GMC SIERRA VALVE NOISE

You may have a filter with a bad anti-drain valve in it. Try a new oil filter. Mike

LUBRICATION TO

Piston slap would be a much more likely cause. Bob

GM forgot how to build good quality engines. They are getting away with putting below standard engines in vehicles. There is a class action suit against them in Florida for the piston slap noise. My 2002 has the same valve noise as yours. It doesn't matter what oil you use. It would still make a rackett with 90 axle lube. They are total crap! But still the best truck on the road :)

You know what? You don't really know what you are talking about. There isn't anything wrong with the quality of the late model GM small block v-8 engines. They have been out for

5 years now, and I believe in our 30 bay dealership in a fairly large city in Canada, we have had one catastrophic failure on these engines. We don't do many repairs on them. The odd head gasket failure here, water pump gasket failure there, a few exhaust manifold bolts breaking here and there...not much really when you compare it to the failure rate of the older generation of chev small block.

As far as piston slap....better get used to it. As long as the manufacturers are attempting to balance light weight, low friction, and a lot of horsepower coupled with attempting to get better fuel mileage....piston slap is here to stay.

Ian

What kind of oil are you using?

I frequent a GenIII chevy motor ethusiast board a lot, and the resident oil experts say that synthetic oils like M1 5w30 are too thin for GenIII's. The gist of it is that the oils are "barely" 30weight.

They recommend using oils like the German made Castrol Syntec 0w30 (which is more like 40weight), or M1 0w40. There is something about the Castrol stuff here that makes it a great oil. Its the same thing that performance European cars use for their extended oil change intervals.

I know The General recommends 5w30 - and these oil-enthusiats here admit that GOOD conventional 5w30's are just fine. It's when you go to synthetics that you might run into oil consumption problems and things like that.

I can't say for sure how semi-synthics are, but maybe you want to try something different next time?

I really don't think much damage is being done. A lot of those guys run performance cams that are hard on the valvetrain and make a lot of valvetrain clatter. I had one in my 04 Chevy Silverado for a few thousand miles - I got sick of the noise and swapped in a milder street cam. Those guys run the motors HARD with the noise, and they rarely have problems.

-marc

Howcome Ford , Dodge, Toyota and Nissan V8's don't have piston slap. I would think they are also trying to lighten them up and get better mileage. I'm not saying it won't last, but who wants to listen to that rackett. At 50,000 i'm poppin mine out and boring the block and getting the pistons to fit properly. I'd rather loose a mile a gallon then sound like a piece of crap when idling.

Yup- the pistons are more like a race engine now. What's the highest mileage one you've seen so far, or do they stop coming in at 36,000 miles?

GMC Greml>

No, they still come in after the warranty period is up. I can't recall an exact mileage.....but I'm quite sure that we have had trucks in the shop with over 160,000 miles on them. This is the new style trucks, the old style trucks, we still see them in here from the mid 80's. Nobody really wants to work on them, but we do. We have a few customers to bring in their olds 70's Cadillac's, and I work on a customers 67 Malibu every now and then. Of course, the mileage on the Malibu is less then many of the 2-3 year old work trucks that come in here.

Ian

160,000 isn't bad. Call me daft, but I always thought of SBC's as 150-200,000 mile engines. Got 125,000 on my Jimmy and a new tranny, hoping more towards the 200,000 mile end of course.

GMC Greml>

I'm not sure if they're pushing their development like GM is.

I don't know of any other motor out there that responds to mods as well as these GenIII's do.

What sized motor do you have??

Lunati sells complete rotating assemblies for these motors, in the 3K range. Not sure if it's rich for your blood, but since you have it apart.... ;)

You can drop in a bigger crank in a 6.0L (4" bore), and come out with a

408. Pretty nasty.

-marc

Mines a 5.3 and 3 grand is pretty cheap for a motor they get almost that for a Mr Good Wrench engine which is a refurbished screw up from the assembly line.