Engine knocking

[jaslo]

I know this has been discussed before, but my 2001 Silverado has a serious engine knock, it used to do it only in the winter, now it is doing it the middle of 90 degree heat. This truck only gets driven once a week, so would synthetic oil solve this problem? Or does anybody have any good idea? I was thinking of dumping some fuel injection cleaner in it, when I have maybe 3/8 of a tank left.

[txab]

What oil are you running?

[jaslo]

I am running Valvoline 5w-30 conventional. The motor has 87,000 miles on it.

[txab]

Knocks on start-up or all the time?

 

You can try switching to a different brand. I know some have reported doing this and losing the cold start knock problem

[SILVERADOSC540]

What octane fuel?

[jaslo]

I run 87 octane and it mainly knocks only when I start the truck and engine is cold.

[SouthCo]

Is it more of a ticking than a knocking? That is common on startup and stops in less than 30 seconds. My Sierra doesn't do it but my 2003 Tahoe did.

 

 

Sent using Tapatalk

[jaslo]

Ticking or knocking, sounds like a tractor when I first start it up.

[SouthCo]

Oh if it sounds that bad I don't know. My Tahoe's tick on startup was barely noticeable.

 

 

Sent using Tapatalk

[jhm]

I know this has been discussed before, but my 2001 Silverado has a serious engine knock, it used to do it only in the winter, now it is doing it the middle of 90 degree heat. This truck only gets driven once a week, so would synthetic oil solve this problem? Or does anybody have any good idea? I was thinking of dumping some fuel injection cleaner in it, when I have maybe 3/8 of a tank left.

Same exact situation here. 2001, 101K, use to do it only in winter. Now every time I start it after it's been sitting more than 6 hours. Goes away after about 15 seconds. Has nothing to do with oil. I believe it is just the original piston slap getting worse over time. Does not affect performance or driveability so screw it.

[NitroCherokee]

My Yukon has done this since about 40,000 miles, at startup even in 90 temps it sounds like an old Cummins Diesel. I never let it warm up and am in gear usually before the starter stops spinning and it now has 194,000 plus miles on it. It's just piston slap and will not hurt anything

[Z45]

fyi................

 

Combustion Chamber Deposit Interference Effects in Late Model Vehicles

Paper Number: 940385

DOI: 10.4271/940385

 

Citation:

 

Moore, S., "Combustion Chamber Deposit Interference Effects in Late Model Vehicles," SAE Technical Paper 940385, 1994, doi:10.4271/940385.

 

 

Author(s):

Stephen M. Moore - Chevron Chemical Co.

 

 

Abstract:

 

Certain late model vehicles have experienced an audible clattering during cold engine-start that is caused by the piston top striking the cylinder head after combustion chamber deposits build up to a level that exceeds the available clearance between the piston and the head. This clattering is referred to variously as “carbon knock,” “carbon rap,” “deposit induced noise,” and “combustion chamber deposit interference (CCDI).” The audible clattering intensity increases with mileage as deposits continue to accumulate.

 

File Size: 210K

Product Status: In Stock

[Shaners]

Some Sea Foam might help clear up some the noise. I would recommend the stuff that goes in the intake and not the gasoline. GM makes their own version of Sea Foam.

[grogman45459]

Same exact situation here. 2001, 101K, use to do it only in winter. Now every time I start it after it's been sitting more than 6 hours. Goes away after about 15 seconds. Has nothing to do with oil. I believe it is just the original piston slap getting worse over time. Does not affect performance or driveability so screw it.

+1 Here with my 2001 1500 Yukon XL with 165K on the clock. Mine sounds more like a diesel as I coast down the driveway. Then it's gone after 10-15 seconds.

[chevymechanicgoodyear]

I have the same problem with my 2001 Silverado. it only knocks upon startup. the problem I found is that the oil drains to the bottom of the oil pan after it sits over night. I figured out how to fix it by switching to synthetic oil but I hate using synthetic so I just put up with the knocking noise after I got the synthetic changed out. 2001 Silverado 5.3l vortec