vacuum leak

[JWerner2]

2000 LS V8.


As I was topping off oil and tinkering around under the hood yesterday I noticed a very high pitched whistle coming from behind the TB area.


I flipped the throttle open and the sound got higher pitched and louder then as the RPMs went down back to normal Idle the sound got a bit quieter as it was when I noticed it.

Could it be a hole in a hose? What hose would it most likely be coming from in that area?

No codes but I smelled a slight odor of gas in the exhaust it self ( not in the fumes ) while I was cutting out the valance and while I was installing new tips.

All cops have been replaced as well as the plugs so the odor is more than likely not from un-used gas do to missfire.

 

[2k2ls]

YO! I changed my coils this weekend and when i was done i noticed the SAME thing. I have been trying to find a bad hose but havent been able to find one. Maybe a gasket? Not sure. If you find out please spread the good word

 

[JWerner2]

Are you talking about the whistle or odor?



I was thinking exhaust manifold gasket but I doubt it.

I also may add that the cats and entire exhaust have been replaced for the Magnaflow kit since the coils were replaced so its not just a left over odor.

 

[2k2ls]

the whistle noise. My motor is normally extremely quiet so this whistle was very obvious.

 

[97stscaddy]

Your engine is basically a huge 8 cylinder vacuum. When the engine is running those 8 cylinders are always trying to pull air through the throttle body, even when its closed. The butterfly valve in the throttle body does not close completely when its in the rest position so there is a small gap between the bore of the throttle body and the edge of the valve. What you hear, is most likely the rush of air around the butterfly valve in the throttle body. Take the air intake hose off and it will become VERY prominent. And this is completely normal, every engine does it, even if its carburetted.

 

[JWerner2]

I knew about that. This is not that. It is behind the manifold and TB area but slightly to the driver side. This was loud! Like I said it did not go away as I flipped the plate open it just got worse.


Thank you how ever I do appreciate it.