How To Replace a Thermostat and Coolant Temp Switch on BMW M3 E90

#E90M3 #BMWM3 #M3
After getting a CEL, I determined that my thermostat was bad. I have noticed previously that the car took unusually long time to warm up. I decided to put together a short video on thermostat replacement. While I was in there, I also decided to replace the main coolant hoses as well as the temp switch. I also flushed the coolant.

[@cloumecloume]

Thanks for the video! Besides removing the plenum and intake components, this job was straightforward and simple. I pumped out the coolant from the reservoir only (maybe 1 to 1.25 gallon?), placed a thick towel under the three connecting tubes, and disconnected them from reservoir tube to middle large tube to right most large tube in the order while positioning the two large tubes upward to prevent any further spilling. There was maybe half cup of coolant spilled on to the towel. After everything was put back, I refilled the reservoir with a new coolant and distilled water mix about 1 to 1.25 gallon. Did the engine on with heat on process twice, drove around for 15 to 20 minutes. Once the engine cooled down, rechecked the coolant level, refilled another half cup or so of coolant. No leak and all is well. Btw, the pumped coolant was clean blue color.

[@CarGuy1]

nice! The self-bleeding cooling system makes things easy.

[@renaudy2092]

Hey man, you are one of the few to consider draining coolant before removing the thermostat housing instead of having all the coolant leaking on the belts. I don't know why people keep doing that. Anyway great DIY

[@micraw714]

Nice work! I just finished mine about to start it up. Praying for no leaks haha

[@CarGuy1]

Yeah, I think I got lucky and didn't damage any of the o-rings. Hopefully you had no issues with yours.

[@micraw714]

@@CarGuy1 thanks, I didn't get any leaks so all seems good! I used quite a bit of silicon lube as well, I was paranoid about that from reading the forums 😄

[@m.cooper1854]

Thanks for this. I have a 2008 E93 M3 that has thrown an intermittent "Increased Emissions" warning. The code reader says it is due to a cooling system issue. Pretty common for German cars after 10 years to get a stuck open thermostat. The ECU decides it has taken too long for the engine to reach operating temperature, and then you get a Check Engine Light and a code.

[@davemanzombies3853]

how long can you drive it like that without replacing it? i have that code too... sadly lol =[

[@CarGuy1]

@@davemanzombies3853 I wouldn't drive it like that for too long. Driving the car that doesn't reach its full operating temp can't be good for the engine.

[@m.cooper1854]

Depending on the climate, it's often just an issue of taking too long to reach operating temperature compared to what the ECU thinks. However in a cold climate in the north, a stuck open thermostat is a concern and will deteriorate fuel economy at a minimum.The thermostat is not an on/off switch. It is designed to move from closed to open depending on several inputs.

[@jleyva92]

Does this cause a constant running cooling fan ?

[@kywolf2320]

Great video! Could you pretty please tell me about how long this job took you. I am being told by multiple mechanic shops that it is 5 hours labor. Looks like 2 hours at most. Thank

[@CarGuy1]

Probably 2 hours and that included setting up for the video (even for such a crappy quality - it's a hassle). It's not a difficult job at all.

[@AT-tg1ny]

How much coolant did you need to fill after draining the radiator? I have thermostat and sensor sitting in my office for the last 6 month 😳 that I need to get to at some point. Also, do you think replacing the coolant pipe is necessary? My car is 2011 and 50k miles... It's probably better to replace but as you mentioned, I hear they are pain to get off...

[@CarGuy1]

If I remember correctly - I used 2 gallons of the 50/50 mix. You're not truly flushing the whole system (which would require you to drain the block), so you shouldn't need a lot. If you are referring to the coolant hoses - I think you are ok to keep your current ones. I had more than twice your miles and mine were in good shape. I just did it for the peace of mind and because they are pretty inexpensive.

[@matthias_372]

25:00, rubber mallet ist not really the best idea. I aways spray the 8 rubber joints of the throttle bodys with silicon spay. This works a dream

[@mu6554]

Did you run the car before putting everything back together to see if there are any leaks ?

[@CarGuy1]

I did not, but it's not a bad idea to do so. Fortunately, in my case, there were no leaks.

[@jayd1008]

did the check engine light go off after the install ?

[@CarGuy1]

So there wasn't a check engine light to begin with. The car took exceedingly long time to warm up. I hooked it up to ISTA and saw the issues with thermostat.

[@davemanzombies3853]

how long can you drive it like that without replacing it?

[@nataliamiliano150]

You should not drive it at all! Your engine can overheat, and ruin your engine.

[@Xsocto18]

Hi ! do i need to emptey the coolant before replaceing thermostat ?

[@CarGuy1]

not entirely, no

[@Xsocto18]

@@CarGuy1 so i only need to remove the thermostat and replaced with new with out bleed the system ? :D

[@CarGuy1]

@@Xsocto18 Any time you open the system, it needs to be bled. With that said - these cars "self-bleed". I would keep an eye on the coolant level for the first week or so.

[@Xsocto18]

@@CarGuy1 Okei thank u!! :D

[@anttheman6370]

Did you’re code ever come back after doing this ?

[@CarGuy1]

It has not.

[@anttheman6370]

@@CarGuy1 thanks man I got a P1208 code on my e92 m3 recently and going to get it taken care of

[@anttheman6370]

Why couldn’t you get the cover seated correctly?

[@CarGuy1]

I did get it in, but it was a bit of a PITA. I don't think I would have any issues if I had to take it off and reinstall it again.

[@anttheman6370]

@@CarGuy1 why did you have trouble putting it in? Was there a bolt you couldn’t reach? I’m asking because I am doing this myself very soon

[@anttheman6370]

@@CarGuy1 ?

[@CarGuy1]

@@anttheman6370 just to be clear - you are referring to the intake plenum, correct? If so, lining up the "tubes" on the plenum with the rubber boots took some work.