Q: My engine is over heating and there no heat coming out in the cabin when turning the heat on, I've replaced the water pump and the

Trapped air can cause both overheating, and lack of cabin heat, so hopefully after you replaced the thermostat, all air was purged from the cooling system. Assuming the cabin heater control valve is functioning, a common reason for no cabin heat during overheating is the coolant can boil, create trapped air and that trapped air then blocks coolant circulation to and through the heater core. Of course, it is also possible that you coincidentally (coincident to the engine overheating) have a blocked heater core and/or, as noted, a malfunctioning heater control valve. In any event, the most important thing is to fix the overheating problem first as overheating can damage the engine. The most common causes of overheating include low coolant level (including that due to leaks), a faulty thermostat (obviously, you just replaced yours), a plugged radiator, a faulty radiator pressure cap, collapsed hoses, non functioning cooling fans, and a faulty water pump or drive belt. Certain engine faults, such as a leaking head gasket, poor engine running condition or exhaust blockages can also cause overheating. If you desire that this overheating problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an engine overheating diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.