2002 Trailblazer LS weird noise

I have recently purchased a 2002 Trailblazer, and have a weird noise coming from the (motor????). I recently, just today, replaced the fan clutch, thinking this was the noise, but I still have the noise. It sounds like those honda mufflers that everyone is putting on their little cars or the fan rubbing the fan guard. It only makes this noise sometimes. Do you think I need to check my exhuast system, maybe the catalytic converter, manifold gaskets? If anyone has this noise and know what it is, please help!! :banghead:

I've seen this noise be caused by heat shields on the exhaust system. The Blazer/Trailblazers seem to be plagued with this.

Cracked exhaust manifolds or manifold studs are common on the earlier 4.2L's

Joel

Thanks for the info guys! I'm going to get those things looked at. So with the heat sheild, does it need replaced or just taken off all together? Is there a simple fix for the heat sheild?

Email sent. Check out the belt tensioner, too.

I found out the problem!!! I took it to a muffler shop here in town and the technician there said I had a blown Catalyic converter. He said the trailblazers have two, so it is best to change both of them. He said it was going to cost $416. OUCH!!! I was looking the parts up on AutoZone and O'reilly's websites, but could not find nothing about catalyic converters for Trailblazers. Does anyone know if they are called something else? This seems really high to me. Expecially just a 4 days after replacing the fan clutch for $218! If anyone knows a cheaper route, please let me know.
Thanks!

Converters are pretty high $$. That sounds like an average price for parts and labor. You pretty much have to have them to pass emissions tests. That and you have to look at a service engine soon light without them.

EDIT: I'm almost 100% positive that GM extended the warranty to 80,000 miles for the converters.

UPDATE: I finally took my TB to be fixed.......come to find out it was not the catalyic converter after all. I took it to another shop for a second opinion, and come to find out, the TB (2002) has only one catalyic converter, and the problem was a collapsed muffler. The muffler had to be special ordered because it was extremely large! Don't make the mistake I did, and let them put on a muffler for a Tahoe or Denali. I was told it would work just as well. It was much loader, and I was not pleased. I took it back and had them to order the orginal muffler. It sounds like it should now, very quiet. In all it cost alot of $$$. The Tahoe muffler cost me $75. Wich they took off and replaced it with the TB muffler, wich cost me $171.00 all together. They did not re-immburse me for the $75 muffler, and they even charged me frieght and sales tax on the other muffler. The first muffler was just a flat $75, with no sales tax. I guess they got frustrated with me because I was not satisfied with the Tahoe muffler. But anyway, I just wanted to let you all know so that you don't make the same mistake I did. Always get the orginal parts for your TB.

Good for you! Sounds like they were trying to pass off some old stock laying on the shelf.

UPDATE: ..and the problem was a collapsed muffler..

Good deal! Thanks for the follow-up. Very glad to hear you didn't fall for the 'you need both catalytic converters replaced' diagnosis. All GMT360 chassis with 4.2L have a single cat. Too bad you didn't care for the tahoe replacement muffler. Lots of trailblazer (and clone) owners pay big bucks for more exhaust noise! You can delete the huge ugly barrel sized resonator at the tailpipe end should you need to. There is minimal noise change w/out the super expensive resonator.

Joel

There is minimal noise change w/out the super expensive resonator.

Joel

You mean the super FUGLY resonator.

I removed mine and just had them put a 3" SS pipe on.

Can hardly hear any difference, it doesnt sound as tinny as it did with the resonator.


John

I did the exact same thing. That resonator is hidious. I also used a larger pipe with a very nice stainless tip, it really made the rear look better. I did notice a small sound increase though, I also noticed a small increase in torque!