What could the problem be on a 97 dodge ram if antifreeze still leaks badly even after the thermostat has been replaced and the radiator and pump was pressurized by a professinal and found no leaks?
Where is it leaking? That pressure test sounds funny, why would you pressurize only the pump and radiator? If you are leaking coolant outside the engine, locate the source. If you are losing it from the radiator but cannot find a puddle suspect a head gasket problem. Check the Radiator cap first, if it is bad high pressure coolant will travel back to the overflow bottle.
The best indication of a bad thermostat is when the radiator fluid (Antifreeze) boils over from the reserve tank, not the radiator. This is caused by the thermostat not opening at its preset temperature and all the extra antifreeze is pumped directly to the reserve tank. You will also have loss of power and the vehicle will likely stop running soon after the antifreeze boils over.
Drain the radiator into a container. Remove the upper radiator hose at the engine end. there is 2 bolts in the housing that hold the thermostat. Remove them and the thermostat and clean both surfaces. Install the new thermostat and housing. Install the upper hose and top off the radiator with a 50/50 mixture of antifreeze and water.
generally located where the upper radiator hose meets the block, under the throttle body Follow the upper radiator hose to the engine, there should be the thermostat housing. And there is no drain plug on an 2002 Monte Carlo 3.8 v6 , so you will lose less antifreeze if you just disconnect the upper radiator hose from the thermostat housing then hold that hose up. I only lost maybe a quart of antifreeze.
Follow the upper radiator hose from the radiator to the engine. The thermostat is located within the housing where the radiator hose connects tot he engine. Drain radiator, remove hose from thermostat housing, remove the bolts that fasten the housing to the engine and pull off housing, pull out thermostat noticing the direction it is pointing. Installation is reverse of removal (making sure thermostat is facing in the right direction). Refill radiator with 50/50 water/antifreeze…