why is my car making a grinding noise, while pressing on the gas in park? on 1998 Ford Escort

It doesn't do this in drive, and also when it sits for too long, it wont start and has to be jumped, took the battery to Walmart and they said it was still good?

Get Your Car Fixed at a RepairPal Certified Shop.
We certify shops based on expertise, quality work, and verified customer reviews
1 answer
POSS STARTER DRIVE IS WEAK