paran

First post but I've been reading and learning a lot from you guys so I thought I would post how this repair went today.

I have a 2005 545i SMG Sport with 99,000 miles.

Bought a Behr 8MA 376 789-731 or 17137542986 Expansion Tank from FCP Auto Parts 877-634-0063 for $41.27 delivered. Exact replacement for the original BMW unit down to the wording on the housing. The inner float assembly is loose vs contained as in the OEM BMW unit.

Supplies Used:

Pentosin Pentifrost NF
Crystal Springs Distilled water
Best Nitrile 8mil disposable gloves.
Oversized kitchen baster
Pyrex 4 cup measuring cup.
Solarforce L2P Cree flashlight
3 spring loaded clamps with protective covers.
Torx head socket and 3/8" wrench

Procedure.

1. Place a clamp on each the 3 hoses some distance from the connector so that coolant drain from the hose can be minimized. Check the pliabilty of your hoses at this time; no cracking should be seen in them. (3 minutes)

1. Removed coolant cap and began sucking the coolant out with the baster and attached plastic hose to reach all of the coolant in the tank and placed in the pyrex cup. Drained into an old oil 5 quart carton. Took about 15 minutes.

2. The three coolant hoses each have a wire clip holding the hose connector to the tank connector. The clips are not secured with a lot of force. I used my finger to pull up on the them to release (about 1/4") but a small flat head screwdriver could be used. Don't apply much pulling force as the clip should remain a part of the connector and not be pulled free of it. (about 3 minutes total)

3. Firnly grab onto one of the two hose connectors and pull straight back with a very slight wiggling/rocking motion. They're secured pretty tight so you'll need to pull straight back with some force. Watch the backside of your hand as the connector releases so you don't bang into something sharp. (3 minutes)

4. Release the other top hose in the same manner as above. (3 minutes)

5. There are two torq screws holding the tank in place. Unscrew both of these. They are plainly visible and easy to reach. (3 minutes)

6. Now lift up on the tank about 2 inches and release the electrical connector on the underside of the tank. Do this by grabbing onto the connector and squezzing it; you'll feel the connector tab release and pull it off. (3 minutes)

7. Now the lowest hose needs to be release so pull the tank up about 6 inches and while holding the tank body against your stomach, pull the hose connector off as in Step 3. There is going to be some coolant left in the hose and/or tank. I spreadout/draped an old t-shirt under the tank area when releasing this final hose and it prevented the coolant from splashing all over the engine area. Turn the tank so that this bottom opening is now facing up (keep it in this position) so that any further coolant doesn't leak out. (5 minutes)

8. The tank is now free from the car.

9. Replace in reverse order making sure that hose connector fully seats against the tank connector and compress each wire clip into place. This assures that the connector is seated properly. (20 minutes)

10. Make sure that the spring clamps are removed from the hoses.

11. Now, turn the ignition switch to "on" (don't start the car yet) and put the heat temperature setting to max while the fan speed is set to low.

12. Now begin adding fluid (50:50 mix) to the reservoir until its full.

13. Now start the car with the cap off and let it idle for 1 minute.

14. Turn off the car and add fluid if necessary.

15. Put coolant cap on tightly (arrows should align on cap & body) and restart car until it reaches full temp while idling.

16. Let the car cool and then check fluid level once more. Add if necessary.

Notes:

I removed 2.2 quarts of old fluid from the tank and hoses. So if you have fluid in the tank, and you don't siphon it out in some manner, you're going to have a mess on the garage floor and engine compartment to clean up. Take the time to empty the tank as much as possible prior to removal. It's a time saver.

My cree flashlight is small and super bright making it easy to check my connections

I placed several sheets of old cardboard under the general area of the tank on the garage floor.

I also used a large plastic plant pot drip tray to catch loose fluid. It's low and 18" wide so the car doesn't need to be jacked up.

I'm a low level, weekend, car maintenance guy; so anybody can do this job if they take their time and study the situation beforehand.

I used Pentosin Pentifrost NF Blue concentrated coolant and mixed 50:50 with Crystal Springs distilled water from the grocery store. Added coolant to the tank with pyrex cup

westsidebalto

Good writeup, thank you. Most of your tips were key to not making a huge mess.

Removal and installation was easy, but now I think at least one of the top hose connectors is leaking. I tried to reseat it, but I think I'm going to have to let it dry out before I can fully assess it.

paran

I'm glad it was of some help.

Just make sure that the hose connector is fully seated and that the clip is also fully seated. Wipe up around all of your connectors until dry and then put a bright flashlight to the suspected area of leakage with the car running at full temp.

Better to use the flashlight it a darkened garage as that can really focus the light where you want it to be. You can also wrap the hose fitting in a paper towel and see if there is remnant coolant. If its leaking, the paper towel will absorb it and show very quickly if that's the case.