Mine sounded like a diesel also. Just awful. Took it in to the dealershop and it was narrowed down to a leaking exhaust manifold. They replaced it for 180 bucks and now it starts and runs very quiet. A big difference.
I've got the same problem with my 02' I-6 Bravada.
Now that summer is here (NJ) the sound is gone within 1 to 2 minutes.
I don't hear any unwanted noises after the first start of that day until
the next cold start of the following day. Def a lot noisier in the winter months.
Sucks but I keep in mind that I've got 130K and she's still running strong.
I just bought a 2005 Trailblazer with the 4.2 and it sounds like a diesel. I was worried until I read y'all's post. It's a great vehicle. I added some Greased Lighting oil additive and it helped. Quiets down after it warms up.
So called diesel sound like is the nature of this Beast. I wouldn't worry about it , disappears after warm up. However personally I'm strongly against using any oil additives to quiet it down. Many of the additives can change viscosity of the oil and that may cause a problem with VVT. As long as you use good quality full synthetic 5 W 30 oil like mobile one you should be fine. It does have outstanding lubrication during a cold start. Don't forget that most of the engine's wear occurs during a startup , so quick oil flow is very important. Some people putting a 10 W 30 oil to quiet the noise but not me. I prefer to stick with 5w 30 good quality synthetic oil for better fuel economy , less wear on the engine and quickly warm up. That's just my five cents
Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum
A forum community dedicated to Chevy Trailblazer and GMC Envoy owners and enthusiasts. Come join the discussion about performance, modifications, troubleshooting, towing capacity, maintenance, and more!