2011 CHEVROLET CAPRICE Structurebody Problems

WENT UNDER THE CAR, JUST PURCHASED FROM CITY OF WALNUT CREEK AUCTIONS, A 54K MILE EX-PATROL CAR...TO CHANGE THE DIFFERENTIAL OIL. FOUND TWO CRACKS ON WHAT IS A TENSION HOLDING BRACE IN THE LOWER SUSPENSION SUB-FRAME. SIMILAR ON EACH SIDE. OBVIOUS ENGINEERING DEFECT COMPOUNDED ON HOW THE WELDMENT WAS DONE. I PHOTO'D THE TWO SIMILAR CRACKS, THEN DRILLED AT THE END OF THE CRACK TO RADIUS THE STRESS POINT IT UNTIL THE ISSUE IS RESOLVED. THE CAR HAS BEEN UNUSED SINCE JAN 18' AND IS NOT RELIABLE UNTIL THE ENGINE NOISE IS REMEDIED, ANOTHER DEFECT I AM NOT SURE OF WHAT PART YET. IT IS A SCRAPING TICKING SOUND, LIKELY PISTON SLAP OR VALVE LIFTER. THE CITY WOULD HAVE CHANGED/ MAINTAINED THE VEHICLE TILL THE LAST 5K MILES BEFORE IT WAS "RETIRED." IT IS MOST NOISY WHEN COLD, AND MORE PREVALENT THAN NOT. LIKELY THE CRACKS STARTED MANY THOUSAND MILES...