2002 X5 E53 3.0i Coolant Reservior replacement and Air Intake Boot replacement

[jdudjak]

Fellow X5 owners, I was stranded on the road because my coolant reservior cracked open losing all the coolant and then the engine started to overheat so I parked the car. I came back the next day with 10 gallons of water and poured it into the reservoir, started up the car and drove 10 miles home with one eye on the temperature gage and had to stop and fill up the car one time with more water.

So I ordered part number 1711 7573 781 Coolant Expansion tank. I also ordered a new coolant level sensor 1711 7 506 601 and when the parts came, I went to work. I had to do the following to remove and replace the parts...

1. Remove the air intake, and air filter box, and the corrogated plastic air intake tubes with the mass air flow sensor.
2. Remove the upper radiator hose that has two fitting connected into the radiator (large) and into the coolant reservoir (small).
3. Remove the mid level hose connected into the reservior.
4. Pop the clip on the bottom left of the reservoir and gently pull up on the reservior and it will dislodge from the two O-rings on the bottom. When the reservoir is disloged, be careful not to pull up too high because the coolant level sensor wire is still connected to the reservoir. You have your choice to disconnect the wire, or remove the sensor from the reservoir to free the reservoir.
5. Remove the coolant reservoir.

At this point, when I pulled the reservoir, a bunch of pieces fell out of the bottom including springs, plastic and brass parts. That was a broken expansion tank thermostat. When that thermostat failed, coolant was not leaving the tank so the tank pressurized from incoming coolant to the point of failure. When I was sitting in traffic, I heard the reservoir pop like a balloon.

6. I ordered a new coolant reservoir thermostat Part # 1711 1 437 362

Also I noticed when I took the air intake system out of the car that the Air intake boot Part #1354 1 440 102 was ripped. Finally, I had solved the Bank 1 and Bank 2 too lean codes (that was a mystery for a long time). I also replaced that boot and no longer does that that error code appear from the service engine light.

7. I replaced the air intake boot first which was a much harder job than it should have been. The hose clamps are facing away and down. And that is the only way they can be mounted. Getting to them was hard and my back is still aching from it.

8. I removed all broken pieces of the thermostat out of the radiator, and installed the new thermostat.
9. I installed the new reservoir, and clipped in the bottom metal clip.
10. I installed the middle hose and clip.
11. I installed the upper radiator hose onto the reservior (small fitting) and into the radiator (large fitting).
12. I installed the air intake, air filter box, and air intake tubes.
12. Mixed BMW coolant 2 parts water, 1 part coolant (good to -20C) and refilled the coolant reservoir.
13. Turned the car on and turned on the thermostat to 90 degrees.
14. I kept filling the reservior. In all, I used 5 liters of 2:1 mix water/coolant ratio.
15. Opened the bleed screw on top of the upper radiator hose, watched for bubbles, when no bubbles were there, I closed it. Everything was topped off.

Voila, another successful fix. Took two days to get everything straight!

Hope this helps.