Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
Hi Im David, thanks for visiting the site. please allow me some time to look up info on your vehicle, thanks
the only thing i can tell you is take a can of carb cleaner with the engine running and spray every vacuum hose, hose connection intake base, around the throttle body, maf , and see if the rpms change at any time.
well unless its a turbocharged engine that is the only thing it can be. a vacuum leak. i would suggest that if you are familiar with that technique to do it and find the leak.
when you are under load your vehicle obviously needs more air so it will take all it can get and leave your hvac a bit starving until the load is no longer required. thus making it seem like its an ac issue
if its a vacuum leak it will show up regardless of if you are driving or not. you can have someone give the vehicle rpms while at idle.
i hear ya. van are not fun to do anything on the engine......
i will find out if there are bulletins, and from experience, they dont go bad that often
check the entire pcv hose/tube
pull the throttle body, put a new gasket on it.
as long as i keep this open.
i dont think so. check the vacuum tank. check the hoses attached to it. and check the tank itself for small cracks
yep the round ball. dont worry about taking it out. have someone sitting in the van giving it gas while you listen for the origin of the hissing.
go to harbor freight and buy a stethoscope.
ill check this morninig
nothing as far as tsb's. the next thing you can do is smoke the engine. if there are any leaks they will definitively be seen.
i think, thats the only way to determine if it a leak. if the smoke test ends up being ok, there have accounts of accessory components i.e. alternator, ps pump, etc... causing similar noise under a load.
The vacuum line passes through the firewall underneath the blower motor or hvac housing down there, I have had it come disconnected there, it is very tight and I had to use a mirror to find it?
the line for the vac ball is what im talking about
Over by the accumulator there is a 3 way T for the vaccum, one is the hard line that goes to the inside, one goes to the vacuum ball and the other line which is soft goes across the front of the motor over onto the drivers side of the intake manifold just even with the throttle body, the pcv valve line comes out of it and then the vacuum source line is just underneath it. If you remove the air cleaner you can get to it.