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Discussion Starter · #1 ·
The past few weeks my 2001 335xi has been making either a barely noticable high frequency whistle/squeal or a full on bombing of berlin noise (like i have a whistling turbo) from right in front of the driver seat under the hood. It only happens when the accelerator is at a certain position, especially going downhill. took it to a reputable mechanic and he said thermostat housing and gasket. this sound reasonanble? total of 550 was his price
 

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I had the same sort of thing on my 318i SE earlier this year. Turned out to be the crank case compression valve! The diaphragm inside it had split and air was whistling through the tiny little pressure release hole in the top of it (works like a kettle). Replaced for less the £20 quid, job done, hope it helps :)
 

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How do you have an 01 335xi? BMW did not start making those until 07.
 

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HiHoBrian
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The past few weeks my 2001 335xi has been making either a barely noticable high frequency whistle/squeal or a full on bombing of berlin noise (like i have a whistling turbo) from right in front of the driver seat under the hood. It only happens when the accelerator is at a certain position, especially going downhill. took it to a reputable mechanic and he said thermostat housing and gasket. this sound reasonanble? total of 550 was his price
WOW! Thermostats dont wistle,but air intake elbows usually do.
 

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I know I am new and have only posted a few times, but that is because of the "Search" function. Check it out just type in whistling and you will find all the info you need. Ask me how i know :)
 

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That's your air intake elbow whistling. If I were you I would take it to a different mechanic because he doesn't know what he's talking about. The part Itself Is about $30 and, It shouldn't take more than an hour. I replaced mine myself and It took me @ 30 min.
 

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Discussion Starter · #9 ·
thanks for info

thanks for all the info. thinking its an intake deal. its a 01 325xi by the way. sorry for misprint.
 
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