2011 Mini Cooper S, 67,000 miles. R56, N18

So I am driving my car today (about 30mins) and after I stop and come off the highway to the light I see light smoke coming off the hood. I immediately stop my vehicle. Restart it after the light and drive it to the next gas station. I pull it over and:

• The coolant reservoir is empty.
• There is coolant sprayed in the engine bay on the right hand side.
• I get some water fill the cooling reservoir and it seems to mostly pour out of the first hose near the oil filter but in general I can't tell where it is coming out from?
• Car starts and runs fine.
• Towed the car home and when I got home I see a little bit of coolant on the floor of my garage (about 1/8 of a cup or less) so it apparently was leaking when I started the car up and drove it to work this morning. It is aggravating that this stupid car can't sense and warn there is no water pressure with the car at temperature. If the car was smoking, it had to be overheating at least a little bit. I love the car but it is like a moron designed most of it. lol
• I never got a dash light.
• I never got an overheat light.
• I ran a computer check and I don't even see any codes thrown.

Any idea of a good way to troubleshoot this? My first guess is the thermostat and housing as I know that is a common failure point of the car but I don't even know where that is. It sure isn't obvious. I guess it could also be the water pump probably? I would think the car would make more noise if that was it. I did notice a few days ago when starting it cold more noise than normal and it almost sounded like the death rattle but figured I was just being paranoid.

 

Thermostat. Or crossover tube. You’ll be replacing them as a pair anyway. On a related note might want to do the pump too since it too is a lot of plastic. Other item near oil housing is the temp sensor. Might have sprung a leak. Last item would be the oil filter housing thing. Check to make sure that seal isn’t bad and coolant is getting in oil.

the thermostats go differently. Ours just started leaking more and more one month.
could have been seeping a while as the trans catches a LOT and can burn off most.

the stat is under the fresh air intake tube above trans. It looks like a heart with like 7 tubes clamped to it. Royal PITA.

 

Yeah it looks like a Royal PITA. $100 and at least 4-6 hours for me or someone who has never done it before including coolant. Pretty much every other car, it is a $20, 15 mins job. I believe most of the coolant spilled is above the Transmission and that is the first place I noticed the smoke as well. My understanding is 65K is normal time on this car for Thermostat and housing.

Is the cross-over tube the thing that requires removing the intake manifold to get to ? I'm not sure I want to really replace that do I?

 

Most likely the temp sensor in the radiator hose controlling the thermostat (is on the right side near the oil filter). My 2012 is leaking there. The bummer is MINI no longer makes/sells that sensor. You have to replace the thermostat housing (which now contains the temp sensor) and the radiator hose.

 

This is not quite correct:

Initially, cars were fitted with a thermostat housing that had no seperate access to the (integrated) temperature sensor. At some point they switched over to housings allowing separate access to the temperature sensor and used the new variant also when the original thermostat housings had to be replaced for any reason (thermostat malfunction, temp sensor malfunction, leakage). A wire adapter is required in such a case to accomodate the different wire connections of the two variants.

My non-S R 56 LCI manufactured in November 2010 had the original housing from factory. When the temp sensor failed in 2017, BMW Germany replaced it with the new variant with individually replaceable temp sensor.

Aftermarket housings may be of either of the two variants, buyers should (imho) insist on getting the new one along with the wire adapter.

 

Confusing. How do you know which one you are getting? Is there a part # difference.
For example, is this the new one or the old one. IT looks like the sensor comes off so I presume this is the new one?
https://www.ebay.com/itm/NEW-THERMOSTAT-HOUSING-AND-GASKET-FOR-07-13-MINI-COOPER-R55-R56-R57-11537534521/302036990695?fits=Year%3A2011%7CModel%3ACooper%7CM ake%3AMini&hash=item4652cebae7:gPQAAOSwFpVcbRUT
I'm guessing this is a picture of the temp sensor.

 

How can a temperature sensor cause a "leak"? It is an electrical connection.

 

Of course there is:
https://www.realoem.com/bmw/enUS/par...&q=11538699290

For more detail, including the part number of the required adapter:
https://www.realoem.com/bmw/enUS/sho...diagId=11_4551

Correct, though the part number shown is of the original, superseded version. Buy the seller!

 

AZdsrt probably meant that the temp sensor failed, allowing the closed coolant system to reach higher than specified temperatures/pressures and eventually rupturing at the weakest points. Whether or not that is probable I don't know, the thermostat may well be designed to open at a certain temperature/pressure by itself and independently of any command by the ECU.

 

had something similar of '15 R59 recently. Saw some coolant on the garage floor and found resiv' down so topped it up and made appointment with dealer (warranty) assuming it was thermostat.

TURNED OUT TO BE "full flow oil filter housing gaskets leaking (coolant side)"

not an easy one either ....

so b4 you start ordering parts . . .

#############################
p.s. if you are not original owner note there is a 'limited warranty extension' for the thermostat housing with thermostat .... extension is 10 years / 120,000 miles. Applies to SOME VIN .. not all. 800-831-1117 reference M-ELWR 2018. I got my letter April 2018

 

How can a leak in a oil filter housing cause all the coolant in the system to spray out into the engine bay and when whatever coolant you put into the reservoir will end up on the ground? Coolant and oil never mix in the system?

I had contacted Mini before to find out what was extended and this is what they told me.

 

I don't think this is my car. I have a Mini Cooper S. This is my car here-->
https://www.realoem.com/bmw/enUS/sho...diagId=11_4551

However, this is beyond confusing since you are right it lists 4 part #s, 2 that have ended. I don't see where you can just get the thermostat though. Part# looks to now be:

11538674895

https://www.ecstuning.com/b-genuine-...t/11538674895/
And I would need this thermostat adapter?
https://www.ecstuning.com/b-genuine-...r/12518611289/

Ebay version: https://www.ebay.com/itm/Thermostat-...sAAOSwcs1b6nMF

 

why does coolant route thru the oil filter mount? NO IDEA ... but it does! That's what they replaced and my leak is gone ... and they were not in the LEAST bit surprised ... it is a common issue. If you have coolant ... it is under pressure when the engine is hot .... that's just how things work.

 

Ok, my engine won't hold coolant at all. So it has to be some kind of gigantic failure. This does look like a massive job all around. Is there anyway to tell when the coolant is coming out or to isolate these two issues?

 

Is there anyway to tell when the coolant is coming out

re group and come back tomorrow . .

 

Nope. The pic isn't great, but the sensor is dead center in the pic. The seepage is highlighted. I had it into a Mini dealer a couple of weeks ago for service. The tech pointed it out to me, said it's a common problem. The repair was to replace the radiator hose containing the sensor and the thermostat housing.

 

Hope this helps.

 

I can see the coolant is all leaking over the transmission and is coming out roughly in the middle left (driver) side of bottom. I don't see any coolant coming out of the passenger side of engine.
It is an absolute mess of pipes, wires and hoses down there so I really can't see much of anything even after removing stuff.
I don't even see the bleed screw that is supposed to be above the thermostat housing to try and orient myself.

 

The water pump is on the other side of the engine from where the leak is occurring. Why would you suspect the water pump when all the coolant coming out appears to be roughly middle driver side?

 

The only reason I mentioned the water pump is you said the leak was evident on the right side of the engine, by which I thought you meant the passenger side. If your leak is in the drivers side, it could be your thermostat, or your oil filter housing gasket ( possible culprits).

Also, I’m making a very American assumption that your car is left-hand drive. Sorry if that’s not the case.

I had a hard time finding the bleed screw the first time also. It’s just black plastic like the rest of the thermostat. But it’s right on top and you can reach it with a long screwdriver without moving anything. Use a really bright light and you’ll probably find it. Once you find it, it’s hard to forget where it is.

You might try looking at a picture of the thermostat at Realoem.com. I think it might indicate where the bleed screw is.

Message me if I can help you troubleshoot some more.

 

Yeah, I hate that right side/left side stuff. Right side when looking at. Actually more center than even drivers side of engine. I now have a wand light. I really can't find a leak yet. I'm almost thinking it is a hose. The bleed screw is next to the thermostat. I have a single thermostat connector at the top it looks like. I don't still don't see a bleed screw next to it. I have to find it because if this is just a hose and this point I'm going to need to drain and refill the radiator. At the service station, the only thing I could buy was spring water to try and refill it to try and find the leak. The coolant system is contaminated at this point and will need to be drained and refilled.

The hose at the bottom of the expansion tank certainly doesn't look right and I now there was a small amount of coolant leaking there the last time I changed the oil. Has anyone found a way to fix that yet with a quick-disconnect or something?

 

The hose at the bottom get alot of use. We found this short piece can be swapped out so you dont have to get the whole hose set. Just replace it. From oil changes all the time they get stressed.

https://www.northamericanmotoring.co...onnection.html

 

It is possible that is all it is. I ordered the brake bleeder system and once I get that in. I'll try and locate the leak. Do you have the ECS part#?

 

Its linked, but here also

https://www.ecstuning.com/Search/Sit...h/11537600674/

 

Thanks.
I am 100% sure this was leaking a tiny bit off coolant the last time I changed the oil but it stopped. I wonder if the coolant got below this point and every time it heated back up and expanded it came out of the hose there?

It could be heat sensitive. Rubber expands and gets more pliable and leak prone when it gets hot...that is the problem.