During the extended weekend, we decided to replace the thermostat+gasket in or 2005 Mini Cooper S. We had noticed a small drip under the garage floor, and decided to replace it before it got worse. There's lots of great help on the internet regarding this procedure, this guide is extremely useful. (Note that you don't need to remove the ECU, just simply flip the airbox out of the way. This is discussed ad naseum in the comments.) This post is instead to just point out a we made when doing ours, hopefully to make someone else's life easier.

After installing the new thermostat you have to refill the cooling system and bleed it out again. At this point, when we started our car, the fans instantly shot up to maximum speed and the water temp gauge (the only other gauge besides the gas) shot up all the way to the maximum as well. The coolant temperature was reading a solid 143 on the OBD.

What we found was that in the process of the installation, we had knocked free the temperature sensor. I didn't take any pictures (unfortunately), but I was able to find this picture online that points out the sensor.



Make sure that's plugged in, if this happens to you. In fact, dismount the airbox, flip it out of the way, and make sure EVERYTHING's plugged back in before you freak out. We thought we were in for a hefty service bill at the dealer as a result, but luckily we were able to locate the problem.

I'm expecting this post gets buried, and that's fine. I'm really just posting this in hopes that someone with a similar problem will search and find this thread. I've attached the image as well just incase Imgur removes the image

Happy motoring!

 

Exact same thing happened to me during a clutch replacement. Start the car, temperature gauge instantly shoots up to max. Thanks for the photo showing exactly where the sensor is!

 

thanks for the heads up, I've done this once without problems, but it's good to know about if I ever need to do it again.

 

Excellent commentary, and thanks for sharing! For those needing to tackle this job, here's a video that may help:


Drive Hard. Drive Safe. Keep Grinning.

 

That's a second gen car, this is a first gen thread.

 

Correct! And there are good lessons that can be learned from the video

Drive Hard. Drive Safe. Keep Grinning.