Expansion tank failure

[jnwright71]

Hi All,

I'm a newbie to the Z4 and forum.

I picked up a lovely Z4 2.5si on Saturday. It is SORN'ed so I took it to the local MOT centre on my way home (pre-booked of course) and all was going well until the coolant expansion tank failed and sprayed hot coolant everywhere - not a great start as I had owned the car for only 1 hour.

So having had the car towed home, I set about finding a new expansion tank. No one had one and most referred me back to BMW as the part is dealer supply only. However on Monday I had some success and found that a standard E46 tank manufactured by Meyle is an exact equivalent, although Meyle themselves didn't know it !!

Thus for anyone who is interested, the BMW part no. for the expansion tank on my car (2.5 si 2007) is 17117573751 and the equivalent Meyle part number is 3142230000. Please note that Meyle state their part is only an equivalent to BMW part no. 17117573781 3 series (E46), X3 and X5), but I have fitted it, bled the system and run the car and all is good.

For anyone else needing to attempt this job, a simple overview of the stages is as follows (no photos, sorry);

- Remove plastic cover that sits over the radiator
- Remove the under engine drip tray
- Disconnect the battery (not entirely necessary, but some electrical connectors need to be undone)
- Drain the balance of the coolant by removing the blue drain screw at the base of the expansion tank
- Remove the airbox
- Disconnect all hoses by using a small screwdriver to open the spring clips and simply pull off
- Remove the level sensor from the base of the expansion tank (grey) by twisting through 90 degrees
- Open the spring clip that tolds the expansion tank onto bracket base
- Remove the tank by pushing / pulling upwards (tip - the tank is likely to be 'stuck', so from under the car tap the base of the tank either side using something like a spanner and rubber mallet - just don't hit it too hard)
- When loose, remove the tank by gently levering the radiator towards the front of the car to create enough space
- Insert the new tank in the same manner a removal
- Align the tank with the bracket base, ensuring that the upper retaining lug sits into the recess on the bracket
- Lightly lubricate the openings / connection outlets on the tank with Fresh coolant, silicone lube, light grease etc
- Press the tank down onto the bracke base (there is an o ring in the base of the tank). Tip - get a friend etc to push down on the top of the tank whilst pushing up on the base of he bracke from below the car
- Close the spring clip on the base of the bracket and reconnect all the hoses ( and close the clips). Re-fit the level sensor.
- Add fresh BMW supplied coolant and bleed the system as per these instructions http://www.zroadster.net/forum/viewtopic.php?f=5&t=39308&p=365362

Hope this helps someone else as the job is easy, it just takes time and patience.


Thanks, James

 

[Dale_B]

Nice little right up there James

Unfortunate you had this trouble so soon into ownership, least it's now sorted

 

[Dale_B]

Welcome to the forum BTW, get some pics up in the newbie section when you get a chance

 

[jnwright71]

Thanks, Dale.

Not the best start, but I did get the car for a good price, so there is a little on the budget to cope with this and tidy up some of the other small issues.

Will post some pictures when I can get the coolant, grease etc off the paintwork and things cleaned up to make it presentable.

Cheers.

 

[Leon.]

I have just done this for a friend who bought my car.

The OP's write up is very good - thank you - and the key is time and patience.

The most challenging parts were (1) finding the leak and (2) getting the tank out.

(1) The only way to be certain you know where the leak is coming from is to remove the undertray and get under the car with it running at full temp and it should be obvious if you keep drying it all down. Then buy your parts ( I learnt this by experience thinking it was the hose coming from the bottom of the tank )

(2) This is probably difficult as there are two O-ring connections at the bottom, so double friction. I found by using the chassis near the top of the tank to leverage off, I could prise the RHS of the tank with my fingers and this gave enough movement for the left side to give way.

Good luck. HTH.