Diagnosing 2008 GM 5.3 startup noise

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I have a Chevy 5.3 in a 2008 Suburban with 118K miles. Current oil fill is Mobil 1 0W-30 with a Wix filter. Morning temps have been in the lower 30s the last couple of weeks. Again today, I had a prominent tick or slap at startup. I was thinking (hoping) it was a pulley but the stethoscope told me it was coming from under the valve cover on the driver's side near the front. It lasted several minutes before I pulled out of the driveway. I stopped and got out about 1.5 miles away from home and it was gone. I've had this happen from time to time since I bought the vehicle last January. I didn't notice it in the summer months at all. But for the oil I'm using, there should be any flow problems when the temps are right at 32. Also, I've checked the oil filters I've pulled off it and there's no unusual debris or gunk. A little varnish that was on the dipstick when I bought it has been cleaned up for several months now. So there shouldn't be junk in there clogging passages. FWIW, I park uphill in the driveway but oil pressure gauge reads fine.

Any ideas what I'm hearing and why? Thanks.
 
Piston Slap. Common in the LS engines. I have it in mine and so does my buddies. Just something you need to get used to..wont affect the lifespan. I have used 5w30, 10w30, 5w40 and 15w40..nothing seems to make a difference. Just a design flaw.
 
This has AFM/DOD, right? You can use a device like a "Range AFM Disable" or get a custom tune. You will not lose fuel economy, and it's better for the engine long term. Not sure if it will help your startup noise but at least you can get rod of the AFM garbage.
 
If its a "bright" tick or click, its just a lifter that drained down. If its a deeper "rap" somewhat like a diesel, then its piston slap. Neither one is harmful, neither one is worth doing ANYTHING about. There was a big kerfluffle over the Gen-IV GM v8s came out and had prominent piston slap (the engines commonly and generally referred to as the LSx engines, even if its really an LQ). Its not a problem with the LSx engine, its a problem with all the engines that came before it. The older engines had offset piston pins and tall piston skirts that minimized piston slap by "pre-loading" the piston thrust face, but the downside was a bit more power wasted on friction. Quiet, but wasteful. Most modern engines have very short skirted, lightweight pistons with centered pins to minimize friction and maximize power, the cost being a little more noise due to piston slap.
 
Here's a wild guess--check to see if any of your exhaust manifold bolt heads are broken off. It could be an exhaust leak. (I learned that's a common problem from ls1mike last summer.)

My 2001 5.3 started to knock slightly for the first few minutes after a cold start last year, whenever temperatures were in the 40s or below. Oil was Mobil 1 5-30, 115,000 current miles. I figured piston slap was finally catching up with me and would let it run an extra minute or so before driving.

In June I found a broken front exhaust manifold bolt, thanks to Mike, and installed a clamp to tighten the manifold back down. We've had a few cool mornings this week, and the truck hasn't knocked yet. Tomorrow morning is supposed to be in the 40s, so that should be the test.
 
Thanks, everyone. Great info. and it sounds like nothing to get too bothered by.

Yep, it has the AFM feature. And I'll check manifold bolts.

440Magnum, I'd label it more tick or click than a diesel-like rap. Based on your info., I'd lean more towards this being a lifter issue.
 
My 2009 with about 138,000 on it lifter clacks and piston slaps for the first few seconds of startup. I hate it but once it has a little temp in it the piston slap goes away. The lifters only tick for a few seconds.
BTW, I run 5-30 Mobil 1 and a Baldwin oil filter.
 
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