DIY: (E9x) M3 Thermostat Replacement

[e92robert]

I had an issue with my Thermostat this past week and decided to replace it myself, I didn't feel like paying the stealer $979 for the repair. I looked around on the internet for a couple days and found NOTHING out there for E9x M3 Thermostat Repairs. So here are the photos and steps on how to replace it yourself.

Time taken to repair: 3-4hrs (mechanically inclined) 4-5 (mechanically challenged)

Total Spent DIY: $120.77
Price Dealer Wanted: $979.50

Tools Needed: 10mm socket, 11mm socket, 5/8 socket, T20 Torx, T25 Torx, T30 Torx, Medium length flat blade screwdriver, Long flat blade screwdriver, 8mm crescent wrench.

Preliminary: Remove the Intake system before the first step!

First: Take off the Intake Manifold. DO NOT unscrew the 2 bolts on the top. They have nothing to do with the removal. You will notice underneath the manifold, on the throttle bodies that there are clamps holding each one on. Unscrew the clamps until they are loose enough to pull the entire Manifold up and off. (There is a sensor underneath on the front side of the manifold that needs to be unclipped and there is another on the right back half that needs be be undone.) Pull off! (Pictures 2 & 3)

Second: Next you need to unscrew the 2 screws that mount the fuel line to the fuel rail. Right Side Only (Pictures 3 & 4)

Third: Now unlock the wiring harness of the fuel injectors. (Pictures 6 & 7)

Fourth: Now unclip the injection pipe out of the holder and lay the injection pipe, cylinders 5 to 8, to one side. (Pictures 8 & 9)

Fifth: Disconnect plug connection on coolant temperature sensor and on solenoid connection. Both are located on the upper right of the thermostat housing. Cover to make sure dirt doesn't enter engine block. (Pictures 10 & 11)

Sixth: Open up the coolant housing (Only when the engine is cold.) Under the car you will undo the front cover and drain the coolant from the radiator. (I think this part is optional but you can opt to do it.) Drain the coolant. (Pictures 12, 13 & 14)

Seventh: Unlock the coolant hoses and detach. Detach the coolant vent hose. Then unscrew the thermostat's 3 bolts. (Excess coolant will come out so make sure to have a sheet of cardboard under the car.) (Picture 15)

Eighth: Remove the thermostat housing forwards toward you. Clean all the sealing surfaces. Inspect the O-rings on the back half of the thermostat for damage. (Picture 16)

Ninth: Remove the thermostat from the housing. Check rubber section for damage. Insert new thermostat into housing. (Pictures 17 & 18)

Follow this tutorial on how to change the coolant out on the car and replace what you have drained. http://www.m3post.com/forums/showthread.php?t=706073

Now simply assemble everything back together and don't forget to put the sensors back!!!

I hope this helped as many people as possible. If you have any questions feel free to pm me or just ask.

[regular guy]

Nice DIY.

[e92robert]

Originally Posted by regular guy

Nice DIY.

Thanks!

[///mawana]

Originally Posted by e92robert

I hope this helped as many people as possible. If you have any questions feel free to pm me or just ask.

Super DIY and clear pictures ...

[Chicken Little]

nice post.

[phrozen06]

great diy

[e92robert]

Originally Posted by mawana

Super DIY and clear pictures ...

Originally Posted by Chicken Little

nice post.

Originally Posted by phrozen06

great diy

Thanks guys! I hope this can help someone who is going through the same garbage I was!

[Richbot]

What were the symptoms which prompted the repair? Thanks for posting, very nicely done.

[e92robert]

Originally Posted by Richbot

What were the symptoms which prompted the repair? Thanks for posting, very nicely done.

I was driving home from work, I downshifted while preparing for a turn and that's when a SES error code came on. The m-drive screen showed the error as "Increased Emissions." I took the car into BMW and I was told by the service advisor and tech that the car gave off the code P0128 which deals with the thermostat/cooling system. The reason the "Increased Emissions" error was displayed was because the thermostat was effected and down the line it effects the O2 sensors. Dealership wanted $979.

[phrozen06]

you didn't want to replace the waterpump with the thermostat?

[VictorH]

I just got the 2B59 coolant Thermostat monitor code.
Looks like I need a thermostat too.

Why do you have to remove the thermostat housing? Can't you just take the top cover off without removing the hoses or housing and pull the thermostat out the top and replace?

[VictorH]

Ok, got it. The thermostat is on the bottom and the whole assembly must be removed. What are the two coolant pipes leading under the intake manifold and how are those disconnected?

[e92robert]

Originally Posted by VictorH

I just got the 2B59 coolant Thermostat monitor code.
Looks like I need a thermostat too.

Why do you have to remove the thermostat housing? Can't you just take the top cover off without removing the hoses or housing and pull the thermostat out the top and replace?

a little easier said than done. i had to pry on my thermostat to get it out of the housing or I would have just left the housing in.

[e92robert]

Originally Posted by VictorH

Ok, got it. The thermostat is on the bottom and the whole assembly must be removed. What are the two coolant pipes leading under the intake manifold and how are those disconnected?

The thermostat housing should just slip out of those two metal pipes. You might want to replace the o-rings that sit inside of those pipes. Mine were fine so i just left them.

[e92robert]

Originally Posted by phrozen06

you didn't want to replace the waterpump with the thermostat?

When I bought the car in August the dealer told me that they had replaced the waterpump while it was in their care so I felt no need to replace it again... that is if they really replaced it....

[W///]

Awesome DIY, thank you! This will come in handy one day I'm sure

[e92robert]

Originally Posted by W///

Awesome DIY, thank you! This will come in handy one day I'm sure

No problem! I know it can be a pain to find DIYs for this car so I'll be on top of posting more in the future!

[urBan_dK]

THANK YOU for posting this. I want to tackle this job when it gets a little warmer. I got a P0128 in the cold weather and figured the thermostat was on its way out.

[e92robert]

Originally Posted by urBan_dK

THANK YOU for posting this. I want to tackle this job when it gets a little warmer. I got a P0128 in the cold weather and figured the thermostat was on its way out.

I would say that it is most likely the thermostat... Like mentioned earlier you might want to replace the water pump while pulling out your thermostat. Hope things work out!

[datninja]

I just did this last week, mind you I'm supercharged so it didn't take that long seeing as though the whole stock intake system isn't a part of the equation. I also found it is unnecessary to disconnect the fuel rail since it is a flex like that is hooked into the top part of thermostat housing. This probably took me and my buddy 30 min to change and 2 hours looking for the stupid hose clip that connects to the therm housing. I needed to pry the shit out the old thermostat to get it out though and it was pretty dirty around the edges. In the end, especially VF supercharged vehicles, this doesn't take quite as long.

[stevehifi]

what parts did you need for the install? Just the thermostat? If there are others can you post the part numbers?

Did you also reuse your drained coolant or replace with 50/50 Distilled water/Coolant?

Thanks,

Steve

[Agent-GHQ]

What yr is the car n mileage?