Hello, my truck went to the shop for two bad injectors but that is all takin care of now, but know my truck has piston slap is this normal.

Hello, my truck went to the shop for two bad injectors but that is all takin care of now, but know my truck has piston slap is this normal.

Does it do it when it's only cold? If I start my truck up at night time and it's really cold out, my truck does it too. Once it runs for a few minutes and gets a little warm it goes away.

if its just a little "tick tick tick" sound your talking about.. its the hydraulic lifters bleeding down.. at least thats what my research has told me.

Does your truck have many miles on it? alot LS1 style engines I've seen had piston slap somewhere around the 120K mark. This probelem never seemed to hurt anything and went away when they warmed up.

In my opinion, so called "lifter tick" on push rod engines, is very rare these days. That is because in the old days, vehicles had flat bottom lifters and the cam lobe would be the first to wear down with improper oil changes and such. When the lobe wore down, the lifter was out of adjustment after some time and that would be the tick. Todays engines have roller lifters and they are more durable. If you Do hear lifter tick on a 86 or newer vehicle, it's basically obvious the customer has not been changing the oil. Another little known fact about lifters in GM truck engines. They actually have an internal feature that will crush small particles in the oil and allow it to flow away in the oil to the filter. This was done because for YEARS GM blamed (new vehicle) lifter tick on the lifter supplier when in fact it was loose metal particles inside the engine from machining. Back on subject. Piston slap is very common and it is not a problem. The one gentleman mentioned he had piston slap or knock now after a fuel injector change. That could be because those cylinders now have higher cylinder pressure (they are working harder now cause they get proper fuel) or maybe a little piece of carbon fell into the intake when he changed the injector. Either way, piston slap is normal.

That's good info Gordon, thanks. My truck does this and I didn't notice it until about a week after I bought it and I thought it had a bad engine. I've done a fair amount of Google searching on the subject and determined it to be normal piston slap but no one's been able to say why this happens. I have about 75k miles on mine and I run synthetic oil but I don't know what oil the previous owner used.

It is due to short skirted pistons. They are as light and low drag as possible for efficiency. This also causes them to rock in their bores a little more. GM supposedly has been tweaking on the design and use of coatings to rectify the problem since it surfaced. Proper break in, keeping cylinder pressures low until warm, and maintenance are the best way's to prolong the inevitable.