Afternoon chaps, it's been a while since I had any problems but a new bunch have occurred, while I must add the car runs great still but!
Whilst cleaning my engine bay one day I noticed (because if it's nice bright pink colour) my water resivoiur seems to overflow a little? I don't seem to be losing too much water but it's hard to tell really, I just noticed staining round the cap, it's never happened before but I need to get to the bottom of it!
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Water tank overflow
Water tank overflow
4.4 silver on chrome 22s
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X5-D-Sport
- Snr Member
- Posts: 1339
- Joined: Sun May 25, 2014 11:13 pm
Re: Water tank overflow
Several possible reasons for this....
Nicest first...
1.Contamination on mating surfaces of cap seal ring to sealing surface face of expansion bottle. Sometimes a precipitate chalky appearance on the parts - which is porus. Clean parts...possibly replace rad cap.
2.Cap sealing rubber perished... replace rad cap.
3.Thermostat jammed closed/partially closed and engine too hot causing pressure venting from cap. Replace Thermostat.
4.Head gasket failure causing coolant to be pressurised from compression gasses.
There may be tell-tale signs of oil film on coolant surface.
The head gasket failure can be easily remedied by a bottle of "Real-Steel" which will permanently fix the gasket (if the gas leak is minor), or strip engine & change head gasket.
How much coolant is leaking ?
Does the temp remain stable at instrument gauge ?
Is coolant level still good... hinting at a very minor leak ?
1st task is too change the Rad Cap, clean any debris from expansion bottle sealing surface...and see what happens...
Regards
Grant B
Nicest first...
1.Contamination on mating surfaces of cap seal ring to sealing surface face of expansion bottle. Sometimes a precipitate chalky appearance on the parts - which is porus. Clean parts...possibly replace rad cap.
2.Cap sealing rubber perished... replace rad cap.
3.Thermostat jammed closed/partially closed and engine too hot causing pressure venting from cap. Replace Thermostat.
4.Head gasket failure causing coolant to be pressurised from compression gasses.
There may be tell-tale signs of oil film on coolant surface.
The head gasket failure can be easily remedied by a bottle of "Real-Steel" which will permanently fix the gasket (if the gas leak is minor), or strip engine & change head gasket.
How much coolant is leaking ?
Does the temp remain stable at instrument gauge ?
Is coolant level still good... hinting at a very minor leak ?
1st task is too change the Rad Cap, clean any debris from expansion bottle sealing surface...and see what happens...
Regards
Grant B
Last edited by X5-D-Sport on Sun May 03, 2015 6:17 pm, edited 1 time in total.
Re: Water tank overflow
Thanks for the reply, I have checked oil and water as I thought it could be the head! But water is 100% free of oil and oil is pure oil, the cap rubber seal looks ok, the car temp gauge never goes higher than half gauge, I have a minor oil leak somewhere and I did over fill with oil once and I had a "oil pressure fault" warning on the bc for a few minutes one day. The over flow water problem seem to stem on the same trip I did that, but that was a 1000 miles ago and oil levels are perfect now and have been for ages????? 
4.4 silver on chrome 22s
-
X5-D-Sport
- Snr Member
- Posts: 1339
- Joined: Sun May 25, 2014 11:13 pm
Re: Water tank overflow
Well... a radiator cap generally only ever gets changed when it leaks...
Maybe its leaking....
Its the cheapest fix and the 1st thing Id change if I were you...
Change it and see what happens.
Maybe its leaking....
Its the cheapest fix and the 1st thing Id change if I were you...
Change it and see what happens.
Re: Water tank overflow
The temperature gauge should be in the middle for a certain temperature range, if you want to see exactly what the temperature is, you should be able to unlock the OBC. This link worked for my 02 http://www.bimmerforums.com/forum/showt ... uter-(OBC)