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2003 chevy trailblazer_lt_ext
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14 Posts
Discussion Starter · #1 ·
I experience a very loud hissing noise when under load or passing it starts at a about 3000 rpm's. The other day I was following my wife and she passed a car while I followed behind her and it sounded like a jet engine really loud. I have no codes and if I drive slow and do not accelerate fast it is not there.:weird:
 

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2002 gmc envoy_slt
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3,203 Posts
Just with the description of "Jet Engine", have you checked the fan clutch....that's usually the source of a sound like that. When they start to fail, you'll get the sound after startup until the motor revs over 2,500-3,000 and the fluid returns from the high-speed area of the clutch. When they're about shot, the noise/affect will remain during driving and not turn off. (Eventually this *should* turn on the CEL and set a code, but only once the actual fan speed varies from the commanded speed by a specific amount or percentage).
 
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