Ferocity02

iTrader: (59)

I have an '01 5.3L ECSB with 90k miles. About 3000 miles ago it developed a loud tick/tapping noise under the hood. It started abruptly one day. It only does it when the engine is cold. The tapping starts about 10 seconds after the engine starts, and diminishes after a minute or two. It varies with RPM. It is a very metallic sounding noise, almost like someone is tapping on the side of the block with a screwdriver. It's audible inside the cab and from at least 50' away outside the truck.

I've been out of the LS1 game for several years now, but I remember that this is usually caused by a collapsed lifter. Or could it just be piston slap? My LS1 had piston slap and it was no where near as loud as this. I don't see any signs of an exhaust leak. Or could this be something in the transmission? I have zero experience with automatic transmissions, only manuals.

Any thoughts would be appreciated, thanks!

sbw9056

iTrader: (9)

My piston slap started at about 70,000 miles. It sounds just as you described. I would not worry about it.

Ferocity02

iTrader: (59)

I hope it's not piston slap! This is way worse than any piston slap I've heard. I get puzzled stares every time I start my truck and someone's around.

sbw9056

iTrader: (9)

Try using a sounding rod or engine stethoscope to see if you can localize the sound.

hirdlej

iTrader: (31)

Does it go with the speed or rhythm of the crankshaft? If so, it's piston slap. If it's half the speed it's a lifter

Ferocity02

iTrader: (59)

Next time it happens I'm going to video tape it and see how fast it's tapping, and then compare that to the RPM.

MikeGyver

iTrader: (5)

When I had stock pistons (My block is iron), the piston slap was much a duller sound than when one of my lifters was destroyed. But the piston slap occurred at the same time that you hear your noise. The lifter noise never changed.

redsilv

i also have same truck 01 ecsb. had it since new, i have never heard of piston slap staying with any rpm above idle. cold starts you can hear it, but when the motor is not cold ambient temperature the "slap" diminishes quickly.
3,000 miles? change the oil and inspect for any shavings, use a magnet ifyou can. what type of weight oil are you using?
ive had my 5.3 since new and now has over 210,000 miles and i get challenges to "run it" from the duramax guys
of course they spank my ***.
what i am saying is to provide proper maintenance and "piston slap" isnt an issue. i was concerned at first but the 5.3 just wont quit
i would check for possible main or rod damage from blowing the soot out of it if the knock is as you say
damn good trucks, i just dont believe this piston slap will cause such knock
could be wrong,let us know

budhayes3

iTrader: (19)

This piston slap can and will happen even on a properly maintained vehicle, my truck does it for a few seconds on cold days. Part of how GM shaves some weight off of the rotating assembly is by using short skirt pistons, which unfortunately may rock a little in the cylinders until they heat up and expand. GM states that this is not an issue of concern and will not cause premature wear or failure or any sort.

The piston slap will also make noise throughout the RPM range, I've heard this many times on different manufacturer's engines. On some vehicles it is actually a problem, while others it is "characteristic". My old ZZx 350 had piston slap due to the centered wrist pin design, which was loud and nasty sounding when cold, but would diminish to a light tick once the engine got into operating temperature. I put over 100k on that engine without any problems though.

Now I'm curious to know what the OP finds...could be piston slap, a lifter not pumping up, or a few other mechanical issues that will produce noise that is most pronounced when cold...tough to tell without actually hearing the noise.

redsilv

got that video yet.
you got some good guys ready to give their opinion


i hope you guys help me when i get my 6.0 built