No exact idea, tho most I have seen, were where the upper radiator hose attached to the engine. There is often found a dome like part connected to the hose and it has a bolt or three holding the "dome" to the engine wherein resides the thermostat. "Look fer it!"
The thermostat on a BMW 525I is located into the water pomp in the thermostat housing.
rear wheel drive
The 1994 BMW 381 dipstick can be found on the left-hand side of the engine. The dipstick will have a yellow handle.
The thermostat on a 1987 BMW 325i can be found by following the upper radiator hose. The thermostat will be located on the side of the engine.
The thermostat is located on the front of the engine, between the upper and lower coolant hoses.
IN BETWEEN THE TIRE AND THE RIM
is in hard to replace a thermostat on a 2001 bmw 325i
usually in a removable housing at the engine end of the upper radiator hose
bottom left front of engine attached to elec water pump
on most inline BMW engines, the thermostat housing in located on the front of the engine, drivers side, in front of the intake manifold, between the airbox and fan. there are coolant hoses going in the bottom and the side.
The thermostat is in a housing just above the water pump on the front of the engine block. Follow the upper radiator hose, it goes right to it.
Go to the dealership or a BMW specialist.