Knock

[jaslo]

On my 01 pickup, I have the knock when cold. Was wondering has anyone tried using a different brand of oil or type to make the knock go away and has it helped? Thanks

[ken1mod]

Thicker oils can quiet things down. as long as the noise is gone in 30 seconds or so, it is not a problem. my 5.3 with 125k on it is a bit noisey on ice cold start but gets quiet quickly. I use 10 30 walmart syn oil.

 

Ken

[VMax2007]

On my 01 pickup, I have the knock when cold. Was wondering has anyone tried using a different brand of oil or type to make the knock go away and has it helped? Thanks

 

Oil brand/type will make little to no difference. This is known on these engines as "Piston Slap" and is due to the short skirt design of the piston. Once the piston warms up and expands, the noise stops. This is common to some extent among almost all 5.3 and 6.0 engines from 1999-2003 or so? It is an annoyance but has not shown to be a problem as these motors run 200K+ miles with this symptom. There is info on this all over the forums and GM sites.

[ken1mod]

doesn't a thicker oil provide more "cushioning"?

 

Ken

[codyssilveradoz71]

GM engines are known for this knock noise when its cold. My car engine does it, and I asked about the knock noise and I was told that GM motors are known for having these. There is no way of getting rid of it. Thats what i heard, the knock is not a bad thing, it just does it when engine it cold, and goes away when engine warms up.

[VMax2007]

GM engines are known for this knock noise when its cold. My car engine does it, and I asked about the knock noise and I was told that GM motors are known for having these. There is no way of getting rid of it. Thats what i heard, the knock is not a bad thing, it just does it when engine it cold, and goes away when engine warms up.

 

This is the first I have heard of it in a car engine. I thought it was just the 5.3 and 6.0's from 1999 until recently. Interesting.

[wynton]

I had a Trans Am with an LS1 and it did it for about 2 minutes no matter how cold it was outside.

[codyssilveradoz71]

yea, my car makes the cold knock noise for a couple minutes or so and then fades away as the motor warms up. My 3.1 does it everytime I start my car, and it cold knocks, but fades away as motor warms up.

[VMax2007]

yea, my car makes the cold knock noise for a couple minutes or so and then fades away as the motor warms up. My 3.1 does it everytime I start my car, and it cold knocks, but fades away as motor warms up.

 

I am wondering if these car examples are the same thing (Piston Slap) or if they are Hyd Lifter related?

[jaslo]

Well my truck is a 4.8 v-8. But I guess that doesn't matter anyway. It used to not do this until it had about 80,000 miles on it and then it started.