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Motor Knocking

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Old 04-19-2010, 05:48 AM
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Motor Knocking

Looking for a little help. I have an 03 2500 with 117,000 miles on it. Friday night I was on a trip when I got off the interstate and when I came to a stop my truck began to knock. I shut it down and checked the fluids and everything appeared fine. I fired the truck back up and drove to my destination. I got up the next morning and drained the oil and found small metal shavings in the oil. I changed the oil and limped the truck home. The truck knocks horribly at iidle and the oil pressure drops to about 20 psi. The funny thing is put it in Nuetral it goes away, but put it in park or gear it knocks. Give it a little bit of fuel and it stops knocking and the oil pressure goes back up to normal. Any suggestions, the nuetral thing has me thrown.
Old 04-19-2010, 07:27 AM
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Flex plate broken and/or bolts loose, maybe?

It would be an easy thing to check.
Old 04-19-2010, 08:57 AM
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Your symptoms are classic big end rod bearing failure. It knocks because the rod is slapping on the crank with a bad bearing. The noise goes away at light load because the force from the weight of the piston at TDC is offset by compression and light combustion.

I'm not saying that is the problem as it needs properly diagnosed. Cut open the old filter and there may be more metal in there. If the engine gets overhauled then flush out the oil passages real good and replace or clean the piston cooling jets. They get plugged easily from metal.

If you had not said metal in the oil I would say an injector was bad but metal in the oil would not be caused by injector. Good luck with it..

Edit: I am assuming you are talking about engine oil with metal not trans oil.
Old 04-19-2010, 10:10 AM
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Thanks for the imput. It was the engine oil that had the metal shavings. Unfortunately I was on the road when I changed the oil and did not keep the filter. The new filter probably has 400 miles on it getting it home, should I pull that filter off and check it.
Old 04-19-2010, 10:47 AM
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Yep, if she is knocking and there was metal in the oil when drained, if you pulled the filter now, there should be metal again.

Sorry to hear about your bad luck.
Old 04-19-2010, 10:52 AM
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I agree with the rod bearing assessment.
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