Hello all. I have a strange issue w/my 2003 Mini.

My problem is that the coolant is slowly disappearing w/no apparent leak. Two weekends ago the cooling fan came on for the first time ever, I checked the coolant tank and it was bone dry. I refilled w/water and coolant and went on my way.

This weekend, same thing happened - fan came on and tank bone dry.

I haven't seen any puddling in my garage or anywhere else where I park. So the question is that where did the coolant go? I'm guessing this is a problem that needs to be looked at by a mechanic. My ability for self-help is limited with these types of things.

Thanks.

 

I had the same thing happening. My Mechanic replaced the thermostat and the thermostat housing. He said a leak there is common.

 

It could also be the water pump leaking. My 2007 developed a leak there, and no coolant puddles were spotted on my parking pad either. I had no idea a leak had started until I took the MINI in for it's 15,000 mile oil change and the dealership told me.

 

Had the same issue with my 2006 as well. Never did see a puddle or anything.

 

Check your coolant tank also....they thend to leak around the seam...and leave a whitish residue....thermostat housing leaks are common too...also as said earlier, check the weap-hole on you water pump. It seems safe to assume you have not smelled coolant? The preassure cap can go bad also...if you have your orgional you probably are overdue for a replacement.
I would also check you oil...if it looks normal...A-OK. If it looks creamy.....post back asap and you shoul talk to a mechanic ASAP.

 

A coolant tank leak at the seam is common for the 2003 vintage Minis. Many times you do not see any coolant on the ground because it evaporates in the engine compartment. Look for white residue around the middle seam of the coolant tank or white drip marks down the side of the tank.
The thermostat housing leak is more common with the 2006 vintage Minis. Again, many people do not see coolant on the ground because it evaporates in the engine compartment. When my thermostat housing leaked, I would see little puddles on the garage floor after the car sat overnight but no visable leak when running. If leaking, you should see white residue or coolant puddled near the housing.

 

Thanks for the info. Oil looks fine - I had a couple different people I trust with these things look at the oil.

looks like i'll be going to the mechanic soon and hoping it is only the thermostat issue. any idea how much that type of job runs these days?

 

Since you have a 2003 Mini, I would be a little surprised if it is a leaking thermostat housing. I would suspect a leaking coolant tank. The coolant tank is a very easy do it yourself job, if you want to do it. Otherwise, less than a 30 minute job for a mechanic. The tank cost about $40 from someplace such as Mini Mania.

If the thermostat housing, the housing is about $40 and the thermostat+gasket is about $40. It is a little more complicated to replace. I had mine done under warranty and the dealership did not specify the amount of labor, I would suspect you would be charged for 2 hours which should include a pressure test.

 

Also if the tank was totaly dry, the coolant system should be bleed....a standard part of most cooling system fixes.

 

Over the past 5 months, I have had to top off my coolant twice (BMW OEM and mixed 50/50 with distilled water), when the engine was cold.

Today for my one year maintenance, I told the S.A., and they did a pressure test. It turned out the thermostat was leaking. However, they replaced the thermostat, bled the system but did not replace the thermostat housing. Should they have replaced the housing as well? The reason I am asking is I just drove home from my friend's house (roughly a 15 mile drive), and the coolant level it back at the minimum level. When I left the dealership this afternoon, the coolant level was between min. and max. I will check again, once the engine is cold.

 

The thermostat housing/thermostat leak is common of Gen1 MINI's...mostly the gasket on the thermostat.....Since Gen2 are a totally different design...with a different Motor....most of the advise in this thread will not be of much help IMO. Good to see it was fixed for ya!! And you are Very smart to have been topping it off with the proper coolant!!

 

Thanks ZippyNH! I have to ask you what might be a stupid question. When the car reaches operating temperature, should the coolant level decrease, due to the coolant being in the radiator and then come back up once the engine has cooled?

 

As long as there are no air bubbles to compress in the coolant system....the opposite.....that is why the hot fill lines on containers are higher...the hot fluid expands.
During normal operation....the radiator and hoses are full of fluid....it gets hot, and will expand into the expansion tank.....then when the car cools...it will be sucked back into the cooling system from the tank. The secondary benefit of the expansion tank is that it holds a bit of extra fluid to make up for small leaks, or any evaporation that occurs in the system, such as from the tank itself.

 

Zippy is right, but note that since they opened the system, your lower coolant level could be caused by an air bubble getting worked out during the drive.

 

Thanks for dropping the knowledge on me. I just want to reiterate this site is awesome, and I don't know what I would do without the knowledgable members of NAM.

The reason I have been asking so many questions about the coolant is when I drove back from the stealer (roughly 20 miles), the coolant level had actually decreased. I kept an eye on it last night, and when I checked again this morning after letting the car sit over night, the actual coolant level was slightly below 1cm below the minimum line. I went to the basement and picked up my mixed batch of BMW coolant and distilled water, and I filled it up to half way between minimum and maximum. I went and ran some errands, and in the parking lot, I popped the hood, and the coolant was at the maximum level. I thought this was normal, since the coolant expands when it gets hot. About an hour after I got home and the car was sitting, I popped the hood again, and to surprise the coolant level was about 1cm below the level where I had filled it this morning. At this point I was heart broken knowing something must be wrong my with car, so I went and grabbed my jug of coolant once more. I opened the coolant tank slowly, and while I was was opening it, there was a pressurized noise that came out, like it was releasing gas, and the coolant level actually came back up. I just checked again, and now the level is smack dab at where I filled it this morning. I am going to make another appointment at my dealership for next weekend, but do you think the levels fluctuating was caused by an air bubble? The strange thing is when I opened the coolant tank this morning, it did not make any pressurized noise.

 

I just started having the same problem. Additionally, when I'm idling, the coolant indicator light comes on. But when I'm driving, the indicator goes off. I also noticed that when idling, the AC doesn't work very well too until I start moving.

 

There's another coolant inlet(#4) on the block behind the SC that has a plate with an o-ring which can seep a good amount of coolant over time if the seal fails.

 

what is SC?

 

Sc=supercharger