Q: What causes loud high pitched whistling sound ?

asked by on

My bmw is making a very loud high pitch whistling. It sounds like a siren. I took it to a mechanic and he replaced the valve cover but the noise still exists. Please tell me the problem. When I turn the car off the noise stops but when I turn it back on and drive for about 5 mins the sound comes back and it's very loud

My car has 170000 miles.
My car has an automatic transmission.

Of course it’s difficult to diagnose a noise without listening to it, but it sounds like you’re engine is trying to pull air through a passage that is not quite closing up. When the last mechanic replaced the valve cover, he was probably suspecting there was a restriction in the crankcase ventilation at the top of the cover. With a high pitched noise it can be difficult to get a fix on the direction that it comes from but here is a trick: get a piece of plastic or rubber hose about two or three feet long and put one end in your ear. If you wave the other end around, you’ll find that that it becomes a very directional kind of stethoscope, enabling you to pinpoint the origin of the sound easily. It will probably be a collapsed hose somewhere in the intake system, but it could even be something as simple as a loose gas cap. If you contact Your Mechanic they will send a technician to your home or office who can locate your noise and explain what you need to do to fix it..

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. What causes loud high pitched whistling sound ?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Rough idle when in drive..but idle is fine when in nuetral or park

Hi there. Check for vacuum leaks on the engine. A small leak will cause the engine to stumble when the rpm's are low, like in gear on automatic transmissions. Look around the intake manifold for the gaskets being broken. Check...

Q: Jeep Wrangler no crank no start

Hi there: There are some very rare instances where an ABS sensor failure will trigger an OBD-II error code that disables the ignition timing system until it's repaired. However, more times than not, a no starting issue is caused by...

Q: Thick white smoke coming out of tailpipe

Hi there. White smoke is an indicator that coolant is getting into the combustion chamber and exiting out the tail pipe. When you overheated the engine, the cylinder head gaskets blew and the head or block might have cracked from...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...