Yesterday I noticed my 2018 Cooper S Clubman's cabin air was no longer heating. (approx 70K miles). Checked to see in my Coolant reservoir no visible coolant. Filled it slightly above the "MAX" line and drove it again about 15 miles. After letting it cool down all of my coolant in the reservoir is gone again. Engine is not overheating and dash temperature gauge starts at COLD and never goes above the middle "OK" status.

I haven't removed the bottom engine cover to check for leaks, but I'm curious before I start digging if the likely culprit is the oil filter housing assembly vs. the water pump/thermostat. I saw a youtube video ( ) where the oil filter housing assembly allows the oil to be cooled and its just one big piece of plastic prone to leaks.

Does anyone have a service manual PDF or diagrams of where these components are located? Before I start digging and taking apart the car I'd like to at least have a map first. Any help would be appreciated.

 

Hello,

All the info is right here, get the metal version we have if you keep the MINI.

https://www.northamericanmotoring.co...s-done-it.html

 

Thank you! Turns out I don't think I have a leak.. The level just got so low that it disabled the heat and it took more than one filling of the resevoir to get it to burp and settle down. Heat is back on so I will keep an eye out for leaks.. But thank you for the info!

 

So where did it go? You're not in the clear yet.

 

Same place my coolant goes on my '17...wherever that is. I noticed my coolant 'disappearing' a couple of years ago when I had the same 'no heat' issue. My coolant was 60oz low at that time (~60K miles), so on average you could say 1oz/1000 miles. I was able to add coolant to my car and just let it naturally purge out the air over 2 weeks. There has never been any evidence of coolant in my oil (I do my own oil changes) nor anything under the engine/car (pull my underbody shield every oil change) nor in the combustion chambers (changed my spark plugs and they were not 'steam cleaned'). I am now just over 93K on the clock and still have a 'slow' coolant leak. Had to add 16oz at my last oil change and it is now back up in the 'normal' range along with good heat.

One theory out there is the coolant expansion tank cap venting coolant out. I haven't taken the time to get a new one, which apparently Mini has a later generation that may address the vapor escape over time. It has been pretty typical to add ~8oz of coolant every oil change since I originally found the low level, which is over 6000-7000 miles. That falls kind of closely with losing 60oz over 60K miles, strangely enough. The 16oz refill is likely due to the fact I didn't check/add any coolant at my previous oil change, so it doesn't appear to be accelerating in consumption as of yet.

The oil filter housing is certainly the most likely culprit if you start weeping coolant down the side of the block or end up with a milkshake in your oil pan. For those of us who don't have any typical signs of a coolant leak, best to keep a close eye on your reservoir and monitor, IMHO.

 

Well, my oil cooler finally gave out on me. Even though I have been very slowly losing coolant over the past few years, I could not find any evidence of an oil cooler leak on the underside of my engine or oil filter housing. I am guessing it was small enough to evaporate off the block before running down and making itself evident from below.

All that changed a couple weekends ago, where I lost all heat out of the vents over ~2 mile drive, so I turned the car around and headed back to my house. Glad I did, since that was the point the oil cooler ‘let loose’ and dumped most of my coolant along with a small amount of engine oil. I parked my car in my garage and ran my errands with my wife’s Wrangler. When I came back I was greeted with a nice puddle of coolant/oil mix on the garage floor along with a soaked belly pan.



So I got the car up on jack stands and pulled the belly pan to confirm the suspected failure. Yep, now I had plenty of evidence of an oil cooler housing failure, no doubt. Uugghh, now onto the interwebs to do some detail reading, ordering up some parts and reserving a rental car, since this is my daily driver.



I ended up ordering a Bremmen plastic housing unit and plastic BMW outlet connector, because both aluminum body versions were out of stock and I really don’t have the time to leave my daily driver up on the jack stands. Since the original units lasted 8+ years and 97K miles, I am not going to lose sleep with the new plastic parts. Only reason I replaced the coolant outlet connector is because I was in there and it was an easy item to replace. Thanx to ECS for the quick delivery time!

All in all it was not a difficult repair, IMHO, but having worked on my own cars for ~40 years may have something to do with it. It was easier than changing the timing belt/water pump on my former Subaru 2.5L. A couple of takeaways from the project: 1) You DO NOT have to pull apart/remove everything that the manuals describe, so long as you take your time removing/installing the fan assembly and oil cooler, 2) Removing the auxiliary water pump IS necessary and 3) You can pressure fill the coolant with a Mityvac MV8500 Silverline kit through the coolant pump air bleed line (see below).

I had only ever used my Mityvac kit for bleeding brakes, never to pressure fill something, but it worked great. Two engine air bleeding passes and my coolant has been steady for the past 4 days of driving.







I would also like to note another couple of interesting anomalies I ran into. Specifically with the tightening of the oil cooler housing to the block. First was one of the supplied screws in the Bremmen unit would not freely run down into any of the block threads, regardless of which position. It would bind up slightly a couple of turns in and be require a tool to run it down into the thread. I ended up reusing one of the OEM housing screws that would freely run down into the block by hand w/o a tool. Second was that the housing exhibited a significant ‘relaxing’ of the gasket, that I feel anyone installing a new oil cooler has to pay very particular attention to. I installed the cooler and torqued down the housing in the recommended torque sequence with a torque wrench to the specified 10 Nm. I decided to call it a night at that point and come back to finish putting everything together the next morning. When I returned, I decided to go back over the screws with the torque wrench just to check. Well, the #1 screw on the top-level position greeted me with ~1/2 turn before clicking at the 10 Nm setting!?! I followed the tightening sequence around the remaining (4) screws and did not get even 1/16th of movement from any of them…very interesting. I let it sit for ~2 hours and went back over all of the screws. This time I didn’t see any movement out of all (5) screws. That #1 screw is closest to where the housing fails and I am wondering if there is an unanticipated joint relaxation with the gasket on this housing design, which may contribute to said housing failure? Not sure just what kind of tightening strategy they use on the production line, but it may not be able to compensate for what I encountered. In any case, I strongly suggest letting the housing sit a good 4+ hours after tightening down the mounting screws and going back over all of them before putting everything back together.

I did go back and check the mounting screws on the coolant outlet fitting and they were rock solid at the original mounting torque, no relaxation going on there (whew!).

I ended up adding 1 gallon/128 oz/3.8L of 50:50 mix coolant to top things up. I also added 0.6L of oil to top the oil back up to ‘max’ on the gage. The shop manual states that you should add 0.4L of oil with the housing change and I guessed at the additional 0.2L based on what I saw sitting on my garage floor, which turned out to be about spot on.

If you have decent mechanical skills, this is a very doable job to tackle yourself. I could have done this repair in one full day, but took my time and completed it over a couple sessions over a weekend. Only tools I had to pick up were some external Torx sockets for the mounting screws on the coolant connector and oil cooler housing, otherwise everything else was in my tool box. YMMV.

 

Thanks for the update and glad we can help. Yep we sold out of the metal, very popular. We have the plastic as a back up and cost saver. The geomet coating on the screw can be built up or when you took the screw out their might have been slag on it. Also watch for gunk (from the area) to get in those holes. Thats my guess. Glad you got it fixed, we see when people have major leaks it soaks the fabric belly pan and it sags, thus new bremmen parts belly pan fabric is needed.

 

Well, the OEM part did last ~8 years and ~90K miles, so the Bremmen part should last well into the future. The fact that the Bremmen gasket/o-ring seal relaxes that amount is concerning in my mind for anyone else putting one it. If the housing isn't properly seated against the block and all sealing is relying on just the gasket/o-ring wall, I can see an early failure for these units.

I happen to work in Mfg and have dealt with fasteners/coatings for ~25 years. Short of bringing the screw to work and running a thread gage on it, it didn't show any excessive coating thickness, so I put it down to just a 'bad' fastener form. BTW, gaging of screw threads typically uses one tolerance range pre-coat and another post-coat depending on the coating. As for slag/dirt getting into that thread, it was one of the first things I looked at. There was some debris in that particular hole, which I cleaned out with some brake cleaner and a thread restorer tap. That did help the original screw hand thread into the hole, but that supplied screw on the Bremmen part wouldn't go into any hole w/o resistance, so it went into the recycling bin.

My belly pan did get soaked, but didn't suffer any 'softening' and sagging. I set it up vertical for a few days as I waited for my parts and it drip dried and dried out nicely. Luckily for me it went back up and is still as flat as it was originally, but I do know where to get a replacement if needed. Thanx.

My car did 'burb' a little more air when I checked the reservoir from 4 days of driving, just 2oz coolant brought it back up to the underside of the 'MAX' tab in the reservoir. Will check it on a weekly basis till my next oil change to see if any more air is hiding in there, but I can say my heat is nice and strong again!

 

Quick update ~2 months & 2,000 miles into the OFH replacement. No funny smells or evidence of any leaking anywhere I can see. My bleeding method of pumping it into the main water pump vent line, in conjunction with the factory coolant bleed cycle/method seems to have worked like a charm. Only 1 addition of 2oz of coolant in the first week and holding nice and steady since.

 

Thanks for the update.