Hi Everyone!
This Started a week ago while waiting for Gas ... Steam/Smoke under the hood, engine temperature indicator normal... shut the engine off right away, opened the hood and i see the coolant Tank all wet... let it sit for 10mtes and drive off back home. Didn't drive the car for a week after Hurricane Sandy... Drove it yesterday fine until engine temperature gets warm (No overheat according to the gauge meter) and again leak/bleed from the tank while waiting at the red light ... Has anyone experienced this kind of situation? Thanks!

Here some Pics.
Sorry they are upside down I ll get different ones...

 

Often they overflow if
1) cap is bad
2) they are filled beyond the max level
other possibilites are much less likly...like a blown headgasket.

 

Check for leaks or hole puncture. The last time my coolant tank had a leak and steam came out of the hood, it turned out that the motor mount broke and caused the engine to lurch into the coolant tank and punch a hole into it.

 

The tanks themselves have been known to be a problem (if the crack then they leak)
If you have issues elsewhere the pressure has to go somewhere and the cap on the tank is well a pressure cap. up to its rating it seals .. over that it is ment to leak out.

Looking at your photos there does seem to be some serious gunk in your tank. ...Is that maybe oil ???
Is you oil milky / cloudy ?

 

forgot to mention that the coolant/antifreeze in the tank has a brown foammy color

 

Either seriouly neglected coolant/cooling system.....or a blown headgasket....maybe both...been changed lately? Max coolant life is about 36 months.....mini does NOT use longlife coolant....
How is the oil? Level ok? Any creamyness?

 

oil level low, didn t see any creamyness and have not changed coolant for the past 3 years.

 

That looks like oil in the 3rd pic to me....

 

agree - color doesn't bother me but the sludge does . . .

if the level in the tank has gone up ... that's bad. Cars don't MAKE coolant so the level can only go up (in the long term) if something else got in there

If your cap has crapped out you'd lose the seal and could be seeing overflow simply because the system isn't holding pressure - with no pressure being held or too little the system can boil earlier.

I've replaced a number of GEN1 S overflow tanks. The early ones were identified as a bad design and the newer ones were supposed to be better .... I still see them leak quite regularly



this one was leaking from the seam on the back side .... look for signs of burned off coolant on the heat shield under the tank.

 

Time to change coolant. Coolant, like any liquid or matter expands w/ heat. Since it's a pressurized system, evaporation is supposed to be limited. The cap relieves pressure beyond 16psi. The 2pc tank splits over time. It's got a rubber gasket embedded at the seams. Only use distilled water/coolant mix. Never use tap or you risk sedimentation & corrosion. Let's not talk about serious matters like headgaskets here.

 

I got a 04 s and my tank was leaking. Pretty slow at first so i put it off and topped it off about once a month. Until i had diluted my antifreeze too much and it started boiling all the time i didnt notice until my wife and i were getting ready to go into the movies and sitting in the car we heard a boom followed by water hitting the ground. The expansion tank blowed apart at the seam. It wasnt hot because the car runs at like 225 or so. And water boils at 210.

 

The car shouldnt really be running at 225...thats when the high speed fan comes on. While cruising my R53's coolant never even gets into the 200s. Water boils at 212 btw (actually thats at atmospheric pressure, so in reality, thanks to our pressurized coolant systems the boiling point has been raised. To what? I don't know but I bet someone does.)

 

+1 on what weasel said.
Try checking if your silent 1st stage fan is working when you turn on your A/C. If it's the noisy fan that gets triggered, chances are you've a busted 1st stage resistor.
You may opt to follow the resistor mod many have done or Blwn's simple fix on post16 here:
https://www.northamericanmotoring.co...-resistor.html

 

Last I knew, the 1st stage fan comes on at 221* and 2nd stage at 234*. Under pressure and mixed it does not "boil".

 

My 1st stage fan comes on at about 220 and 2nd stage on at about 230 so my statement was just based off a rough estimate using these. I know it will vary from car to car but 248 just sounds scary hot to me.

 

Thanks to everyone for their opinions about this thread
I see that the last few posts have "nothing to do" with it... Fellas please i only posted this thread so the non technical person is able to get an idea if he gets in the the same situation. Personally I will problaby junk this Mini and will never ever buy a Mini Cooper S in my life ...and I owe 2 of them R50 & R53.

P.S. Whoever wants to get back to the original problem to help others is welcome...
I'm out.
Peace everyone!

 

@ sumbitweasel. You got me on the 212 however when you have a coolant leak it can not maintain the proper pressure on the system and i suppose i run my Mini pretty hard and like in southern Arkansas it got up to 117 with 85% humidity back in 2011 so my high speed fan stays on six months out the year.

 

Sorry about the thread highjack. I have a bit of the ADHD sometimes BACK ON TOPIC BOYS.

 

OK "djmuka" I will bite .
You posted a question and all those that are posting are trying to help (without seeing first hand and) ask needed questions ... that raises discussion
As I read it there, are some good tips and things to look at, perhaps even the cause.
Tank issues, cap issues, leak , headgasket and a very insightful discussion on fans and kick in times.
Their last couple of posts may very well be exactly your issue (well lets say your issue with the car)

That is what we do here - try to help..

So here still on topic... Maybe you need to pressure test the system .. That could help locate the leak source for you.
A temp probe and seeing when the different fans come on would answer if those are working (correctly)


Or "junk" this one. I will make you an offer if you want.
Get rid of the both that you "owe" ???

Peace

 

Yeah.....failure to matain you cooling system gets very $$$.
folks will go out of their way NOT to go a couple hundred miles over on an oil change....but often forget and neglect the cooling system....corrosion sets in....if lucky, only plugs the heater core, if not lucky, causes a headgasket failure or worse.
Coolant system mantance is not rocket science, but it does have to be done.
The fact these cars have an iron block and alloy head means it is even more important!
Good luck....but a headgasket and a cooling system plush should not be nearly enogh to junk a car!!
If it resulted from a crack....it might....
But user error due to lack of scheduled mantaince..how can you complain about a manufacturer?
at the very least, the car needs a person to look at it..might need a $15 part (cap), or a $6500 motor at worst.....and diganosing by internet will only get you blood preasure up if you do not have the skills to get a good look.

 

What is a gauge meter ? If you are referring to the OEM temp gauge on the dash it registers only three positions in the MINI not "temperature"....

At the bottom when engine has not been running, operating temp when in the middle, and the "OH ****" position "I just blew my headgasket."

It is not a gauge and should not be confused as such. Typically speaking anyone who has driven their MINI even a short distance while the indicator was at the "O-S" position needed major repairs afterwards. Somtimes not always....


Your original issue as stated was overheating while at idle wating for fuel pump access which blew out the reservoir cap or so it appears.

That condition can be caused by a multitude of issues including but not limted to: Proper Coolant used during it's use, maintenance, fluid level, integrity of the cap and tank, coolant hoses, coolant clamps, thermostat, thermostat gasket, radiator, waterpump, waterpump gasket, headgasket condition, a few other things I may have not mentioned AND....PROPER AIR FLOW THRU THE Radiator via the Two stage (temp) cooling fan !

The fact that you were not able to connect the dots on the aforementioned posts you deemed to be "off topic" is only shadowed by your ignorace to perform a a search function on your present quandry.

And if your thread was some sort of half *** attempt to conduct reasearch for a class action suit against MINI for this issue, then state your business straight away and instead of some clandestine attempt to extract data from good people who are actually looking to help you out.

Yes, there are litterly hundreds of posts on this very topic here IF you would just take the time to look.....

 

Has anyone found the solution to this problem? My 03 S is doing the exact same thing! I'm very mechanically inclined and I have no clue as to what's going on. Overflow tank ruptured a week ago so I replaced with oem tank for the time being. I proceeded to bleed the system and check for leaks. None where found and I assumed I got all of the air out. I start driving for a while and temp gauge reads normal, fans come on no issues. As soon as I park and turn car off fan kicks on and cooling system starts to boil. I then removed thermostat and bled the system again. I live in Vegas so running with no thermostat is def not an issue and it is safe it just takes longer to get to operating temps in colder climates. Again the same issue, fans kicks on and coolant starts to boil over. Checked my compression today and got 152(1),148(2), 150(3), 150(4) which I think is awesome for having 134k. I also vacuum bled/filled the system yesterday and its still doing it! Could there still be air trapped in there? I assume when the water pump fails its more to due with leaks than actual mechanical damage? Heater works fine so I think theres not enough air/gunk trapped there to cause an issue. I'm stumped! Sorry to thread jack

 

That does sound odd. I forget the procedure but there is a way to get into the OBD computer and have it display actual coolant temp. Unless you have a scangauge, then its easy. You really need to see the temperature in your system to figure out what's going on. The dummy gauge has a 50+ degree deadband where it sits in the center.

Just running through checks with bleeding the system... there are 2 bleed valves on the MCS. One on the upper radiator hose and another down by the thermostat that needs a socket and extension to get to.

The water pump usually fails when the gears driving it off the supercharger are destroyed when the oil eventually leaks out. It doesn't seem like this is your issue.

For coolant to boil when you turn the car off, it seems like you're running too hot to begin with plus losing pressure in the system.

I had a blown headgasket in my project car and it still showed full compression in all cylinders. I couldn't get a good bleed on that cooling system either. I finally figured out what was going on when it sat for a few months and my oil level was over-full

 

FWIW, I was constantly seeing overflow from the reservoir on TRACKRAT when instructing at DE's, even though indicated temp. was normal. Changed reservoirs and caps a couple of times...No help. I finally switched to a Canton aluminum reservoir and a STANT 30 lb. cap. No problems, no overflow, no high temps. Have found that it's important to keep the level in the reservoir only about 1 inch off the bottom. Having it too full will just aggrevate the problem. I dare say that, if you were to survey anyone running a FORGE or CANTON reservoir will have no overflow problems.

 

Where did you buy the aluminum coolant tank?

I'm looking to replace my coolant tank as well, and it has signs of leaking too. I want to get rid of it before something happens.