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Discussion Starter · #1 ·
I was driving my car down the high way and then all of the sudden i started hearing a high pitch sound coming from my engine bay. I'm thinking it may be a boost leak but i'm not positive. My mkv just hit 70,000 and i don't have an owner's manual so i'm not sure if i missed any "check ups" for my car lol. it appears to be coming from under the engine on the left side. it is extremely high pitch as if it is an alarm going off. when i turn my car off it keeps going and then slowly quiets down. it also silences every time i begin to accelerate. at first i thought my serpentine belt needed replacing but i don't think that is the case.

any opinions?
 

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Not too sure, never experienced a boost leak on these cars. Free bumps though....
 

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CEL? getting full boost? usually go into limp mode if its a big leak
 

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Judging by your description on when you hear the noise, I doubt it's a boost leak. Unless the vacuum is creating the noise and the boost alleviates it. You have a boost gauge?
 

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Discussion Starter · #6 ·
i don't have a boost gauge because i am still all stock but it did throw a CEL unfortunately. and i'm pretty sure i don't have a sai pump unless the person before me put it in. any other suggestions to what this could be?
 

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sounds like a bearing, probably a/c compressor, as it will keep spinning after the engine stops, centrifical force and the compressor clutch is only engaged with the ignition on. My compressor blew up at 40k and sent shrapnel thru the entire system and they had to replace it all, they are known to blow up on FSI, bad juju especially if you are out of warranty.

cam follower is on top of the engine, wouldn't keep going after shut down.

try turning the AC on and off and see if anything changes
 

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Your turbo continues to spin after the car is turn off and makes a high pitch noise, I would check around that area.
You do know a turbo is driven off of exhaust gases right? That means when the car turns off, the turbo stops very shortly there after...
 

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You do know a turbo is driven off of exhaust gases right? That means when the car turns off, the turbo stops very shortly there after...
Key word, "shortly there after". It does not stop instantly. I have seen turbos that continues to spin 10+ seconds after shut down. Even more so if it was revved prior to shut down. What do you think a turbo timer is used for? To cool down the oil prior to shut down; because engineers knows that a turbo continues to spin after oil flow stop and a turbo spinning after shut down with hot oil and no oil flow can cause the turbo to malfunction.
 

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Key word, "shortly there after". It does not stop instantly. I have seen turbos that continues to spin 10+ seconds after shut down. Even more so if it was revved prior to shut down. What do you think a turbo timer is used for? To cool down the oil prior to shut down; because engineers knows that a turbo continues to spin after oil flow stop and a turbo spinning after shut down with hot oil and no oil flow can cause the turbo to malfunction.
Haha. Not exactly
 

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i don't have a boost gauge because i am still all stock but it did throw a CEL unfortunately. and i'm pretty sure i don't have a sai pump unless the person before me put it in. any other suggestions to what this could be?
Yes your car has a secondary air injection. you will hear it on cold starts
 

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Key word, "shortly there after". It does not stop instantly. I have seen turbos that continues to spin 10+ seconds after shut down. Even more so if it was revved prior to shut down. What do you think a turbo timer is used for? To cool down the oil prior to shut down; because engineers knows that a turbo continues to spin after oil flow stop and a turbo spinning after shut down with hot oil and no oil flow can cause the turbo to malfunction.
those are usually aftermarket ballbearing turbos they spin for a very long time compared to the turbo that is stock in the gti kinda like this turbo rx7
 

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now i know my truck isnt a gti but it has a vacuum leak and it sounds just like a hissing sound...just saying
 

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do you guys have an sai pump? If so I'd look at that
Yes your car has a secondary air injection. you will hear it on cold starts
Its probably this

Key word, "shortly there after". It does not stop instantly. I have seen turbos that continues to spin 10+ seconds after shut down. Even more so if it was revved prior to shut down. What do you think a turbo timer is used for? To cool down the oil prior to shut down; because engineers knows that a turbo continues to spin after oil flow stop and a turbo spinning after shut down with hot oil and no oil flow can cause the turbo to malfunction.
... Just... just stop
 

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Key word, "shortly there after". It does not stop instantly. I have seen turbos that continues to spin 10+ seconds after shut down. Even more so if it was revved prior to shut down. What do you think a turbo timer is used for? To cool down the oil prior to shut down; because engineers knows that a turbo continues to spin after oil flow stop and a turbo spinning after shut down with hot oil and no oil flow can cause the turbo to malfunction.
lolz
 

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i lol at all of you
 
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