2017 Mazda Mazda6 Engine

Coolant leaked into my engine system . Now dealership says a new engine is needed

I have a 2017 Mazda 6 that has an extremely loud engine. I have taken it in and I’m told the car is fine but I can feel the engine knocking through the pedal as I drive. The sound has gotten louder over time and it’s not getting any better. I’ve had some belts change and keep up my regular maintenance and Mazda can’t seem to figure out what the issue is. I have friends with the same model and their engine sounds normal.

I BOUGHT MY 2017 MAZDA 6 BRAND NEW. WHILE THE CAR WAS IN WARRANTY IN JANUARY 2020 WHILE I WAS DRIVING WITH 50 MILES IN HOUR, THE ENGINE WAS RUNNING ROUGH, THE ENGINE LIGHT WAS ON AND THE ENGINE STALL. THE CAR WAS TOWED BY MAZDA AT DEALER. THEY REPLACED THE FUEL PUMP AT THAT TIME. FEW DAYS AGO WHILE I WAS DRIVING WITH 35 MILES IN HOUR THE CAR DID THE SAME THING. MAZDA TOWED THE CAR TO ANOTHER DEALER. AFTER DIAGNOSIS THEY TOLD ME THAT IS NOTHING WRONG WITH THE CAR AND THE CAR IS NOT UNDER THE WARRANTY ANYMOORE . I TOLD THEM THAT THE ENGINE LIGHT WAS ON AND SOMETHING MUST BE WRONG. THEY DIDN'T RESPOND. THE CAR HAS 24,000 MILES AND I AM AFRAID TO DRIVE IT ANYMORE.