5.3 vortec knocking when cold

[lee2690]

I just got a 1999 chevy silverado pickup with a 5.3 vortec engine. When I start it up it has a slight knocking noise until it warms up. I was told by a number of people that it is normal. I was wondering if anyone was experiencing the same things.

[Flatrater]

Dude its called piston slap happens when engine is cold the sides of the piston slap the cylinder walls The offical word from GM is that it is normal!

[lee2690]

Thanks for the imput it is just a little scary when you spend so much money on a pickup and the dammed thing knocks.

[99' Z-28]

Dude its called piston slap happens when engine is cold the sides of the piston slap the cylinder walls The offical word from GM is that it is normal!

Thanks alot dude, how are you so sure that is the problem?

[herbs]

if it sounds like lifters, there is a service bulletin out, i don't know the number i can find if you want i think. according to gm there is no repair nor harm done.

[lee2690]

If you could find that number and let me know where I can find out the information I need, that would be great.

[Northkat11]

I've got the same year and engine Silverado.

A couple of things to check.

First, what type of oil are you using? 5W-30 or 10W-30 will make a difference. USe only 5W-30 and quality of oil makes a substantial difference as well.

If it is knocking now, then add a container of Rislone oil engine treatment. In 1 start the knock went away and never has returned ( mine definitely sounded like a lifter).

Change oil really regular... you don't want that investment to disappear by trying to sqeeze an extra 1000 K out of an oil change.

[1991FZR600]

Originally Posted by lee2690

I just got a 1999 chevy silverado pickup with a 5.3 vortec engine. When I start it up it has a slight knocking noise until it warms up. I was told by a number of people that it is normal. I was wondering if anyone was experiencing the same things.

They fixed the knock in 2003.