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2002 chevy trailblazer_lt
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16 Posts
Discussion Starter #1
hey all!
This is my first time posting as I am a new member. I have a few issues maybe you can help!
I have a 2002 trailblazer LS with 4 wheel drive and an automatic.
-At aprox. 45mph and 61mph I hear a mechanical rattling sound coming from under the truck right around the drivers seat. I have no other issues; change the oil like religion and generally treat the vehicle better than I treat myself. It has 112,000 miles on it and I realy havent had any issues with it.
Back maybe 40,000 miles ago the transmision would seemingly slip into nuetral leaving dead in the water. I would pull it to teh side of the road and let it sit in park for a few minutes and it would work fine. The dealership repalced something like a shifting solenoid or module; luckily the $1200 bill was covered under my warranty, maybe its going bad again. I cant find anything rattling and there is no sigh that anything is wrong; I kinda concerned its leading up to something major.

-last but not least my fan sounds like jet engine taking off; after reading other posts it seems its most likely the fan clutch. It happens a few times a week for a couple minutes, should I worry?

Thanks in advance for the help
 

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Registered
2002 chevy
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2,582 Posts
hey all!
This is my first time posting as I am a new member. I have a few issues maybe you can help!
I have a 2002 trailblazer LS with 4 wheel drive and an automatic.
-At aprox. 45mph and 61mph I hear a mechanical rattling sound coming from under the truck right around the drivers seat. I have no other issues; change the oil like religion and generally treat the vehicle better than I treat myself. It has 112,000 miles on it and I realy havent had any issues with it.
Back maybe 40,000 miles ago the transmision would seemingly slip into nuetral leaving dead in the water. I would pull it to teh side of the road and let it sit in park for a few minutes and it would work fine. The dealership repalced something like a shifting solenoid or module; luckily the $1200 bill was covered under my warranty, maybe its going bad again. I cant find anything rattling and there is no sigh that anything is wrong; I kinda concerned its leading up to something major.

-last but not least my fan sounds like jet engine taking off; after reading other posts it seems its most likely the fan clutch. It happens a few times a week for a couple minutes, should I worry?

Thanks in advance for the help

Could be the transmission solenoid stuck on On, which leaves you into limp mode. I have the same problem as well.

do you have any modifications done lately?
 

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2002 chevy trailblazer_lt
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16 Posts
Discussion Starter #3
No new mods. RPM's don't drop either. If it helps it happens accelerating and decelerating every time I hit that "sweet" spot. I also don't have any idiot lights coming on. The truck runs great just that little bit of racket. I really wouldn't worry about but I drive 30 miles to work 5 days a week and I don't want to get stranded.
I think I'll crawl underneath it this weekend to investigate again, maybe I missed something. Until then i'll just keep truckin!

Thanks for the advice
 

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2002 chevy trailblazer_lt
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122 Posts
Kinda sounds like someone's shaking a coffee can full of pennies?? Been searchin for the source of that one for 40K miles.
 

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2002 chevy trailblazer_lt
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16 Posts
Discussion Starter #5
Yep! At least I am not alone.
I forgot to mention that if I stay steady on the gas the sound wont stop.
I work on some variable frequency drives at work that at a certain speed make things vibrate and electrical equipment act up; maybe its something similar.
 

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2003 gmc envoy_slt
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7,190 Posts
:tiphat Welcome :tiphat The fan clutch does sound like it is on it's way out. Just start saving for a new one. They generally don't go out in a catastrophic manner. Even when completely locked-up they will not strand you. A lot of noise, lower MPG's, and reduced power. But it should get you to your destination.:m2:
 

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2003 chevy trailblazer_lt
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49 Posts
Is it on the drivers side or passenger side? Are you sure its on the drivers side? Reason why I ask is because recently I had the same description and it was the heat shield over the catalytic converter/exhaust pipe, and it would go away when you hit the throttle, but at a steady speed or at a stop it would rattle like crazy. I would up buying big fender washers and some new nuts and "bolting" it back onto the existing studs, as the shield is aluminum and it corroded around the studs.
 

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2005 chevy trailblazer_ls
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1,733 Posts
:tiphatHello and welcome to the site! VFDs? sounds like a mechanical (sheet metal) worker, or sparky. I agree it may be the cat shield hopefully as that will be the cheap, easy fix. Good luck either way and I'm sure someone on here will be able to help you.:tiphat
 

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Northwest Chapter
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11,824 Posts
If the rattle only happens at a certain RPM/speed then its most likely a clearance issue where the engine is vibrating towards a different place than normal so you get interference and the noise. Get under the TB and tighten up the cat heat shield, its known to work itself loose over time.

For the fan clutch, as long as the noise goes away after a minute of driving its ok. Mine is the stock one from 02 (I know, its almost a miracle in iteself I havent had to replace it!) and its loud on cold starts for a minute then quiets down and is fine.
 

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2002 chevy trailblazer_lt
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Discussion Starter #11
The rattling sound seems to be coming from the drivers side, but we all know how sound can travel and throw ya off. The heat shield idea seems like a likely suspect, I'll check that out first.

My fan clutch is also original, as is most of the truck. It amazes me that you can find sites that blast these vehicles; I have been very happy with mine.

I'll keep everyone posted as to what I find
 

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2002 chevy trailblazer_lt
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16 Posts
Discussion Starter #12
Well I finally got under the trailblazer; sure enough the very back heat shield nut had pulled through, a washer latter and i am back in business.
I took it for a test drive and found the rattle happens but at a different speed and it is no where near as loud. Without a doubt I have another loose nut.

Thanks everyone for there help
 
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