30 replies to this topic

[Subsea]

I have a very annoying problem that has led me to join this site and air the problem . I bought my girlfriend an 03 reg cooper s with 150k miles on it. All was well for a couple of weeks and whilst doing a trip of 40 miles due to her work when she stopped she heard bubbling from the water bottle / header bottle and saw water dribbling out . Being a handy mechanic I decided without doing gas analysing test to change the head gasket as it had done 150k miles and did not know the history . Head gasket all changed and exactly the same !! So I changed the water pump and thermostat still exactly the same and I could find no fault with the other water pump anyway . The car has just done 70 miles and bubbles again when pulling to a stop and was topped up with another litre of water . The head surface was in good condition and block with no cracks anywhere especially from cylinder to waterway . Has anyone any ideas or experienced anything similar ? Would be so great full for any positive input ..Chris

[danie garry]

Water pump maybe? Is it over heating on the dial?

[Subsea]

No I have. Changed the water pump for new and the dial does not rise above normal ???

[KernowCooper]

Whats the flow through the Radiator like, could be not efficient in the hot weather due to age or build up of particules causing it to run hot, its either boiling the water hence the bubbling or there is a compression leak, I'd do a sniff test to rule out combustion gasses in the cooling syatem, then look at the radiator and back flow it. Does the cooling fan come on when its this hot?

[blackbelt1990]

Have you checked there is no air stuck in the system?

[Subsea]

Thanks for that .. I did suspect the radiator as it seemed to happen when the weather warmed up . I'm pretty sure it's not gases getting into the water there are no bubbles visible and took great care cleaning and inspecting the head and block . I once had a Cherokee 4 litre jeep that overheated early summer after buying it in the winter when I towed it . Turned out a third if the veins were blocked and I managed to clean them by uncrimping the plastic ends and passing some of that blue banding in through the lateral veins . The water pump being aluminium in a cast iron block had all but eroded away so I guess the previous owner had just pored rad weld in at some point only to raise it's ugly head as the weather warmed up . The mini is currently in Nottingham so can't check the flow just yet but do remember feeling the rad as the thermostat opened and only the left hand side felt hot . I did not hear the fan cut in whilst she was idling and also fitted an override switch just in case in slow traffic it needed a nudge . Without looking is the mini rad a sealed unit or can it come to bits ? I know I had problems with a small leak on the plastic hose moulding that bolts onto the top of the rad and ended up having to grind away the plastic walls that hold the nut in place so I could get a spanner on ! Great when the nuts and bolts are new but an 03 mini with rusted up ones just revolved cutting the plastic !

[Subsea]

Yes I have purged the system of any air and happy there are no air locks

[Subsea]

I am now pointing the finger at the rad !! Hmmmm where's Columbo or poirot when you need them eh ?

[Shep76S]

If you turn the air con on, one of the rad fans should turn on. That's the easiest way to check fan operation. The temp gauge always reads middle unless it is really over temp, then it goes to max in a matter of seconds. The gauge is not a true representation on temp.
There are a number of water bottle and pressure cap failures so it might be worth changing those, don't forget if you cannot pressurise the rad system the coolant will boil at 100 rather than say 120 deg.

[sledgehammer]

what is the rad / expansion cap like , is it leaking early letting the water boil ? edit ^^ beaten to it ^^

 

is it possible a hose has collapsed inside - but looks ok outside - so restricting flow somewhere ?

 

I would also flush thru a few more times - then put in a good mix of antifreeze/coolant

 

PS we are a mini classic site - but it don't really matter that much - we all like cars

Edited by sledgehammer, 27 July 2014 - 06:08 PM.

[Subsea]

Ah right I have joined a mini classic site and not the bmw nothing to do with the real mini !! Sorry guys !! But in my defence I have owned 3 minis at ones one a clubman and one an 850 that I drove from the midlands to the faslane submarine base in Scotland with not too many problems ! I was thinking of ordering a new cap as there can't be at many things left to change .. Suppose I will have to scan e bay for an old mini now to justify being on here lol

[Subsea]

And so far I am impressed with the helpful suggestions put forward by seasoned mini mechanics !!!

[KernowCooper]

Don't forget the Minis are toys for most of us, and were involved in mainstream day to day cars and cooling systems hanen't changed in basic operation so its common advice what ever the year, I'd be back flushing and checking the rad as you suspect.

[cal844]

These engines are like that, the engines pressurise the coolant... Something to do with crank case pressures 

[Badboytunes]

 Something to do with crank case pressures 

 

 

erm... I dont think that is correct at all. Crankcase pressure is not related to a presurised coolant system.......