High-pitched whistle w/ acceleration

[Bongo]

So this is a pretty old thread but I figured I'd just toss this in here. Finally got around to changing out my clutch throwout bearing. I haven't touched anything to do with vacuum lines aside from smoking it to find not one single leak... not one single leak at all. When I drove the car to work, the whistle was still there. Changed the bearing, drove home, the whistle is gone completely. Been driving it for roughly 3 weeks since replacing the bearing...whistle still not present. The whistle sound was coming from my throwout bearing 100% all day.

Anyone that has any knowledge about mechanics knows that a very slight polished metal to polished metal contact can in FACT cause a whistle sound. I've personally run into it before and will certainly run into it again.

Also the whistle can be pinpointed on a lift without taking anything apart. This is done by putting the car on a lift, having someone sit in the car with it on in gear, neutral, in gear with clutch in, in neutral with clutch in, out etc. Then another person underneath the car(me) holds a mechanics stethascope(basic dr.s stethascope but with a point on the end if you don't know) on different spots around the trans housing while the person in the car accelerates slowly, or pushes the clutch in in gear, out of gear etc. to create the sound. If the sound gets louder the closer you get to where the bearing would be then that indicates it's coming from the bearing..... It's really not a hard thing to do at all... it's kinda basic mechanics honestly... and anyone that doesn't know that a whistle sound isn't 100% a vac leak....well shouldn't be working on cars in the first place....

So yes, the whistle sound that you are experiencing can most certainly be caused by your clutch throwout bearing. Again...OP I hope this helps if you're problem has not already been solved.

[TheFunk]

For educational purposes I will add that I did find the source of the sound. I thought I had ruled out the filter itself but somehow i was wrong on that.
Ended up just being the sound made by that intake filter under certain loads.

Ran a cheaper cone filter for a while with no whistle, then I threw the stock airbox back on for a while with no whistle. One day out of pure boredum I went back to my original setup and now that I know the sound is harmless, I've grown to actually enjoy hearing it when I accelerate.

[ninjawagon]

Interesting you have pinpointed the throwout bearing on a lift as the source for the noise you are having.


Mind elaborating on how exactly you did that? You know, without actually looking at the input shaft or taking anything apart at all, its interesting you can pinpoint the throwout bearing.


And, seriously, if anyone is confusing a throw out bearing with a vac leak, they shouldn't be working on cars.


If the throw out bearing is at fault, simply engaging/releasing the clutch will provoke changes in the sounds its making. It will have nothing to do with load. The OP would be able to provoke the same sounds without the car moving.



On the other hand, that intake screams vac leak x 100.


Step on the gas = greater pressure in the intake, pulls the leak shut. Lets off the gas, vac goes away=no more sound.


Feathering the peddle just right to get it to happen = creating the perfect scenario for vac pressure to actually provoke the leak to whistle.


Can you whistle?


Isn't there a limit to how loud you can whistle? At some point, doesnt too much air pressure in your mouth defeat the actual whislting process?

ok.


Just checking.


Bearing, whats that do? What does the throw out bearing have to do with this issue? Welp, if it was bad, it would make whiney grindey noises at all sorts of RPM's and it would sound different with the car in gear vs not in gear. You would be able to provoke the sound with the clutch pedal, not the gas. The throw out bearing is basically functioning when the clutch is depressed.


Now, the input shaft bearing, yeah, that can provoke some grinding noises under load at a given RPM. I am pretty sure the OP would notice the difference, and if not(no offense op), the op shouldn't be working on cars.

I mean, air movement, whistle sounds vs grinding bearing going out? Yeah, pretty sure that sounds very different. Throwout bearings show their symptoms when you engage/release the clutch.


Bearing applies pressure against the pressure plate to seperate contact between the clutch and pressure plate. The throw out bearing specifically is not relevant to load specific operation(in gear, driving down the road)

Agreed! Bearings don't car what kind of load is on them. if they are bad they are bad and only get worse and eventually make a supercharger type noise and then cease. I noticed in the video that you have this noise at specific RPM range and load. Which supports more of the vac leak points that were made in the is quote above. specific eninge rpms need "x" amounts of air for the engine to complete proper combustion, that air moves at a certain speed(vacuum) and if there is a leak at certain air flow rates air will find other means of getting into the engine. Thus increasing the possibility that a vac leak is a very very good culprit.