I just bought a 1997 Pontaic Bonneville a couple of weeks ago. It has 118,000 miles on it, and runs well. The only problem is, there’s there’s faint sort of whistly noise under the hood. It doesn’t seem to change intensity when I drive the car. It’s just always there. Two mechanics looked it over, one right before I bought it, and one right and after, and both pronounced it “a pretty good ol’ car.” One even said he thought it could easily go another hundred thousand. So–did they miss something big? Like an engine bearing or something?
I know you said the whistling noise " doesn’t seem to change intensity’, but I suspect a vacuum leak.
Check all vacuum hoses for cracks.
Perhaps a leak around the maf sensor/throttle body area. Check the intake manifold bolt torque too.
Another possibility coud be a pulley bearing. A water pump or power steering pump?
Some noises are next to impossible to locate. Persevere.
I checked the previous owner’s maintenance records. The water pump was replaced in '04.
I’ll take a look @ the other stuff. Power steering pump is good.
I ve had the whistling sound few years ago and got louder until it reached a phase that all my neighbours knew i was coming home from the loud whisle!
I googled it a dozen times still nothing.
Once i was looking for some cracks or anything that looked wrong and i found that mu pcm valve was loose!
So i replaced it and it went ok. Got rid of the sound!
Also note that when i had the issue i had lots of air sucking when i try to remove the engine oil cap… so strong that i had to pull reaaly hard to take it out
Your helpful info is in response to an 11 year old post. The poster and the car are long gone
Yeah old but just for the sake of clarity, what’s a PCM valve? Are we talking the powertrain control module or the PCV valve or something else?
Im sorry for the mistake… it is the pcv valve!