[conmanxtreme]

I hate to say it, but I would check for corrosion on your DME. I had water damage in mine, caused it to short out and make the water pump continuously run, ended up killing my battery and making all kinds of stuff go haywire. Ended up getting a cloned DME and all is well now.

[Meeni]

Looks like the thermostat temp sensor sending HOT HOT HOT signal, which will make the pump run constantly. The fan should also run in that case.

The electronic on the pump itself is also known to fail, but if that's what it is, that's a new "symptom" for that disease.

[Three_thirty_I]

Originally Posted by Meeni

Looks like the thermostat temp sensor sending HOT HOT HOT signal, which will make the pump run constantly. The fan should also run in that case.

The electronic on the pump itself is also known to fail, but if that's what it is, that's a new "symptom" for that disease.

This is what confuses me about the E90 cooling system on the N5X engines. There are two temperature sensors, one at the radiator outlet, and one at the heat-exchanger which measures oil and coolant temperatures. But then the thermostat and the electric pump play a part in all of this too. So what does the ECU look at to determine which temperature map it has to have the engine run at? Sorry, this is a bit of a thread hijack, but in the case of my N52, I have been battling with an "over-cooling" problem for years now, and have replaced both temperature sensors (that was the first suspicion), then I replaced the thermostat (also new OEM part), and then had the ECU tested and reprogrammed (latest software). Still no difference, and I still see mostly 74 to 84 degrees Celsius temperatures when I look at the coolant temperatures on cluster's hidden menu 7. Typically it will either initially or randomly climb to 96 degrees, but then short lived it quickly drops back down to the ~80's. And just to reiterate, no error codes or anything to suggest that there is anything faulty or not functioning properly. The reason for asking what dictates the temperature maps, is that it is as if the ECU is stuck trying to keep the engine in "mapped high output mode" which is around ~80 degrees, but it is never able to get to the proper "eco mode" which is around 105 degrees. The ECU specialist at the time insisted that my concerns about the temperature issues (wasn't the reason why they had the car BTW) was unfounded and that the "internet" is wrong saying that it should typically sit around 105 degrees most of the time under normal driving conditions. I have seen too many videos of similar cars showing these higher temperatures, a family member's X3 which has the N52B25 engine runs at these higher temperatures, so there's definitely something not quite right. And one thing that I do recall many years ago that is different is that previously in winter you could feel how the climate control warms up the air coming in even though the temperature is set to 18 or 20 degrees, since I was aware of the cooling issue, the only way to get the cabin to warm up is to turn the vent dial to red and/or increase the temperature on the climate control. So I am wondering if the last link in the chain could well be the cause, that being the electric pump??

[EB89]

Hey guys, FYI this issue is more than likely the JB4 ISO bug.

The JB4 if powered from the standard 50amp fuse is powered when the car is off and tells the pump to run.

It's rare and I don't think anyone knew way circumstances cause it to happen.

Need to do the JB4 power bypass mod

I had this and removed my JB4 completely which fixed the problem

Here is the mod
http://www.n54tech.com/forums/attach...1&d=1436499825

Here is a thread about it
http://www.n54tech.com/forums/showthread.php?t=31842

[Vongolet]

For me it was my water pump that was broken, so I replaced it and the car has run fine ever since.

[firmmd]

I have a 2014 BMW X5 3.5i N55 engine. 2 days ago I replaced the thermostat because the old one was stuck open and the car would not heat up (winter in NY) even after 1 hour of driving. Thermostat change fixed this issue and now car warms up normally but now the damn water pump runs all the time. If I open the door, it turns off for 3 min and then runs again.....
Water pump keeps running and drains the battery
Did replacing the damn pump fix the issue????

[Kbudz94]

Originally Posted by firmmd

I have a 2014 BMW X5 3.5i N55 engine. 2 days ago I replaced the thermostat because the old one was stuck open and the car would not heat up (winter in NY) even after 1 hour of driving. Thermostat change fixed this issue and now car warms up normally but now the damn water pump runs all the time. If I open the door, it turns off for 3 min and then runs again.....
Water pump keeps running and drains the battery
Did replacing the damn pump fix the issue????

did you do any of these fixes man? what did you find.

[MiBmer]

Just wanted to say that thanks to this thread, I was able to repair my battery drain issue. Replacing the water pump fixed it for me.