Got a question for everyone. I have a 2002 EXT-LT with 24000 miles. For the last year, the vehicle has had a rattle once it gets warm, at any speed, but only between 2400-2600 rpm. Above that the noise goes away. Dealer has heard the noise, then can't duplicate once it gets in the shop. VERY FRUSTRATING that they admit something is wrong, then tell me it's gone/they can't hear it/live with it. Anyone else had this before? Already had Onstar coax cable replaced, wiper motor twice, fuel tank/filler tube, O2 sensors, washer pump, brake lights...hoping not to have to get anything else done!!! Thanks!

Could it be the catlytic converter? Had a Jeep Grand Cherokee that did the same thing except it was noisy at idle. Just bought my new 03 and I hope I have better luck than you have had.

My trailblazer ext has what sounds like the exact same problem. Can't tell if its a metallic rattle or plastic - but it hits above 2500 rpm on the first and second shift - and seems worse when it is cold. Can't find it and neither can the dealer (twice). It sounds like it's right in front of the pedals - in the engine compartment directly in front of the steering wheel. Let me know if you find a solution. It's driving me nuts.

So what was the problem? I noticed my 04' does it. I am going to look over the exhaust and heat sheilds.

Unfortunately never found it. Goes away when the engine is warm. Wife primarily drives the car so I don't notice it that much. Still annoying in cold weather. Let me know what you find. I'm too annoyed at dealer mechanics who claim they can't find it.

Ya mine is also my wife's car and she doesn't seem bothered by it. I notice it when I drive it. I clamped a coolent line. I'll take it for a spin today and see how it goes.

Any possibility it could be engine knock. I have begun to notice the same thing and I have 15,000 on the engine now. I run 5-30W Mobile synthetic with a doubleguard oil filter. Just changed the oil when I noticed it this AM. And it also goes away when the engine warms up. I have been using 85 octane fuel and that may be the reason. Seems to run fine once it's warmed. Should have a tapping sound if it is the engine. As for vibrations...the engine sits on isolated mounts so vibrations are not felt inside the cab. The logical place would be the exhaust system since it routes off the engine and under the drivers side floor. Could be a loose exhaust mount/heat shield. Anyway let me know what you all find out.

I drove it yesterday and it really didn't do it. If it did it was very, very hard to hear. It only does it accelerating through 1st and 2nd gear at about 2,500 rpm and stops before 3,000 rpm. It's definetly something rattling. I clamped a coolent line that had play in it. I don't really think thats what fixed it, but it is kinda weird it didn't really make the noise after I clamped it. I noticed a few other lines touch the engine. I wonder if they would rattle enough to make the noise. Exhaust seems most logical, but mine seems to be very snug with no play. I will keep a update as drive more. Might not be all week since my wife drives it.