it is bcz of the complaint in the silencer its surface may be filled with dust
Your throwout bearing is going bad.
Can be a throw out bearing in the clutch assembly going bad.
It is possible that the bearings are going bad on the water pump but you are going to have to listen to where the noise is coming from, whether it is inside the engine ( rod knock or oil pressure issues ) or outside (pump bearings or pulley issues).I lean toward internal wear or damage to the engine since the noise goes away when it warms up which indicates that when good oil circulation is present the problem goes away, bad bearings in a water pump will always make noise until they are repaired.
the a/c compressor cluth is bad. should make a grinding noise when not on and goes away when it is on.
what would cause a knockings noise in my boat 3560- 2004 transmission when in idle goes away when you give it gas
throw out bearing
Check your brakes, if could be possible that they are starting to go out on the left side.
The batter is low
loose belts
If the pitch of the noise increases with speed and also comes and goes in turns i.e. it goes away in a left turn and returns or gets louder in a right turn it is probaly a wheel bearing going bad.
i hate answers.com
why is there squeek noise when starting and then goes away when engine warms up