Coolant leak, common location/failure mode?

[Mr Whippy]

Hi everyone,

Yep, now I'm using my car occasionally vs every day it seems to have more problems than it used to... grrr.

So for the last year or so the coolant seems to go down a slight bit but I top it up and it's fine. I think I've put in about 250ml in the last 18 months.

But on Friday the light came on in the car, so I refilled it up to the top when cold (I'd just bobbed out for a local curry hehe, so it was cold any way). Since then I've done about 25 miles and now tonight the light has come on again and it seems to have turned into a bigger leak.

I had a look under the bonnet and there is coolant leaking off a pipe just under the VANOS area. It looks like the water pump sits up there, and a few plastic solid pipes run near there, with rubbers then running off those with bayonet type attachments.

It seems to be simply leaking from a bayonet connection? Is that a common problem? A common failure point?


It looks quite hard to get to though which could complicate matters, but mainly I'm just checking if this is a common problem for it to fail, and if it's an easy fix?


I'll think I'll be taking it to a garage for the fix unless it's literally a replacement pipe and a 30min DIY job to replace pipes up in that area...

This car this last month hehe... seems to be emptying my bank account nicely hehe.

Many thanks for any help!

Dave

 

[bcworkz]

The most common leakage point I hear of is from the bottom of the expansion tank, which is another sort of bayonet connection. Guilty by association I'd say, though I've not heard about the specific leak you are experiencing. I don't have extensive experience, so what I've observed or not doesn't mean a lot.

 

[foxy-stoat]

Post up a photo of the offending pipe/fitting.

Maybe just a coolant pipe needs to be changed.

 

[Mr Whippy]

Hi there,

Thanks for the feedback so far.

The pipe that looks like it's leaking is on here:

http://bmwfans.info/parts/catalog/E85/Roadster/Europe/Z4_3.0i-M54/RHD/N/2004/june/browse/radiator/cooling_system_water_hoses/

Pipe 1 at the sensor end.

The pipe is rubber and that slides over a plastic insert end piece which is then a 'quick release' fitting that clicks onto the thermostat housing, which is number 4 on this diagram.

http://bmwfans.info/parts/catalog/E85/Roadster/Europe/Z4_3.0i-M54/RHD/N/2004/june/browse/engine/waterpump_thermostat/


The leak *seems* to be coming from either the union from thermostat > pipe, Oooor, the rubber pipe sliding over the plastic end piece union (there is a non-removal steel brace around this join, maybe it gets weak over time?)



The worry might be that the thermostat housing is actually damaged/cracked (seems unlikely though), or the gasket between it and the water pump is leaking around the top half, letting water run down the thermostat housing and past the connections noted above, making it look like a leak there.


It's all very hard to see/get at due to the slam panel and plastic VANOS housing covering. I might have more luck coming from underneath to inspect but I'll have to get the car jacked up etc and remove the under-trays and so on... sigh.


Marginally tempted to just take it to BMW and let them do the service that is almost due, the belts on the engine and fix this water leak... £££ eek!

Dave

 

[bcworkz]

Hi Dave, sounds like you've got a good handle on things. Hope you get away without spending too much, time or money, which ever path you take.

I must be getting old, I find myself looking at repairs, thinking "I could fix that, but that's a lot of faffing about. I'm just going have my mechanic do it." I don't even have the disposable income where this sort of reasoning is acceptable.

 

[foxy-stoat]

Another member had the same issue and it was that pipe. Not too difficult to change

 

[Mr Whippy]

Hehe, BCW, I agree. It's a bugger to do these jobs sometimes, but sometimes they can go really smoothly and be nowhere near as bad as you imagine.

Main problem here is the coolant drop...

I'll probably just take the pipe off and bung the new one on as quickly as possible hehe... then top-up with 50:50 and re-bleed.

If anything else looks to need doing after that then I'll probably let a garage do it as it needs the belts changing too really as they are getting quite swishy wishy and noisy these days.


Foxy, that is really useful info, thanks. I'll start there then move on if the problem persists. The other pipe to the right hand side looks in perfect condition... weird but I guess the one to the left bears the biggest thermal loads and hot/cold cycling etc...

Hmm

Dave

 

[jimbo1958]

Another member had the same issue and it was that pipe. Not too difficult to change

That was me who got the hose from you foxy.
http://www.z4-forum.com/forum/viewtopic.php?f=3&t=49698
I also had to change the sensor o-seal as there was a slight weep.
Have details where to purchase if required Mr Whippy.

 

[foxy-stoat]

Another member had the same issue and it was that pipe. Not too difficult to change

That was me who got the hose from you foxy.
http://www.z4-forum.com/forum/viewtopic.php?f=3&t=49698
I also had to change the sensor o-seal as there was a slight weep.
Have details where to purchase if required Mr Whippy.

Arrr yeah, hope its all good now

 

[Mr Whippy]

Ah cool thanks for the heads up.

I have some spare coolant concentrate and have just ordered the pipe.


BMW have a swap-over on pipe part numbers for this bit in April 04, so pre 04/04 the part number is 17127514405, post 04/04 it's 17127535591

So I have the earlier design as I'm March 04 build, despite it being registered June 04 haha (what I used on the parts finder on line!)


I'll start with the easy bits and work on from there... if the sensor O-ring looks a bit dodgy I might just buy a new O-ring and save £££ buying the sensor too.

No point going over-kill on fixes if it doesn't need them.


PS, has anyone done the belts themselves? How easy it is? Looks like a tensioner to release the belt, then just wind the new one on and release the tensioner back against the belt?!


Cheers

Dave

 

[slick]

My moneys on the sensor "O" ring.....available only with the sensor from BMW but the sensor is cheap enough

 

[jimbo1958]

My moneys on the sensor "O" ring.....available only with the sensor from BMW but the sensor is cheap enough

Just bought an o-seal from here. Cured my leak.
Its the 8mm Inner Diameter x 14mm Outer Diameter x 3mm Thickness. Part No. OR8X3 http://www.bearingstation.co.uk/Products/O_Rings/Nitrile_O_Ring_Metric/1mm_-_24.99mm/OR8X3

Came in at £5.40 with fast delivery but there is a cheaper postage option.

 

[RJS-Z4]

I'll be doing the belts my self next month of the one after, I'll report back with how it goes. Looks fairly simple though, belt and tension, remove all, refit as it was, tighten up tensioner and away you go.

 

[Mr Whippy]

Might order an o-ring, saves spending money on a sensor that I don't need...

Is that deffo the right one Jimbo?

6mm thick from 8mm ID to 14mm OD, so a 3mm radius thickness?


I suppose I can remove my sensor and check pretty easily

Cheers

Dave

 

[jimbo1958]

Might order an o-ring, saves spending money on a sensor that I don't need...

Is that deffo the right one Jimbo?

6mm thick from 8mm ID to 14mm OD, so a 3mm radius thickness?


I suppose I can remove my sensor and check pretty easily

Cheers

Dave

Definitely the right one Dave......not a 3mm radius thickness......3mm diameter which gives you the 3mm+3mm+8mm =14mm OD.
A lot of money for one o-seal. I've got o-seal kits at work but nothing that came close to this though.

 

[srhutch]

Might be worth trying a local motor factors re the oring as they are fairly generic

 

[CarmadJames]

Hi

Assuming yours is pretty similar to my 2.5, the belts really were very simple to change. I did mine from underneath. With the tray already removed it literally took 5 minutes. I was impressed that this seemed so well designed.

Re the hoses on your thermostat housing:- It was very tight getting in to remove the thermostat housing and I hadn't taken the large black plastic panel off from over the rad when I first did it which it turns out would have given more points of access and enabled me to actually see what I was doing!

In my case it was all but impossible to remove the lower of the hoses from the thermostat housing as it was so solidly on and there wasn't enough room to get really a good grip on it. I ended up damaging the thermostat housing a bit, but as you know I was replacing that anyway. Hopefully you will have more luck.

Everything new with a bit of silicone lubricant was like a dream to put back together.

 

[RJS-Z4]

Well, that's cheered me up regarding the belts!

 

[slick]

My moneys on the sensor "O" ring.....available only with the sensor from BMW but the sensor is cheap enough

Just bought an o-seal from here. Cured my leak.
Its the 8mm Inner Diameter x 14mm Outer Diameter x 3mm Thickness. Part No. OR8X3 http://www.bearingstation.co.uk/Products/O_Rings/Nitrile_O_Ring_Metric/1mm_-_24.99mm/OR8X3

Came in at £5.40 with fast delivery but there is a cheaper postage option.

Worth the saving if you have time to wait for the post

 

[Mr Whippy]

Just ordered an o-ring now.

Gonna approach this job with all the parts to do the job on the left hose section. It's leaking somewhere down there so if I'm delving in I want to be able to get it all 100% in one sitting before moving on to other possible issues (if there are any)

Still not had a proper look at the leaking area specifically, it's a tight area to get to. I might have to go take a look this afternoon again and set the engine running. I'm guessing if it doesn't leak from a cold start that is good news as it says the thermostat is working right AND the leak must be post thermostat outlet

Dave