happens only when im not moving

[TheGreatSamG]

the car drives fine

doesnt happen all the time

but my engine has a knocking sound

its not tapping either

it comes from under the hood

and when i open up the hood its hard to find where its coming from

anyone have ideas on what that might be??

and when i roll down the windows my rpms drop??

 

[98GTPCALGARY]

it is probably your supercharger coupler. it is worn, when you stop, it sounds like rocks in your engine? if you take it out of gear, it usually gets quieter...

youtube...explanation...watch

YouTube - Replacing a worn out supercharger coupler on 3.8 GM engines

 

[blueguy]

Your rpm's drop when you roll down the windows...that sounds electrical...like your alternator might be taking a s**t on you...I'd have that and the battery tested too...not sure about the ticking though...might try that Lucas stop tick stuff from Slow Riellys or Advanced...and if it cures it up then you have valvetrain issues...

 

[TheGreatSamG]

thanks. i guess ill do that.

at first i thought anything dealing with the supercharger was complicated. guess not

and yea the alternator does seem like it does that.
i cant have the heat or a/c on blast while listening to my radio cause the lights dim or you hear the blower motor dropping from high to low at times.