5.3 lm7 crank case noise
08-21-2014, 03:59 PM
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5.3 lm7 crank case noise Recently my friends '03 silverado started making a really loud clanking noise that sounds like its in the crank case. It doesn't really sound like a rod or spun bearing because theres alot of slop in whatever is loose. It almost sounds like the crank is hitting the windage tray. He said it started suddenly, and it changes with engine rpm, however it gets quieter so you can't hear it when driving only at idle. The gauges in the truck dont work so, I can't verify oil pressure. I checked it though, its clean and full. Has anyone seen this before or have any ideas on what it could be? I am unable to help him otherwise I would just pull the pan and see what it is. Any help is greatly appreciated.
Here is a link to the sound its making:
Here is a link to the sound its making:
Last edited by 91yj; 08-21-2014 at 04:10 PM.
08-22-2014, 10:54 AM
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08-23-2014, 05:50 PM
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Well it wasn't the flywheel or torque converter, or even anything belt driven. I used a stethoscope and it seems to be coming from inside the oil pan. My buddy is gonna pull the pan on Monday to see what it is. Will post the update when we know.
edit: Do you know of a way to check if its piston slap or sticking rings without pulling the pistons? I'm guessing check the cylinder walls for scarring right? I also found out the engine has over 200k on it, so it really could be anything.
edit: Do you know of a way to check if its piston slap or sticking rings without pulling the pistons? I'm guessing check the cylinder walls for scarring right? I also found out the engine has over 200k on it, so it really could be anything.
08-23-2014, 08:00 PM
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I believe 03 was the first year for the coated piston skirts.
I have a 2000 Silverado w/160K that sounds like a midget with a hammer in the bottom end when its cold.
I have an 06 w/87K that has a minor piston slap that is barely audible on cold start up.
After tearing several of these engines down, I usually find the loud ones have excessive Piston skirt wear from side loading and occasionally when the oil has not been changed regularly It will start to burn and gum up in the ring lands and the Pins.
Usually you will see the dark oil staining on all the internal engine parts, especially the aluminum ones.
I have had engines with 100k on them that were serviced regularly and you can hardly see any wear or staining, Then you get a similar one that was not well maintained and you will see excessive wear on the skirts, stuck rings, lots of oil seeping from gaskets and seals and sometimes even sludge in the bottom of the pan.
I have a 2000 Silverado w/160K that sounds like a midget with a hammer in the bottom end when its cold.
I have an 06 w/87K that has a minor piston slap that is barely audible on cold start up.
After tearing several of these engines down, I usually find the loud ones have excessive Piston skirt wear from side loading and occasionally when the oil has not been changed regularly It will start to burn and gum up in the ring lands and the Pins.
Usually you will see the dark oil staining on all the internal engine parts, especially the aluminum ones.
I have had engines with 100k on them that were serviced regularly and you can hardly see any wear or staining, Then you get a similar one that was not well maintained and you will see excessive wear on the skirts, stuck rings, lots of oil seeping from gaskets and seals and sometimes even sludge in the bottom of the pan.
