yeah i think all these trucks make noise.. every now a then ill park it an dleave it running and ill slightly hear a lifter tap tap tap tap tap! it drives me crazy!

 

your hissing noise might be the seal in you brake booster if you hear in the driver side. If you have 03 or 04 check the seal between the booster and the little vacuum reserve tank they have. if its bad you will hear it at idle and when truck is turn off.


2004 Chevy LS
RC/SB
LM7 5.3L
4l65E w/SHIFTKIT,SERVO
G80 w/3.73

ADD ons: LS1 electric Fans,TB bypass, TB spacer, 160* Thermostast, K&N Cold air induction, Borla ProXcess Muffler w/Turndows, NitrousWorks 150 shot, HP Tuners Tune, 295/50r16 BF GOODRICH radials.

Future Mods 6.0L, patriot 5.3L Stage 2 head and cam kit, Vigilante stall, 4.10 gears Longtubes and OFY pipe, TNT N2O set up.

AGGRESSIVE MOTORSPORTS live life at full throttle......

 

Maybe it is just a high pressure line. Theres nothing wrong with the truck. It runs great....just has that little noise. Thanks for all the opinions. Ill check the lines and seals tomorrow.

 

Mine has been doing the same thing since my Pacesetter install. I will tighten all of the bolts down from the center outward and it will fix the problem for a day or so and then it will come back until I retighten them. I think I'm gonna try to get some new factory gaskets and see if it helps out any.

 

How many much do you torque the manifold bolts?

 

Not sure, I just torqued them down pretty tight.

 

25 lbs use factory gaskets.

 

Are factory gaskets better than Fel Pro or other good aftermarket ones?

 

i have that same problem, except mine is more of a whine than a hiss, any input?

 

Yeah, factory should be the best out there.