Over heating prob on 98 bmw 523i se

check your fan relays

You may two problems and one symptom. you may have a blend door problem that is not allowing air to circulate threw the heater core. also you may have a bad connection or weak coolant temp sensor showing you erratic readings and it may have nothing with the heat in the vehicle. you need to eliminate or separate the one of the the problems to diagnose your one symptom.

there is no speedometer cable on these cars,they have wheel sensors on all wheels,check and replace senor/sensors. will also sometimes throw abs and ats lights on dash.not to difficult to change for a diy person

take out the glove box, you will see a white box about 3 inchs square with wires pulged into it, this is the diverter control,take the screws out, and remove it, then see if you cand move the diverter by hand too get heat, if you can then you need too replace the control or just lock the diverter in the heat position, i had this same problem last week in a 98 explorer and liked too never found it , ive got heat now!!!

SOUNDS LIKE YOUR THERMOSTAT IS STICKING,REPLACE THERMOSTAT FIRST OVERHEATING WILL DAMAGE ENGINE.IF THAT DOSEN'T WORK HAVE WATER PUMP CHECKED.FANS WON'T TURN ON IF HEAT FROM ENGINE IS NOT FLOWING INTO RAD BECAUSE THEROMOSTAT STUCK CLOSED,OR WATER PUMP FAILING

sounds like the crank sensor is bad.

when i bought my 98 stratus a year ago it was overheating too.I replaced the water pump,but when you do this you must replace the timing belt also,and since all this was fixed ive had no more problems with overheating/ good luck

Check/replace all sensors .. ECU

i agree water pump , but thermostat can go bad very fast some times they will have a defect when u buy them for that you can do a simple test ,,,put the thermostat in boiling water if it expands that means its working

Antifreeze may be leaking check carefully to see where exactly is the steam coming from and get back tome.