Grinding Noise

Please give more description about the grinding, as well as exact location...

 

No dash codes so its mechanical.

Listen under the hood while someone starts up the car. if that does not work get under the car and have someone start it while you listen to see where its at. May have to jack the car up and climb under there to pinpoint.

Not much in the rear of the car can grind when the car starts. Grinding on start up is not good.

 

Heat shields can buzz or rattle, though, and may only do so at certain engine RPMs.

 

Yeah that's a good one exhaust heat shields and those thin pieces of metal that are held up to the underside of the floorboard of the car with these little 10 mm headed bolts if you flick the edge of one of those it'll twang and make a noise like a musical instrument almost and if those bolts are in a rust belt and they start to fail there's several of those plates down there and they can get the singing the tune that sounds right crappy and then if left to continue on the sound could even get worse before it gets better and then the plates may fall off so if the underside of the car is rusty or you're in places where cars rust away someone may just be able to reach up under there and yank them off and they'll just disintegrate in their hands and the noise might stop but in the back of the car there's pretty much nothing to happen even with the wheels turning nothing back there Plus it's something you've picked up off the road and is stuck up under a wheel well or in between the rear wheel and a piece of suspension part something kind of like playing cards clothes pinned to the rear stay to flap in your bike wheel if you remember those sort of things A garbage bag and things like that come to mind.

 

So, that's what it sounds like, but did I read right that you hear it even when the car isn't moving down the street? And it goes away in certain conditions, even when you are moving down the street. So while it may be like a scrape-on-the-street sound, it clearly isn't one.

Those are places where some heat shields are, and they can sound a whole lot like that.

 

I agree that this is one of the reasons! But you need to first examine everything visually and then draw conclusions! Move from simple steps! Maybe something is stuck or dangling from below, you can only visually see it, and then look at the technical points!