The time finally came when I said, I’m really tired of seeing this engine light on my BMW’s dashboard. I was pulling code P0128 on my OBD 2 reader, I knew it was a bad thermostat so I took the proper measures and said lets do this. Ordered my BMW E65 E66 thermostat part and to the garage we went. I really won’t be able to describe the project as well as if you just watch the diy Bmw E65 E66 replacing your thermostat project that I have on YouTube. You can see that video below. This project was done on my E65 750i, I believe the earlier model E65’s E66’s, 4.4 Liter engines it’s easier to get to the thermostat.
Important Tools For This Job.
10mm socket with a choice of different socket wrenches.
Razor blade or paint scrapper for old gasket removal.
New 1 Gallon of BMW Coolant & 1 Gallon of Distilled Water.
T30 or also called Torx Bit 30. (You can see this is video below)
Flat Head Screw Driver
New Lower Hose & Lower Hose Sensor
Problems I faced with this project were as follows, I had trouble removing the lower hose from the thermostat, again my car is a 2006, this car has never had the lower coolant hose removed before and again this hose is slotted so don’t twist it just wiggle it again and again until you get it loose. That was pretty much the only struggle other then that back 3rd 10mm bolt that holds on the thermostat, again pick your favorite weapon (tool) of choice and you’ll get it.
Again other projects you should consider if you have the money at this time would be to replace your BMW E65 E66 water pump and belts, during this project examine your water pump for gasket leaks and wiggle your water pump pulley to see if you have a bad water pump bearing, also examine your belts for worn belts. Also examine your lower coolant hose as well. If you decide to replace your BMW water pump later as I will do, then you will have to replace the BMW coolant again.
Watch the video below videos speak a 1000 words, and Thank you for watching, and Happy Fixing.