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View Full Version : sounds like a slight valve rattle on start up

BWdiver
07-24-2010, 06:48 PM
It's ever so slight but there, last for a second and then its normal and quiet.
1999, 133,000 miles, great oil pressure.
I assume it has hydrolic non adjustable vales, but there should be a TQ spec.

any help would be appreciated.
retorq
07-24-2010, 09:56 PM
Vortec motors had piston slap issue, didn't they??
BWdiver
07-24-2010, 11:04 PM
Vortec motors had piston slap issue, didn't they??



It only does it on start up for a second after that no issues of any kind strong running motor and smooth.

what is piston slap and is it bad for the engine?
BakerTahoe97
10-04-2010, 11:11 AM
mine does the same thing,during the summer it didnt do it because it was warm but now that its starting to be 35 degrees outside in the morning it makes almost like a knocking noise then stops after about 2 mins, i know its piston slap but sounds like a rod knock but a rod would knock all the time once warm.Sounds bad but i just let her warm up and drive easy for the first few miles.
blueflamed03
10-04-2010, 02:49 PM
my 03 does, even warm stil has a rattle, nothing to worry about.
bowtiefreak
10-04-2010, 04:23 PM
Takes a second to pump the oil back up to the valves
raptorforme93
10-04-2010, 10:14 PM
My 1996 hoe just recently started making a "click" noise on the first start up of the day when the engine is cool.. It doesnt sound like a engine knock but more of like something hitting something. Its a sharp noise that doesnt always happen and only lasts about 10 seconds. It doesnt always happen though and today it was much colder than it has ever been this summer and it almost didnt make it at all... Any ideas?
retorq
10-05-2010, 04:26 PM
what is piston slap and is it bad for the engine?

Basically the piston shrinks enough to allow back and forth movement which you hear as the piston "slapping" the walls in the cylinder bore.

I know for a fact the LS series engines had piston slap issues, I'm not 100% sure about the Vortecs, really anything that uses a piston can develop this problem as the cylinder bore and piston wears ... some of these measurements are as tight as .0008 inches.

Bad for your engine is a relative term ... it can get so bad and there is so much movement that you will break stuff ... but I'm sure you would know something bad was going to happen long before it happened. :)