[slowblackx3f25]

So couple weeks ago, my dads x3 had a loud engine fan working right after getting off the highway and it kept running fast and loud.

We pulled over to a Starbucks parking lot, and popped the hood, noticed the engine cooling fan working fast and loud.

Turned off the engine, push to start to turn the engine back on, same issue - loud fan, fast fan speeds.

Check Engine light on the dash.
Brought the x3 to a BMW specialist shop, code came out for thermostat.

Replaced thermostat and the issue was gone.

Normal fan speeds. It gradually slows down now when I get off the highway. Doesn't stay fast and loud like before.

This is due to the thermostat stuck closed.
Replaced OEM TS (Mahle).

Few days later. Same issue. Loud fan speed and CEL.

Brought it back to my BMW specialized shop and it was a code for thermostat AND a temperature sensor.

Replaced the sensor and boom! Back to normal.

No more CEL or fast loud engine fan spinning.

I hope this helps someone if they experience this from their BMW's.

BUT, ALWAYS bring your BMW to your shop (that's super good with BMWs) and SCAN for codes, prior to deciding what it is.

I'm glad it did throw a code, it was easier to diagnose and repair.

Oh, and CAA towing service came in clutch. This all happened in the early morning AM hours before I head out work… but my dad was in town so my dad helped me take care of it.

Keep those BMW's running fellas!!!!

And I hope the water pump and other sensors stay in good shape for another 50k km. My x3 is at 135,000KM as I type this.

I will be replacing spark plugs and maybe brakes next, also looking at doing carbon cleaning at approximately 150k km's.

[Bdavi011]

By any chance do you have the part number of the temperature sensor that was replaced? This happened to my X3 2 months ago and it only happened once. I let the car sit after the fan was super loud and when I came back to the car hours later it never came back. I replaced my thermostat and water pump around 75k I think? Would have to double check my records but I'm currently at 96k miles.

Thanks again!

[slowblackx3f25]

Originally Posted by Bdavi011

By any chance do you have the part number of the temperature sensor that was replaced? This happened to my X3 2 months ago and it only happened once. I let the car sit after the fan was super loud and when I came back to the car hours later it never came back. I replaced my thermostat and water pump around 75k I think? Would have to double check my records but I'm currently at 96k miles.

Thanks again!

I don't have the part number on the invoice.
I do know that there's three sensors and only one was replaced.
(coolant Temperature sensor)

Did you do the thermostat and water pump replacement together?


I was told the water pump is good, so I only replaced the thermostat… why replace a part that's not faulty?


If it happened only once, and there's no CEL/codes, you should be fine… IMO.

[383vett]

You should have replaced the water pump while the thermostat was replaced. They are next to each other and it's a good time to do both. Getting there is 90% of the work.

[slowblackx3f25]

Originally Posted by 383vett

You should have replaced the water pump while the thermostat was replaced. They are next to each other and it's a good time to do both. Getting there is 90% of the work.

The shop that installed the new thermostat said they never changed the water pump on any of the x3's they did a thermostat replacement on, so we didn't bother replacing the WP…

And all the x3's this shop installed thermostats on never came back for a water pump replacement… at least not yet, and I hope no one has to get a water pump install. Not the cheapest replacement part.

If I did the water pump, I would've changed the thermostat, but since it was just the thermostat, I didn't bother replacing the WP.

I believe our x3's use's the GMB water pump system.
I checked the part out on RockAuto.com, kinda pricey… 700$+…

[okayr]

If it comes back- have them check the transmission cooler. I spent a total of at least a month and 5 trips to 2 different shops to get this fixed...

I had my thermostat replaced and then coolant sensor replaced. BMW specialty shop then did thermostat again, then thermostat AND water pump, then FINALLY they figured out it was the transmission cooler and I haven't had a problem since. But it was a major major headache and even was baffling the bmw shop.

[slowblackx3f25]

Originally Posted by okayzac

If it comes back- have them check the transmission cooler. I spent a total of at least a month and 5 trips to 2 different shops to get this fixed...

I had my thermostat replaced and then coolant sensor replaced. BMW specialty shop then did thermostat again, then thermostat AND water pump, then FINALLY they figured out it was the transmission cooler and I haven't had a problem since. But it was a major major headache and even was baffling the bmw shop.

Thank you so much for taking your time to share this experience!!!

I will continue to drive my x3 and see what happens.
I'm hoping no more CEL's… it ruins the entire day.

I'm happy you got it fixed… eventually.

Sometimes it's a drag… it's worth it at the end though! Once you find out what's wrong and replace the part(s).