Overheating: 1999 bmw 323i m series 2.5 ..Installed: new water pump , thermostat. radiator,new Water Reservoir, cap.. hose on top side hot , lower hose cold even when engine is hot..no water circulating at all...removed thermostat and still no water flow ? what could it be ? 911 .. help

this sounds like a coolant flow problem. possible rad plugged or water pump problem.

Well Michael put your hand on radiator upper hose and then the lower hose right after car warms up and just starts overheating is there a temperature difference if so one of two things is going on thermostat not opening even though it is new or there is still an air bubble in the cooling system if nthere is no difference and still overheating might have to explore headgasket being blown

HI Anon.
Remove your radiator cap (WHEN ENGINE IS COLD), run the motor and let it warm up a minute or two, have someone rev the engine a little while looking into the radiator. If the water goes down and/or you see the water moving, your water pump is good. If not this means that your water pump is bad and is not moving enough water through the system. Try Removing your thermostat and run the engine without it. Keep checking the radiator hoses to see if they are the same temperature. If they are not the same temperature the water pump is bad. If they are the same temperature your thermostat is more than likely the culprit. Hope this helps.

SOUNDS TO ME LIKE YOUR HEAD GASKET HAS FAILED

COULD BE THERMOSTAT IF TOP RADIATOR HOSE IS NOT HOT AND BOTTOM RADIATOR HOSE GOING TO WATER PUMP IS HOT THE THERMOSTAT STICKING PARTIALLY CLOSE.IF TOP HOSE IS HOT THE RADIATOR,ENGINE BLOCK HEATER CORE NEED FLUSHING OUT.IF WATER PUMP WEEP HOLE LEAKING REPLACE WATER PUMP, FAULTY WATER PUMP WILL CAUSE ENGINE TO OVER HEAT.REPLACE RADIATOR CAP MAKE SURE YOU HAVE 50 / 50 MIX SOLUTION ANTIFREEZE AND WATER IN COOLANT SYSTEM. IF ALL LOOKS GOOD CHECK ENGINE OIL ON DIP STICK, IF OIL IN DIP STICK LOOK LIKE MILKSHAKE YOU HAVE BLOWED HEAD GASKET THAT WILL CAUSE ENGINE OVERHEATING WHILE DRIVING CAR IN SHORT DISTANCE AND ENGINE OVERHEATING.

Most likely cause - thermostat has failed and is stuck shut.
Other possible causes include foreign material in the air fins obstructing air flow, or silicate or hard water deposits inside obstructing water flow, or air in the cooling system. Air gets in when you change the coolant, or when the plastic water reservoir starts to crumble and leak internally.
Also, BMW used a plastic impeller water pump off-and-on in the three series through the years. Those plastic pump impellers get old and crumble eventually.

your thermostat is a black piece of plastic just above the water pump behind the water pump pulley. both radiator hoses go to it.

There is a blockage or leak in your cooling system. That may come in a few different forms:
Incorrectly installed thermostat
Water pump not functioning - you may see water dripping from the pump or a stain from the hole under the water pump.
Severely coroded hoses/coolant passages - if the fluid is brown and the inside of the radiator rusty
External leak - you would see fluid on the ground Internal leak - you would see steam/white smoke from the tail pipe or water in the oil (may look like chocolate milk or not), if the oil level is extremely high this would be a good indication
heater core bypassed

Change thermostat.

Where is the water pump on 94 BMW 318, Is it behind the Fan or a seperate unit. is it easy to replace?