As Pete says, it needs attention soon.
Old 03-13-16, 08:22 AM
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Oh the infamous alternator noise..... One of the most common Japanese cars noises.
OP, do you have voltmeter? To test alternator output? That is what I'd be concerned about.
Thing is, those alternators can run with noise for years more. Same time, bad bearing will reduce alternator output.
As others said - pin point noise. Tubing, length of garden hose, or mechanic stethoscope from Harbor Freight. Couple bucks and on 20 year old car will be used frequently anyway.
Also, keep in mind that for the age, brushes on alternator may be down to nothing. Unless you have a brushless one... Brushes are replaceable item. 6 or so bucks and boom, new alternator.
Do twist test for belt. Not what you did. It's either twist or deflection test.
Report back.
Old 03-13-16, 08:54 AM
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At least he didn't have what I had last week on my 1955 Ford 640 tractor. Tracing down why battery kept dying. All wiring was OK. When I attached the negative cable I heard a click like a relay. No relays on this monster. But I did note the alternator jumped. Took the belt off and the alternator became a motor when I hooked the negative to the battery. Burned out diodes.

Fun part came when OReilleys and Auto Zone tried to test it. They kept asking what it came off of. Gee. Have they never seen a one wire GM alternator?? Their computer driven tester had to know.

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