Do all vortec engines knock eventually?

[DJJ]

After reading so much about the vortec piston slap problem I'm getting curious. Does anyone have a high mileage vortec (4.8, 5.3, 6.0) with no knocking problems?

 

Doug

[HillHound]

What mileage is the knocking supposed to start at?  Mine has a 5.3 with 16800 miles and so far I've had no problems with it.  Most (but not all) of the knocking problems I've heard of so far seem to be associated with the 6.0.  

[GreenRado]

DJJ,

 

My '99 5.3 has 43K miles now and no knocking at all.  Occasionally I get a minor "ticking" noise, but you can only barely make it out when the truck is along side a wall, for example.  HIllhound is right, most of the serious cold start knock is with the 6.0L, but it is not un-heard of in the 4.8/5.3 either.  I don't know your history, but to hear the F**d and D**ge guys talk, all Vortecs have this issue, and I believe it is a very small minority that actually do.  Let's face it if what the competition is saying is really true, then I don't think GM would continue to outsell Ford, and the Silverado would not be gaining market share against the F-150!

 

We are getting hints from GM that they have major redesigns for at least 1 variant on the 5.3L, an all aluminum that will go into the extended versions of the Envoy/Trailblazer and the new SSR.  I am hoping these will trickle down to all the Vortec V8s for the '03 model year.  You can read about these in the GM News here on this site.

 

BTW, welcome to the forum and site!

[BigBlackMotor]

No, not all of them knock and the ones that do knock don't typically knock on more than 1 or 2 cylinders.  It is a manufacturing consistency problem.  The new piston designs make the allowable piston to cylinder bore clearance much more critical and GM has yet to figure out how to hit within tolerance consistantly.  Piston slap is not a new problem.  It recently got notariety in 1999 Ford (I don't remember the engine size) and they promptly replaced entire engine assemblies.  Daimler Chrysler had some and treated them the same way by offering to replace engine assemblies. GM's latest round first gained notariety on the 6.0 with a TSB they released in fall of 2000.  Other TSBs on other engines have followed since then.  The piston slap defect now exists on 1999-2002 3.1 , 3.4, 4.8, 5.3, 5.7 (LS1), and 6.0 per TSBs from GM themselves.  I have an 8.1 and have heard others that slap badly and use undue amounts of oil although no TSB exists on the Big Blocks yet.  For more information on GM's great Piston slap problem, see http://www.gmpistonslap.cjb.net

[HillHound]

After reading so much about the vortec piston slap problem I'm getting curious. Does anyone have a high mileage vortec (4.8, 5.3, 6.0) with no knocking problems?

 

Doug

Why are you asking?  Do you own a GM truck with a Vortec engine and if so what do you have?

[DJJ]

Yes, I have a 2002 Silverado Reg Cab Sport Side with the 5.3L engine. It only has 5k miles and has had no problems.

 

Thanks for the responses.

 

Doug