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2002 gmc envoy_slt
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It is pretty common especially with GM engines. A lot of manufacturers are using hypereutic pistons which are lighter and offer performance gains.
If you think your TB/Voy sounds like a diesel now, wait until you get to 95,000 miles like me! lol. It is harmless and will go away as soon as your engine warms up and the pistons expand. Engines with piston slap, providing its not from excessive wear, but were designed this way- have and will last 100's of thousands of miles just like an engine without hypereutic pistons.

Synthetic oil is a good suggestion, many use it in their Envoy/TB. I, personally use Motorcraft semi-syn 5w-30 and VSOT (Valvoline Synthetic Oil Treatment). Oils with high moly are supposed to help quiet piston slap, hence the VSOT I add to my oil. Another great forum to check out while choosing any kind of oil or fluid for your TB/Voy is Bob Is The Oil Guy website.
 

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My TB sounds like a deisel truck when I start it...anyone else have this?
Think of it as a blessing. People pay BIG bucks for them light truck diesels! Seriously though. It's just the nature of these engines on a cold startup. They'll still outlive the truck.

Joel
 

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Discussion Starter #7
I am going to bring it in, jut to get it documented, just incase something happens after my warranty is up in 10k
 

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I am going to bring it in, jut to get it documented, just incase something happens after my warranty is up in 10k

You're a clever devil! :D I would do the same thing because, with my luck, I WOULD have a problem and go to get it fixed only to hear "well gee Chris, had you brought it in before your warranty was up and had it documented, this repair would've been free!" LOL that is my luck ya know ..
 

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2002 chevy trailblazer_ltz
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I have it too, but with 114k miles it is to be expected, and I don't really care either. I think the sound gives it character.
 

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2005 gmc envoy_sle
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Hey,

That is exactly what I have, but it started recent I just notice because of the cold weather. I try searching for this problem, but nothing came up. Now I know exactly what's it call, but the only draw back is my warranty is over, but I do have extended warranty. Play the sound clip and girlfriend agree with me. Well I guess I have nothing worry about. It is a rough sound, but it does sound like a diesel engine. I could live with that.
 

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2002 gmc envoy_slt
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I have it too, but with 114k miles it is to be expected, and I don't really care either. I think the sound gives it character.
:D wow! you sure are positive about your piston slap...lol. I think most GM I6, V8 owners notice some variation of piston slap soon after 10,000 miles according to what I've read. I know when I got my 2002 Envoy it had 64,000 miles on it. My 'Voy has had some pretty loud piston slap since I bought it and motivated me to add a block heater for the cold months! The block heater certainly cut back on the cold noises. :cool:
 

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2002 chevy trailblazer_ltz
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:D wow! you sure are positive about your piston slap...lol.
I also have a 95 Eagle Talon, and that thing has had piston slap since I got it with 135k miles on it, now it's sitting at 205k miles and the Trailblazer is nowhere near as bad. If I managed to abuse the Talon for so long (redline frequently in 1st and 2nd gears) I believe that the Trailblazer will be just fine. I don't abuse the TB though, that is my new baby... Talon is just a fuel efficient toy, which still sees the red when I feel like being stupid.
 

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Discussion Starter #14
Ive made an appointment at the dealer regarding this... You all dont seem too worried, but I look at the amount of $$ i spent on this SUV, which to me is a luxury vehicle, so it shouldnt sound like a tank if I dont have a deisel....it should be quite as a kitten....id rather get it documented, and something happen down the road, and its not documented as a problem....
 

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2003 chevy trailblazer_lt
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WELL DEPENDING ON WHAT PART UR TALKIGN ABUT... CAUSE I KNOW THAT THE AIR INTAKE RESONATOR KINDA GIVES IT A SOUND LIKE A DEISEL... PART OF THE VORTEC ENGINE... UNLESS YALL TALKIGN ABOUT A DIFFERENT SOUND... VORTEC'S HAVE A LOUDER START CAUSE IT STARTS PUSHING ALL THE AIR AROUND...:m2:
 

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its common for this noise like everyone else has said..mine did it when i first got it kinda freaked me out i replaced the fan clutch n that quieted mine down but it still does it
 

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2003 chevy trailblazer_ls
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from what Ive read- the V8s are the ones that get piston slap.
the I-6 get cold carbon knock.
Running a bottle of techron- tends to quiet down the cold carbon knock for a while- then it comebacks... so the cold engine noise we all get- and a part of it can be quieted for a bit.
works for me.

http://www.pistonslap.com/tsb/010601028.pdf
 

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2002 gmc envoy_slt
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It would be nice if it was carbon knock, unfortunately its a fact the 4.2L engines use hypereutic pistons which expand with heat. The noise between carbon knock and piston slap is quite different. Piston slap sounds just like it sounds- metal slapping against metal. Kind of a sloppy diesel noise.

Carbon knock, if you've ever heard a car with it (I have a 93 Saturn which had so much carbon on the crowns of the pistons I wondered if I'd ever see metal again!) is more of a cracking, popping, sharp knocking noise.
You'd definately know the difference and aint no amount of Techron (concentrated or not) gonna fix piston slap! :D :D
 

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sorry if I made it sound like techron will cure piston slap.
but if you do have CCK- then youre getting a small knock sound when you 1st run your car in the morning. especially if its cold out.
I have had good results with quieting down this slight knock with techron.
Obviously it wont make the diesel sound go away- but it may help quiet the slight knock thats associated with the carbon buildup.
 

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Discussion Starter #20
Here is my update.

I brought the tuck in....they did hear the piston slap....but also, the serpentine belt was glazed, so they replaced that.....the truck sounds awesome...its nice and quiet....no deisel sound anymore.....
 
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