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"Hollow" rattling sound in engine
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famvburg
New User
Feb 27, 2011, 4:56 PM
Post #1 of 4
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"Hollow" rattling sound in engine
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Hey y'all, my first post here. I have an '88 Dodge Dakota w/ 3.9 V-6 & has just under 60K original miles. I have come up with a rattling sound I can't pinpoint. It's kind of a hollow sound, like a rock rattling around in a bucket. It sounds like it could be coming from under one, or maybe both valve covers. It also sounds like it could be at the front of the engine. All of the pulleys are tight. The harmonic balancer has a bit of wobble to it when running, but it's tight. The engine basically runs smooth at idle but when sitting still & I rev it up, it does have some uneven running, almost like surging, I'd say about half throttle & higher. I can't say I notice that when driving tho. I'm wondering if it could be a lifter or something loose under the valve cover(s). It doesn't sound like a stuck valve & as I said, it idles relatively smooth. I can't say it sounds like a rod knocking & technically, I guess it shouldn't be. The rattle does change with RPM. It also isn't 100% of the time, it will go away & varies in intensity as well. It doesn't seem to be smoking or blowing oil, tho it does have a few leaks. So, before I start pulling valve covers, anyone here have any suggestions? Thanks.
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 27, 2011, 5:00 PM
Post #2 of 4
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Re: "Hollow" rattling sound in engine
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I'll bet everything that you have a bad harmonic balancer. The fact that is wobbles tells you that the rubber has separated so the center hub is not connected to the outer pulleys any more. Put a chalk line from the center, out to the edge and run the engine and see if the mark is still aligned.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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famvburg
New User
Feb 28, 2011, 7:22 AM
Post #3 of 4
(4274 views)
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Re: "Hollow" rattling sound in engine
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The mark isn't aligned. Would the bad balancer cause that hollow rattling sound? The sound does sound a bit like a pulley rattling. My only past experience with balancers has been on a Mack truck & it was just a bad vibration after having some work done 'cause somebody (not me) had dropped the balancer when they removed it! Thanks.
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 28, 2011, 7:27 AM
Post #4 of 4
(4271 views)
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Re: "Hollow" rattling sound in engine
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Yes, it certainly would. If the mark no longer lines up, you have proven beyond a doubt that the balancer is broken.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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