For the past few weeks I have been noticing that a small puddle has been forming on my driveway. Light green liquid which I presume is the radiator fluid. I dont have a clue where it has been coming from. It looks like the leak is near the overflow bottle, but I cant see any of the liquid on the heat shield which is directly below it. The tank is only about 2/3 full, so its not draining the entire thing. Any ideas?

 

Does the fluid feel oily or does it feel like dish water? Both the power steering fluid and the coolant are green, the power steering fluid is oily. I'd feel for a leak around the thermostat housing for coolant leaks, seems to be a common problem.I'd also look for a leak around the PS pump.

 

Dealer just replaced my thermostat gasket due to a similar leak. I would get a puddle of coolant under the car during the night when the car was sitting in the garage. It did not seem to leak while driving. The coolant is green but looked more blue/purple when on my garage floor. My car had 22000 miles when it started to leak. A leak at the therostat is very common.

 

Ok next time it leaks ill check. The waiting game begins.

 

So it leaked today, again. I touched the puddle and it was sorta like water, but after rubbing it in my palm for a while it felt slightly oily. I presume it is the radiator coolant. The tank which is directly above the leak has been getting lower. The car has only done 17,000 km so it hasn't had much wear and tear. Ill top the car back up, but I still cant find where it is leaking from.

 

The reservoir needs to be replaced. I've had 3 go bad in 6 years.

 

And why didn't they pick this up in its servicing a month or so ago haha. So ill go to the mini dealer tomorrow and book it in. Oh joy. Thanks everybody! Hopefully my problems will be solved.

 

It could be the reservoir or therostat housing/gasket. The reservoir usually leaks at the seam and you can see white residue where it leaks down the side. It is hard to see if the thermostat is leaking other than a puddle under the car. Mine started leaking at 21000 miles. It started as a slow leak, few drops on the floor, and after a few weeks was about 3-4 oz a night. A leaking thermostat is a very common problem with 15000 - 25000 miles on a car. My thermostat did not seem to leak while driving (when engine was hot).

 

Not only can the gasket leak, but there have been cases of the thermostat housing cracking also, and causing the leak. It is plastic, not metal.

I replaced the reservoir, thermostat housing, gasket and thermostat in our 05 MCS at about 70k miles after getting tired of the small drips and the gasket was a dried up flaky mess. Under $70 for the gasket, housing and thermostat from the dealer for those out of warranty and willing to do it themselves.

 

I have also had to have the thermostat & housing replaced, but that would cause a leak dripping off the left underside of the transmission. 07BPB's leak is under the reservoir, hence that is the culprit.

 

So i ended up getting distracted and didnt go to the dealer.

I put the car up on the ramps today and crawled underneath. I saw some of the fluid on some black tubes about midway between the coolant bottle and the bottom of the car. Next I found some more on the left hand side of the black metal skid pan near the power steering fan. Also found some of this liquid on the silver round power steering pump thing (real technical terms there ) I am positive it is the radiator fluid, but I can not find the culprit of the leak still. I guess now I WILL go to the dealer

 

I'm still voting for a bad reservoir. You would actually witness dripping (while the car is running) if it were a bad thermostat housing.

 

If there is no evidence (white residue) of leaking at the reservoir seam, I would still guess the thermostat housing. My housing did not leak when the engine was running, only when the engine was off and cool for some time such as over-night. Good luck at the dealer.

 

Today, i have been to the BMW service for my car for inspection 1. They found that my thermostat is leaking. The man of the sevice said that they need to change the thermostat. the cost is to high about 120euro = 190$ include installation. Why it so expensive this part

 

The leaking have strated from 20000miles .

 

Nobody????

 

Profit. They have to pay for the new part, labour and they are a business who wants to make money.

 

I just had to replace my thermostat a few days ago. The stat had stuck closed and steam went everywhere. I was lucky and no engine damage.

I picked up a new stat & gasket at the dealer and installed it myself. The installation went pretty good. Once the cold air intake was removed I could see where the stat is located. On the right end of the block. I think three bolts hold the housing to the block. Two hoses are connected to the stat housing. There are a few other cables in the area that have to be moved aside to get to the bolts holding the stat housing but not bad to work with. Once the stat housing was out it is easy to change the stat and gasket. The stat will only go in one way so you can not make a mistake. Now put it all back as it come out. Refill the collant and bleed off the air from the bleed screw in the large hose in front of the engine and just behind the radiator. Start the engine - turn the heater on max - let it reach temp than shut it off and let it cool. Turn heater off. Recheck the level in the overflow tank making sure it is not over filled. Should be back in business now.

Just a quick write up as I recall. Hope this helps if you are willing to change it yourself. By the way I think the stat and gasket was about $35 to $40 US. Good Luck.

 

Finally got the time to get it looked at. It was to the point where I was filling up my reservoir bottle every 4 days. The thermostat had gone berserk and seized up. Didnt pay a cent to get it fixed, good ol warranty, and the people at the dealer like me

 

My 2003 Cooper's radiator sprung a leak, at the seam between the plastic tank and the radiator fins, just below the top hose. I had about 60K when it happened. Replace the entire radiator, it happens.

retroom

 

Yesterday I found some cooling fluid on the heat shield under the radiator expansion tank as well as a 1 inch puddle on the floor. Checked the level in the expansion tank finding itl a bit low. After removing the expansion tank I found the seam on the back of the tank had pulled apart. Replaced the tank and all is fine again. 2003 MCS just under 90,000 miles.

 

My coolant leak started about three weeks ago. Obviously from the T-stat area. 27K miles. Fixed by dealer (Mini of Nashville) no fuss, no muss, so far, great dealership. They gave me an 08 clubman s as a loaner. Surely not looking a loaner gift horse in the mouth, but it really made me appreciate my 06 MCS. While there, they heard my "click from the front axle" and put a new front axle on order. Hope that fixes that... will see.

YD

 

I think I'll have to replace the reservoir (expansion tank) on my 03 MCS at 84Kmiles as well. I dont see anything on the driveway, but there are LOTS of white residues on the side of the tank, as well as on the heat shield under it. It seems to be leaking from the top (seam?).

Is this an easy DIY type job?

I am guessing I need to get #1 and #2 in this diagram, right?
http://www.realoem.com/bmw/showparts...36&hg=17&fg=05

Thanks!

 

Yes it is an easy DIY job. The new expansion tank comes with a cap from the dealer.

TOOLS -
10mm wrench or socket
pair of pliers to loosen hose clamps

*Loosen the clamp on the small hose. Remove the hose.
*Remove the two mounting nuts holding the tank to the firewall support.
*Carefully remove the plug on the back of the distributer module. This just makes it easier to remove the tank. The electrical connector has a push tab that releases the catch and you can slide the connector apart.
*Lift up the tankup. There are two mounting pins on the bottom of the tank that hold the bottom in place. Lift the tank up to clear the bracket.
*The cooling fluid will spill if any is in the tank. I just washed it off with fresh water to clean up the area. Just a side note - if you have pets don't lit them drink any of the fluid.
*Loosen the clamp on the larger hose on the bottom of the tank. Remove the hose and lift out the tank.
*Install is of course in reverse.
*Fill the tank with antifreeze mixture. (If you don't have the antifreeze it is only about a pint so just water would work.)

Like I said it is an easy job. Good Luck.

 

Thanks for the information and the short DIY instructions!

This morning, I checked the antifreeze/water level in the expansion tank, and the reservoir is almost full to the neck (the MAX line is halfway through the tank)! I dont know when it was filled that much, but it could be during one of the recent maintenance trips to the local shop. I guess they wanted to be nice but added a bit more than necessary.

So the question is... When I take out the extra water/antifreeze mix, would this stop the leak (i.e., less pressure, less liquid, etc)? Since it is leaking, does that indicate that the reservoir is toast and a new one is needed?

Thanks!