2002 530D E39 check coolant


Hi All,2002 530D E39 about 290,000km has water but is announcing check coolant. There’s coolant but I topped it up anyway. No change. No puddles under the car, no water anywhere… the coolant hoses don’t get very hard when you start the car so maybe low pressure? Would it announce low coolant pressure? Maybe a water pump? Temp on the care is fine… doesn’t overheat… but it is about 3C here today…

My experience with e36s is that after about 10-12 years, the tube in the middle of the plastic external coolant reservoir starts to crumble. Water actually moves (circulates) in that reservoir while the car is running. I don’t know if the water moving in odd ways moves the float, or whether the chunks of plastic I found in the bottom of the reservoir were obstructing the float movement, but I got false low water messages until I replaced the reservoirs on both my e36s. I would expect that the design and materials of your e39 are similar.

If you have not yet replaced the radiator and hoses, you might want to save up a bit and replace everything while you have it apart. Water pump, thermostat, everything. The only part of this job that is difficult are difficult are the heater hoses. On an e36, those are a bugger. On my wife’s car, I replaced them as preventative maintenance. On my car, I left them in place until they fail because I dread the job.