I have a 1995 Ford contour and it keeps over heating we replaced the thermostat and we hear a rattle noise sounds like a diesel truck or. Marbles in a pop can when accelerate. It gets louder. We tried headgasket. Sealer but still hearing the noise. I need. Hel please asap

Do a compression test. Overheating could be a head gasket.

Sounds like a blown head gasket. Have the aluminum head checked for warping and the valves examined, if you decide to properly fix it.

I would not drive the car or even run the engine until it's diagnosed.