I can't be sure what that sound is, but I think you are describing a typical sound of these trucks. Many of them rattle. Mine does, and others have said theirs have for the entire life of it. I don't like it, but I think it's what they do.


As for your gas, stop wasting money on high octane and additives. Your truck is designed to run on 87 no problem.

 

I would check all of the heat shields. I just tightened mine all up but I have the exact same rattle right after start up but mine goes away.

 

The ratttle is the belt tensioner guaranteed i had this problem when i first got my truck and talked to another member he showed what it was and he told me the stock tensioner are weak and a oor design search for a dayco belt tensioner buy aftermarket not stock as gm has not yet fixed the issue

 

My truck does the same thing...Has for some time as well. I would describe it more as a hum than a rattle, but it goes away. Does it when the truck is started, and when I accelerate.

Don't think it's anything to worry about.

 

same here . i have been under my truck time and time again with no luck .not any of the skid plates . at least they dont look loose.any help would be great.

 

 

There are 2 sources of the hum/rattle. Neither is major, and both are easy to fix.

First is the tensioner arm and tensioner pulley replacement. That fixes it a lot of the time, as our factory and OEM ones are not designed as well as the aftermarket.

The second is the exhaust heat shield, either on the manifold or on the down pipe where the exhaust is vertical for 6" or so after it comes off the block.

Usually there is a broken or rotted bolt/screw/thing that has come loose and lets the heat shield rattle against your pipe. On the manifold cover, tightening a couple visible bolts will usually correct it. On the pipe, you have to jury rig something.

Good luck.

 

Had the same issue, the dealer found a loose rear exhaust shield. They repaired that, but it's still making the noise. Just hope it's not anything major with the engine.

 

Ed here
I have the first gen 04 ,2.8 with 178,??? Miles. When I purchased The truck from a private ownership.it made. That ticking sound right at the start of the engine.i read on here a member said to use mobile
One,that's what I've been doing.i also read that'll it has something to do with the balancing of the cams I will have to get back with you on that one...

 

Ed here
I have the first gen 04 ,2.8 with 178,??? Miles. When I purchased The truck from a private ownership.it made. That ticking sound right at the start of the engine.i read on here a member said to use mobile
One,that's what I've been doing.i also read that'll it has something to do with the balancing of the cams I will have to get back with you on that one...

Most likely a lifter getting sticky.

 

My '04 started making the same noise a month ago. Yesterday I replaced the tensioner, pulley, and belt. The noise is gone.

 

Hey everyone! A cursory google search and here I am, I'm guessing most of you are in the same boat with something like, "Chevy Colorado rattle on startup and accelerating" Im in a 2020 Colorado ZR2 (Bison) and didn't notice it when I test drove it, but we're less than a week in and I've definitely got that rattle on start up. Not hearing anything coming from the engine though, its definitely towards the back, so I'm not too concerned with my engine. That was, until I heard a similar noise stepping on the accelerator going down the highway. Is the consensus here that its just a tensioner arm and/or heat shield and/or skid plates loose?z The bison's got front / rear / transfer case skids- I gave it a once over and didn't see any loose bolts, but I could've overlooked.