Screeching/Squealing When Accelerating

[Fabeeeen]

Hey everyone. I currently own a 2014 Passat TDI SEL with just over 72k miles. Lately it’s been making this screeching/squealing noise but only when I either floor it, or under easy acceleration, it’ll do it in 2nd & 3rd gear after 2k rpm. No issues or noises at start up or when cruising on the highway.

I’m thinking it just needs the serpentine belt replaced but not 100% sure.

 

[Tom in PT]

try spraying a "stop belt squeal" type product on the serpentine belt and see if it goes away.

 

[rocky raccoon]

Tom's plan is good but ... If it fixes the squeal, needs a new belt.

 

[Fabeeeen]

Tried spraying some “belt renew”... no go. Replaced the belt and nothing. I did see a small amount of play on the tensioner so I’m gonna replace that and the alternator pulley this weekend and see what’s up.
After that I’m out of ideas.

 

[740GLE]

you can run the car without the accessory belt, see if the noise goes away, save yourself from tossing parts at it.

 

[Fabeeeen]

I’ll have to give that a shot too.

It doesn’t do it at idle or when cruising. Only when accelerating.

 

[red4kcsq]

Boost leak?

 

[Fabeeeen]

Might be it. But where do I even look for that?

 

[Tom in PT]

I believe that if there is relative movement between the belt and the rollers/tensioner when you accelerate you should get a screech sound. Since your belt is new I think your symptoms point to either a tensioner that is too weak or one of the rollers in the accessory belt path is on its last legs. That seems more likely than a boost leak. Maybe see if you get the screech sound with the transmission in Park and you have someone rev up the engine while you stand there next to the front of the engine with the hood up looking for the source of the sound.

 

[Fabeeeen]

Well I replaced the tensioner yesterday with no luck. I had my brother in law and father in law both watching the engine as I revved it with the hood up and it would not reproduce the sound. Only when I have it more than 50% throttle it’ll make the sound. If I slowly accelerate, it’s fine.

 

[ret1614]

If you have a way to watch boost requested vs actual do so. Boost leaks can make squealing noises a lot like a belt.