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  #1   IP: 65.93.38.247
Old 12-24-2017, 06:34 PM
N29sailor N29sailor is offline
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Engine sound varies
Once the A4 is running and warmed up I get 2 to 3 second changes in engine sound at about 10 to 15 second intervals. The sound seems to become deeper and more 'throaty'. Any ideas?
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  #2   IP: 100.36.89.105
Old 12-24-2017, 07:52 PM
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Regulator on the alternator switching on and off, changing the load on the engine?
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sastanley (12-24-2017)
  #3   IP: 71.178.81.133
Old 12-24-2017, 11:48 PM
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I agree with Ed's assessment. Do you have a voltmeter or ammeter installed? if not, can you get a voltmeter on the alternator output post while the event is occurring ?
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  #4   IP: 47.156.108.48
Old 12-25-2017, 11:15 AM
JOHN COOKSON JOHN COOKSON is offline
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Quote:
Originally Posted by N29sailor View Post
Once the A4 is running and warmed up I get 2 to 3 second changes in engine sound at about 10 to 15 second intervals. The sound seems to become deeper and more 'throaty'. Any ideas?
Do RPMs vary with the changes in engine sound?

TRUE GRIT
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  #5   IP: 24.152.132.65
Old 12-25-2017, 12:24 PM
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As a test go for a short run with the belt removed, battery fully charged. Variance goes away and you'll know for sure.
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  #6   IP: 74.141.117.175
Old 12-25-2017, 04:04 PM
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Another possibility: a sticking valve. I use a cup or two of Marvel Mystery Oil per tank of gas to prevent this on my boat.
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  #7   IP: 76.7.101.46
Old 12-26-2017, 08:08 AM
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If there is no RPM change and assuming that the boat has a waterlift exhaust could this be normal as the water batches?
Dan S/V Marian Claire
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  #8   IP: 108.79.1.46
Old 12-27-2017, 06:21 PM
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maybe going thru puberty?
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