i have 2 questions
q1: when i am in reverse and start to go backwards no matter how fast/slow my car makes a really loud zzzzzzz noize i know cars do make a slight zzzz noize in reverse my mine is quite loud what could this be caused from?

q2 when i sit on the spot and give my car a rev as i let off the acceleration i notice a slight shh noize as the car comes back down from the revs what could this also be

thanks heaps and i hope to get a reply soon
cheers Guy...

 

need more info..
year and modle?
auto or manual?
4 or 6 cylinder?
the more info you give us the better

 

it is a
1991
toyota camry sv21
4cylender
manual gearbox
3sfe engine
cheers..

 

Many cars have a similar problem.
I have always found bad/weak grounds in the aftermarket stereo deck installs.
A weak ground and shotty wiring will cause you speakers to make this noise, many times with the stereo off. A good way to check is disconnect the stereo or speakers from you car and see if the problems gone.

Be sure to post again if this is your problem.
I am curious and I'm sure others are as well.

 

Might be clutch release bearing also called clutch throwout bearing, when pushing clutch while stoped with engine running does noise change?