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

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.

That thermostat down at the bottom of the tank is only for the atf cooler. It would not have caused your expansion tank to crack.
Your expansion tank cracked because it is plastic.

Sent from my SGH-i917 using Board Express

Do you need any special tools for this DIY?

Oddly enough, I did this same coolant tank and intake boot replacement at the same time on my 3.0. No special tools were necessary. The tank takes some wiggling and maneuvering to get out and in though.

One part I would add at this point would be a new cap for the tank. For the $7 it's worth changing it out at the same time. They do sort of wear out.

No special tools needed! Car runs great!

Just wanted to say many thanks for the DIY! Just replaced my old cracked one today with parts bought from the stealer nearby lol. No more leaks.

Congrats on the successful fix, I did the same expansion tank fix about 3 month ago or so. Only difference in my case was, I had to change part number 12 shown in ur diagram because when the expansion tank thermostat disintegrated;half of it stayed in there. During the process of removing it, the 12 part started to fall apart literally it was so brittle... So the one couple hr job became 4 day because I had to order the part and wait til I get it. At the end, it felt good driving a car that has one less thing that leaks lol....

Inspect other cooling components while you're at it. I'm all about preventative maintennace so I wont be stranded somewhere remoted at the most inconvenient time. So if you X is about 100K mi or more, the OE cooling system is a ticking time bomb.

How did you get the transmission thermostat out? I had the same issue. It broke when pulling out the tank and now half of it is in the bottom.

For anyone doing this job, I recommend ordering a new transmission thermostat with the tank. I cannot image a way to get the tank out without breaking it. The plastic is old and brittle.

Thermostat is just pushed in and held in by the O-rings much like the hoses. I am gonna lube it up just in case I need to take it back apart.

Got a new thermostat from Napa for $86, expensive but they were able to special order it and have it to me in less than 24 hours on a weekend. If it was Monday I would have ordered it from Oembimmerparts and had it overnighted.

This exactly what has happened today to me on the same model. I am having a heck of a time getting the mounting plate off the radiator. Do I have to remove the radiator as well? Thanks for any help.

No you dont need to remove the mounting plate off... I think there are one or 2 screws and a clip that holds the bracket to the radiator. Once u have all the screw and clips removed, push the bracket off the radiator (towards the engine) and not up.. Check the diagram to see how the bracket connects to the radiator.
Good luck

Thank you. I found the two screws and clip. I suppose I also have to remove the transmission cooler?

On the e46 with the same engine you would. So it makes sense that you would have to detach it on the X. I would have replace the orings as well. They are around 5.00 each or so at the dealer and I think you need 3 total.

See post 35 and do what you feel is appropriate:
Issue with Behr Radiators - Page 2 - E46Fanatics

I assume you have an automatic.

Thank you. I got the BMW 5346 tool to help me remove the lines from the transmission cooler. The top line comes out with no issues using this tool. I am thinking wow this was the best $35 I've spent. I get under the car and put it on the bottom line. No such luck. It appears this hose connector isn't operating properly at all. I am afraid to use too much force because I don't want to damage it. Anybody have any experience with that? Thanks

Spray the collar where it mates with the line with silicone spray, then fit the tool and wiggle it around. Should release.

You are talking about the transmission cooler being detached from the mounting plate right? I just used a screw driver to pry a little then pull.

I am replacing my radiator right now on my e46. What started as a 4 hour job has turned into a marathon it seems. Some of my hoses would not come off and I have flatted orings in some of them. So I ordered new hoses instead of chasing down the orings. At least the dealer sells the transmission cooler orings.

You don't remove the lines. You detach the cooler from the mounting plate.

I am not sure what the BMW tool is for. You remove the cooler from the bracket... DO NOT Disconnect the hoses from the cooler, you could drain your ATF.. In the diagram below, you pull on clip 13 up and then pry with a long screw driver to remove it. The full assembly will come out at 12 (circled in red)

http://i1002.photobucket.com/albums/...psm2knbfvz.jpg

Thank you. I finally got the part in I was waiting for and am going to continue on this project today. Where exactly is #13 and what does it look like? I'm having a hard time finding that. Thanks for the help. I hope to post a recap of the problems I faced as a relatively inexperienced DIYer.

I got it. That was much easier than I made it.

good luck and enjoy the ride. My bmw was out of commission for a few days because of the disintegrated thermostat which was very inconvenient and unplanned :-).

got the coolant leak stopped. unfortunately a terrible leak apparently out of the transmission cooler occurred while driving it around the neighborhood. got the transmission failsafe message and it shut off. leaking black fluid like crazy. tow truck time. i hate automatic transmissions.

Oh man hopefully it's a busted line and that the truck shut off before you caused any damage. Good luck.

At least now you get to do a fluid and filter change now.

For me at least, I would not want that black fluid in my tranny. I know their are opposing views to this, but this my personal preference.

Don't give up on being a DIY'er. These experiences will add to you and you will get better. My e46 radiator change has turned into a mess, but I am on the rebound with the help of some more unplanned new parts being replaced.