spector551

Hi Guys,

I hate for my first post to be one of this nature, but I need some opinions from you BMW champions.

I have a 2007 525i (actually made in 2006) and the fan radiator fan is blowing wide open in it most of the time. When I turn the car off, the fan spins down like someone just killed the engines to a jet.

I have read about the water pump issue, but I don't think it's the water pump because I drive 150 miles round trip to work and back in the south Louisiana heat (high 90's) and have been doing it for at least a week with this condition. I have never gotten a message about overheating or anything else for that matter. Sometimes the traffic is stop and go but still no overheating.

What would make the fan go bananas like this but the car isn't overheating?
Is there a fan relay in my model that can be screwed or would the fan itself be screwed? Any advice would be much appreciated.

tonyb635

I doubt its a water pump unless u see an over heat msg. My guess is a sensor making the car think its over heating which then puts the fan in high speed. A friend of mine has a 07 530 and he changed two senors and I believe he said they were on the top rt side of the radiator. Maybe look around. You coud also find someone with INPA software and have a look to see if there are any codes thrown. There coud be a few clues in there even though u don't have a CE light on.

dbond

Drop by Autozone or similar store and read the error codes. They won't give you BMW specific codes but it still could be helpful. Without the codes we are just playing the guessing game.

spector551

Oh, yeah - I forgot to mention that during this time I was unknowingly traveling without my hood fully latched. I noticed it barely moving but thought it was some sort of optical illusion. When I checked it, it was indeed not fully latched. Would this have affected anything?

BimmerFan52

When you first start the cold engine (without the AC on) does the fan run immediately? If so, then it is very likely a temperature sensor, as one earlier poster pointed out, with the auxiliary fan relay being the second likely suspect.

One way to get a look at the sensor is to pull up the secret menu just after starting the car to see what the ECM thinks the sensor is telling it. Some cars default a missing sensor to 212F as a safety to insure the engine doesn't overheat and of course this will signal the fan to come on.

Fan relay is about $35 and a coolant temperature sensor in lower radiator hose is about $20.

e6t.lab.rat

The sensor on the lower radiator hose reads the temp of the coolant leaving the radiator (coolant going into the engine). If this temp is too high, then the fan will kick on. Pretty much what this guy ^^^ (previous post) is saying. Sounds to me like you have a bad coolant temp sensor. This is a fairly simple DIY without having to drain your coolant. I'd start with this repair first.

Couple of years ago my sensor leaked and needed to be replaced. This is how I learned what this sensor does. Good luck

Mmichel907

I have the same issue on my 2007 525 i. I've changed the coolant sensor on Saturday but the fan went off again today. Did your got fixed. If it did could you please let me know what you did to fix it. Thank you

Jnelson1182

I have a 04 525i an for some reason I keep having my coolant boil over and splash out, I think its because my fan isn't kicking on can anyone please tell me a method to test this?

seanjordan20

Yes get the engine to operating temp and look and see if the fan is kicking on and off. Unless you have INPA.

Jnelson1182

ok so I fixed my issue, as far as I can tell. it was the thermostat being stuck open, how that ended up making coolant boil over the one time idk but it was preventing fan from coming on at all unless I turned on ac because the car wasn't getting passed 82c at the highest, I replaced thermostat an coolant resevor an now things are back to normal when it comes to the fan kicking on an off as well as I haven't had to add any coolant since the fill following repair. the car is also running better now that it is reaching operationg temp.