More than likely you have a vacuum leak at one of more vacuum hose connections. Start the engine and spray all the connections with WD40. The instant you find the leak the engine RPMs will change. You can also use Starter Fluid but I hesitate to recommend it due to the volatility and possible chance of an explosion. WD40 is much safer to use.
Madagascan hissing cockroaches make a noise by forcing air out of a special hole.
when you breath is air and force it out with your tongue it makes the hissing noise
Vacuum hose leaking.
i have heard that noise and I believe it is coming from the body frame connection and i also heard that u can get a kit to eliminate the noise. Ed
Noise coming from engine in Oldsmobile Cutlass could be as a result of an oil leak in the rear of your engine. This makes the gears to wear off leading to severe knocking noise.
Some systems use engine vacuum to move the control doors. You could have a vacuum leak.
Flex plate (you might know it as the fly wheel) rubbing on something? Bad alternator? Trace the sound to where it's coming from, describe and ask again.
making a hissing noise
FORDS ARE A poc
The hissing may be due to a disconnected vacuum line. Look for a loose vacuum hose and/or a tube on/near the throttle where it might connect to.
if you are getting a hissing noise when you press the accelarator , it might be coming from the exhaust , this is usally caused by a clogged catilytic converter
A radiator is a device found in the engine of vehicles that cools the engine by circulating air. A good sentence would be, the radiator in my truck is making a hissing noise.