Coolant leak

UK forum for general and technical discussion about the Z3 roadster
Post Reply
Patty
Joined: Thu 09 Feb, 2012 15:55
Posts: 38

  Z3 roadster 1.9i
Location: Wigton

Coolant leak

Post by Patty »

Hi, I've experienced this problem before but it occurred during a very cold winter period and cured itself once the temperature improved. I was advised on that occasion that the seal on the plastic water reservoir had probably shrunk allowing a slight leak, expending again when the temperature rose. I think this time the seal has had its day and needs replaced. Can anyone advise as to where this is a straight forward job involving draining down the coolant, removing the plastic housing on the top of the tank then being able to remove the tank to replace the seal between the tank and the radiator. Are there any hidden issues to look out for if you're going to attempt this job yourself.
henrycrun
Joined: Wed 18 Apr, 2007 19:48
Posts: 522

  Z3 roadster 1.9
Location: Ely

Re: Coolant leak

Post by henrycrun »

It can be done but IMO the whole Z3 radiator will have to be removed in order to take the expansion bottle off.
The radiator has just 2 quick release fixings on the top but it is not that obvious as to how they work.

I would be tempted to just bung in a bottle of K-Seal, but others will disagree.
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: Coolant leak

Post by Del »

I overhauled my 1.9 (M44 engine) cooling system recently. You need to take the radiator out. Assuming your radiator or expansion bottle has not sprung a leak on a seam, there are several rubber o-rings that could cause a leak:-

1 A small one on the top bleed screw.

2 Two small ones on the blue, drain plug at the bottom of the radiator.

3 The large oval one at the bottom of the bottle, where the bottle push-fits to the radiator.

4 A small one on a “swan-neck” at the top of the expansion bottle which faces inwards and is only visible when the bottle is separated from the radiator.

5 My radiator had a plastic “blank” at the bottom which also contained an o-ring which looked “suspect” on mine.

You can use generic o-rings for all but 3 and I would recommend filling the radiator with plain water and blocking the hose connections, to check for any leaks before refitting to the car.

To separate the expansion bottle from the radiator you need to remove the securing bracket at the top (two small torx screws) and prise the bottle from the bottom of the radiator – I had an assistant (my son) who pulled the bottle at the same time – it is only push-fit. :)
Patty
Joined: Thu 09 Feb, 2012 15:55
Posts: 38

  Z3 roadster 1.9i
Location: Wigton

Re: Coolant leak

Post by Patty »

Thanks for the response to my questions. It sounds like removing the radiator to access all of these O rings will be the best option, as you say getting the quick release fixings off without damaging them appears to be the first hurdle, any advice on achieving this?
Image
User avatar
Brian H
Joined: Tue 16 Dec, 2008 19:55
Posts: 2505

  Z3 roadster 3.0i

Re: Coolant leak

Post by Brian H »

The radiator clips on the front slam panel are easy to remove, use a flat bladed screwdriver and insert in to the small slot in front of the clip directly in front of the arrow, lever downwards and the clip will come free. The clip is a ratchet style clip therefore you may have to follow the process above a few times to get it to fully release, the clip will bend a little whilst being removed.

HTH
Jonco
Joined: Sat 04 Jun, 2011 07:24
Posts: 402

  Z3 roadster 1.9
Location: Cheshire

Re: Coolant leak

Post by Jonco »

Del wrote:............................prise the bottle from the bottom of the radiator – I had an assistant (my son) who pulled the bottle at the same time – it is only push-fit. :)
If it will not pull apart then try this http://www.zroadster.net/forum/viewtopi ... tion+tank- worked for me.
Patty
Joined: Thu 09 Feb, 2012 15:55
Posts: 38

  Z3 roadster 1.9i
Location: Wigton

Re: Coolant leak

Post by Patty »

Thanks for that advice Jonco, as you say easy when you know how, now to drain down, remove the hose pipes and temperature probe and withdraw the radiator, fingers crossed.
Image
User avatar
TitanTim
Joined: Mon 23 Jun, 2008 18:56
Posts: 5488

  Z3 roadster 1.9i
Location: Stafford

Re: Coolant leak

Post by TitanTim »

MIne did this when I had the Zed stored over the very cold winter of 2010 when I dipped below -20. When I pulled the Zed out in the spring there was a pool of coolant in the undertray under where the expansion bottle sits. Mopped it up, topped up and its never leaked since so haven't bothered with it.

Tim.
Image
2001 Z3 1.9 Roadster Sport - 2012 Z4 sDrive 2.0 M Sport
Patty
Joined: Thu 09 Feb, 2012 15:55
Posts: 38

  Z3 roadster 1.9i
Location: Wigton

Re: Coolant leak

Post by Patty »

Well that's it radiators out and expansion tank removed, off to the garage tomorrow to get either o rings/seals or a replacement tank. Came out not to bad, pity BMW mount hose jubilee clips in a position hard to get at from under the car and impossible to get at from above.
Thanks for everyone's help hopefully will go back together without any dramas.
Although I have not sent notice about going to Beamish I live about 60mile from Beamish just outside Carlisle so hopefully if its a good day I'll be there, look forward to meeting some fellow Z owners in the flesh.
Image
Trevsky
Joined: Tue 26 Jul, 2011 21:57
Posts: 140

  Z3 roadster 1.9
Location: Leeds

Re: Coolant leak

Post by Trevsky »

Try CarParts for less.co.uk. I did mine last year and got a Febi Bilstein Expansion Tank complete with seals for only £16.74 incl VAT delivered
User avatar
Nad
Joined: Tue 01 Oct, 2013 07:23
Posts: 34

  Z3 roadster 1.8 TU

Re: Coolant leak

Post by Nad »

Try K-Seal coolant additive, it worked for me :roflmao:
Nad
Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: Coolant leak

Post by Del »

Patty wrote:Came out not to bad
That might simply be the problem - the o-ring usually creates a tight seal making it quite a "tug" to get the parts apart.
Patty
Joined: Thu 09 Feb, 2012 15:55
Posts: 38

  Z3 roadster 1.9i
Location: Wigton

Re: Coolant leak

Post by Patty »

Called local BMW garage re expansion tank, was quoted £79.55 available this afternoon. Got to thinking this must be available locally, what do you know, Unipart had one in stock £19 including VAT. The BMW garage should be ashamed, bare faced highway robbery, suppose they've got to re coupe all the money they spend on their showrooms somehow but 4x the price!!!
Image
User avatar
BladeRunner919
Joined: Fri 17 Feb, 2012 20:18
Posts: 2225

  Z3 roadster 1.9

Re: Coolant leak

Post by BladeRunner919 »

You can get a whole radiator including expansion tank for £77 from carpartsforless - I'd be inclined to just swap the whole thing and sort it once and for all.
Post Reply