2000 BMW 323 heater broken, coolant leaking, engine overheating

3 days ago my warning light for low fluid lit up and I added coolant. The very next day the warning light came on again. All the coolant was gone and I noticed the leak. The same day my heater wasn’t working. The engine didn’t overheat until yesterday when I immediately pulled off the road and let it sit before driving it home. I’ve gotten different opinions on where the problem might be. Has anyone experienced this problem? If the thermostat is the problem, because the car has already overheated, would I also need a new radiator? Is there a way to figure that out just by looking at the radiator? Thanks for your help.

Where was the leak?

The bigger problem may be the damage done by overheating, perhaps a blown headgasket.

You’ve gotten several different opinions? Has anyone looked at the car?

The first step will be to pressure test the system. That should locate the leak. After the leak is fixed (which may require replacement of a radiator, a water pump, a heater core, or something else) then the T-stat will need replacing and things will need to be checked out. Unfortunately, by driving it around like this you may have done other damage. The more you drive it like this is the more likely it is that the engine will get destroyed. Overheating can be deadly to an engine.

Is it leaking to the inside of the engine or is it a visible leak on the outside?

The heater wasn’t working the day you noticed the low coolant. That may be why.

Overheating is usually caused from too low coolant or coolant entering the engine oil via a blown head or intake manifold gasket.

A faulty thermostat, plugged radiator and/or rad hoses or plugged heater hoses or heater core will also disrupt coolant flow and can cause engine overheating.

You can check for coolant flow in the rad by (Having the coolant reservoir full first)
removing the rad cap when the engine is cold and starting the engine and let idle and look in rad.

(UNLESS this has a sealed system, in which case the only place to refill and check the level is in the pressurized coolant reservoir)

Do not remove the cap on a pressurized coolant reservoir unless the coolant is cold or very cool. (Loosen slowly)

Any time coolant problems happen have them looked at right away. Same issues like a thermostat can lead to catastrophe’s like blown head gaskets or ruined engines due to excessive overheating.

Take it in there is too much guessing going on and it still appears your driving it.

Stop driving the car and have it repaired by a competent mechanic / shop! Otherwise, it will stop driving you !

The problem is the leak. The overheating and lack of heat are due to the loss of coolant. Fix the leak ASAP, you do not want to let that engine overheat, it could be very expensive.