If the vehicle is damaged and requires sheet metal repair or replacement, make sure the body repair shop applies anti-corrosion material to parts repaired or replaced to restore corrosion protection.
Original manufacturer replacement parts will provide the corrosion protection while maintaining the vehicle warranty.
Chevrolet Cobalt Service & Repair Manual. Engine Valve Seat Grind
It is usually recommended to send
head to machine shop for valve seat grinding.
A suitable valve grinding tool
kit is required to grind valve seats.
Valve guides must be in good condition
before grinding because a pilot is used in guide to center stones. ...