My '04 Blazer has started making a "tssst" sound while in drive. At first it wasnt very bad, but now it does it about 8 times per mile.
It is coming from under the hood, and it sounds almost like an air compressor is letting out little bits of air. I really dont know how else to describe it... I dont think it's affected anything yet, but I'm worried it may do something in the long term, ya know? Anyone else have this problem? Or is it a problem at all?

Thank you,
-T

 

Is it a 4x4 ?

Zed

 

No, Vortec 4.3 V6 RWD

 

It could be a cracked or broke vacuum line , spray soapy water on all your vacuum lines and if there is a leak you should see bubbles from the soap when you rev it up and then let off , spray it generously around the throttle body too as it could be loose or take it in and have a vacuum test done on it but I do think it is vacuum related but you never know ?
Sounds stupid but have you checked your front tires for a nail or a leak , again soapy water is your friend

Zed

 

Soapy water will work for a pressure leak, but a vacuum leak will only put the soap inside your engine. To diagnose vacuum leaks, open an unlit propane torch and move it along all of your vacuum lines with the engine running. If you hear the idle increase, then you have found a leak. Carb cleaner also work well too.

Here's a thought, could it be your a/c compressor turning on and off? Try driving down the road with your HVAC system set to off and listen for it.

 

carb cleaner works great but be carfull, my buddy did it to his s10 and it started a little fire

 

That's why I prefer the unlit propane torch.

 

I appreciate it.. I will test all these theories and see what happens.. Hopefully it's somethingeasy and cheap to fix. I really dont trust myself with diagnosing it myself, so I'll probably take it in, but it never hurts to get an outside opinion before hand, maybe i wont get AS screwed...

Thanks again,
-T

 

It was the A/c compressor.. it was all jacked up. I guess it had pieces of metal inside of it from when it was breaking apart, I dont know.. luckily my warranty covered it and it doesnt TSSST anymore. Thanks for your help!

-T

 

Wow! Did you hear that .45 bullet as it went by?