Hello everyone. My husband has a 2001 silverado and has taken it in numerous times because of the piston slap. We went to
Piston slap is cause by excessive clearance between piston and bore and there is no fix short of a rebuild with properly sized pistons. GM has 10 or thousands of engine out there with this problem and the 5.3 is the worse it seems. Because of the amount of them and what it would cost to fix them all, GM has been saying that it is okay. You could reduce the noise but not using 5w30 oil in it and using 10w30 minimum (15w40 is it is bad) but other than that not much else you can do short of a rebuild. It will get worse with time.
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(15w40 is it is bad) ???? OK now I understand!
if it is "slapping/knock" bad because it has a thicker surface film to cushsion the extra clearance.
----------------- TheSnoMan.com
No it is caused by the shorter skirt on the new design piston. Nothing to do with bore sizing. The shorter piston skirts allows the piston to rock slightly in the bore until it heats up a bit. The "fix" is simple. Start engine and drive the truck. I haven't seen one yet that had any damage from it.
There is no particular fix, unless you want to take the engine apart and have the pistons hand fitted to each cylinder. It's an annoying noise, but I have yet to see any engine damaged because of it. And we are going on 8 years now.
Ian
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