Re: 5.3 LS Top End Noise
 

Seems to me with a quarter million miles on it, the expeditious thing to do would be to replace the cam,lifters,pushrods and rocker arms. If one or two parts are worn beyond the valve train's ability to compensate for itself, the rest can't be too far behind. I'm sure that engine would have a steel roller camshaft as well. It probably wouldn't go flat and put shrapnel throughout everything, it probably would just wear down smoothly,but that and a new timing chain and gear set would probably set you right up.Who do you suppose has the record for the most miles on an original engine?

Re: 5.3 LS Top End Noise
 

If this is an 07 model new body style, it could very well be a lifter problem. If it is an 07 it should have active fuel management which disables 4 cylinders to supposedly decrease fuel consumption. These lifters are prone to failing and causing problems. Eventually, it will result in camshaft wear. If it is not a new body style 07, then it would more than likely be a lifter issue. If the noise is mainly when it's cold, it is very likely that a lifter is just getting weak and it bleeds down when sitting.

Re: 5.3 LS Top End Noise
 

It's the Classic body style. Lots of chassis parts on this thing like calipers and hubs are 06'pieces. No AFM. There is another Classic body style truck on this job site, an 02'with 297K on it. The truck has been good to me. Still have the original exhaust, starter, alternator, and trans.

Re: 5.3 LS Top End Noise
 

Had that same noise on my '01 Suburban with the 5.3. Had a leaking head gasket as well so while heads were off I replaced all 16 lifters. That was 5 or years ago at around 185k give or take. Now at 222k noise has never returned.

Re: 5.3 LS Top End Noise
 

For whatever it's worth Melling lists 2 pumps for that engine M295 and M295HV. The HV pump flows 18% more oil and is recommended for high mileage vehicles to quiet valve train noise. Might try that before you tear into doing lifters etc not saying it will solve your problems but a lot easier than pulling the intake etc---Fed 387

Re: 5.3 LS Top End Noise
 

Are you sure it isn't an exhaust leak ? These motors are known to for the manifold bolts to break of mostly on the very back . I had this same problem chased it lifters , flushed , different oils turns out that is what it is they even make a kit to fix the problem I found through a buddy of mine that had the same problem I will try and find the

linkhttp://kralautoparts.com/product/exhaust-manifold-bolt-repair-kit-kap169

Re: 5.3 LS Top End Noise
 

Will look into the exhaust leak potential. Haven't heard the noise in a couple days, which is a good thing, unless you are trying to find out more about the problem. I'm trying to look at all the possible causes for this before I do anything too involved. Thanks for all the input guys.

Re: 5.3 LS Top End Noise
 

Brian, Take a look at Dorman #917-107 & #917-142 exhaust manifold clamps, they do work.John Kissel

Re: 5.3 LS Top End Noise
 

Have same issue with my 94 Caprice wagon with a 240,000 mile LT1.
Idles smooth as glass in gear but stumbly in Neutral.

Replaced parts and went through every electrical and fuel system.
Between 3000 and 4500 rpm pulls but there are funny sounds.
Feels and sounds like rocker/valve noise.
Pulling the Valve covers ..nothing!

Rebuilt LT1 being prepared by Rockville Ring & Bearing.
Upgrading to a PerformaBuilt HD 4L60E OTW !
If this one does not live time for a 6L80E.

Dan

Re: 5.3 LS Top End Noise
 

Check all the ex manifold bolts #7/8 are usually the culprit.We've done some of the HV oil pumps and they do work.Have seen a ton of bad lifters/rockers.(Noise is most noticeable on cold starts.)
former GM tech...good luck

Marty