knocking rod or piston slap

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Mar 30, 2009 | 11:14 AM

hotrod351

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From: mohave valley, arizona

knocking rod or piston slap

well it seems that sometimes i have a knocking sound when driving, not all the time but some times. anyway to figure out if its a rod or piston. runs great and doesnt use any oil. hate to change the engine.

Mar 30, 2009 | 11:41 AM

Conanski

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From: Ottawa, Ontario

Put a real oil pressure gauge on it to see if it's within spec and steady, if it drops really low after warming up it's rebuild time. If the pressure comes and goes you probably have a clogged oil pickup, it's not easy to get at but clearing the restriction could save you a rebuild if this hasn't been going on too long.

Mar 30, 2009 | 11:48 AM

hotrod351

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From: mohave valley, arizona

will the oil pan clear the suspension on a 90 4X4.

Mar 30, 2009 | 02:18 PM

Conanski

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From: Ottawa, Ontario

To take it off? Yes after you jack up the motor some and drop the pump inside the pan.

Mar 30, 2009 | 02:27 PM

Opossum

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From: Renton, WA

Quote:

Originally Posted by Conanski

This isn't neccessarily true alomost all engines will have a drop in oil pressure when they warm up. This is a natural symptom of the oil thinning when it heats up. Lots of older motors will have low pressure at a hot low idle, even more so with 30 weight oil, If so put in some 40 and see if it gets better.

Piston slap and rod knock sound differant and will happen at differant times. Tell me more about what you are hearing and when. Almost no engines will develop piston slap, if you do have one of these problems it is mosy likely a rod knock.

Mar 30, 2009 | 05:51 PM

bjafeman

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This guy posted a few ways to go through noise diagnosis that might help you eliminate or identify a few things:

Engine Noise Diagnosis 101

Mar 31, 2009 | 10:25 AM

hotrod351

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From: mohave valley, arizona

im going to put a real oil pressure gauge on it. this morning it stopped doing it but the oil pressure gauge will tell me if its a loss of pressure, getting past a bearing.