2000 Chev Silverado 1500 Noises, NEED HELP

**mammoth713** · 10-21-2010, 05:49 PM

My fathers 2000 Chev Silverado 1500 is making some really weird noises. We dont even know where to start looking for the problem..

has 145k miles on the car, well taken care of

1st Noise:
*sounds like a hydraulic line of some sort under high pressure (doesnt mean its necessarily a hydraulic line tho..) with a HISSSSSSSSS but sounding more fluid than air, if that makes sense
*This noise only seems to happen when the gas pedal is in a very precise position... say, an inch of pedal travel it starts occuring.. if you push the pedal past that point or before that point, it doesnt make the noise
*Only happens while accelerating
*If stopped, in Park or Neutral, revving the engine and/or pushing the pedal to the special position doesnt make the noise

[i'm led to believe this is a transmission issue?]

NO CLUE what it could be

2nd Noise (not sure if its related to the first one or not):
*Tonight he just started noticing this one, it makes a loud Depressurizing sound right after you shut off the engine..
*made sure the A/C was off and heat was off and tried it again... still made the noise again when shutting the engine off...
*Sounded loudest near driver's side front tire standing outside the car...

if anyone has any input, its greatly appreciated.

**IHSS** · 10-22-2010, 05:11 PM

the first one i'm not sure of but the second one might be the brake booster vacume check valve or the boosters diaphram. good luck

**mammoth713** · 10-23-2010, 02:50 PM

Originally Posted by IHSS

the first one i'm not sure of but the second one might be the brake booster vacume check valve or the boosters diaphram. good luck

yeah it almost does sound like a vacuum leak of some sort.

Thanks i will give that one a shot atleast

**bigrondownhiller** · 10-26-2010, 02:53 PM

For the 1st noise check all of the intake piping. Maybe a loose hose or something torn.

**mammoth713** · 11-06-2010, 02:36 PM

FOUND THE PROBLEM!

this one tube that runs from what appears to be the driver's side valve cover to under the plastic intake cover ontop of the intake manifold...

what could this tube possibly be? its some sort of vacuum obviously, but what is its function? it was just sitting right next to the valve cover hole it was supposed to be in.. seemed like it just plugged into the hole..

2ND of all, the transmission shifts much better now.. we thought that was an entirely different issue but turns out this vacuum has some affect on the transmission's vacuum too perhaps?

out of curiosity, if anyone could shed some light on the function of this tube, i'd like to hear it

heres a internet picture of the engine, its the tube to the right that comes out form under the plastic intake cover