Hello, have just joined today as I am after some help - I have pretty much had it with my R56 2007 Mini One.

Around a year ago it went into the garage after the car ran out of coolant whilst driving at speed, amber temperateure followed by red. The diagnosis was head gasket failure after the water pump failed, both were replaced.

Around a week after going into the garage we noticed the coolant level drop and the heater stopped working. Took it back to garage, bled and all OK.

Two months ago its started again, the symptoms are the amber temperature light comes on intermittently and we are losing coolant, so far I have (in order):

1. Replaced radiator - the old was leaking, didnt cure problem
2. Replaced thermostat housing - looked like it was leaking, research showed that was a common cause and seemed to have helped, still leaking
3. Replaced oil filter housing gasket - I noticed coolant was dripping from the Vclamp and directl under oil filter housing, it seemed to have helped but still leaking
4. Swapped fan relay and tested fan - have accessed the hidden menu to view temperature, the fan comes on as expected.
5. Checked for fault codes - purchased ODB2 reader and Torque and I have mapped temperature, it seems OK and no faults registered

As we stand today we are losing a small amount of coolant, I would say after a month the level will drop below the min line requiring top up. The coolant shows under the car, to the right of the vclamp at the bottom of the manifold - today I have discovered where it is coming from and I suspect its the head gasket. The engine does "feel" really hot when running and to me, it smells of burning when driving (but my wife and I are now overly paranoid!). Pictures to follow...

 

If I take the manifold off here is what I see, this is behind the manifold:



You can see why I would assume the leak is coming from the oil filter housing but its actually dropping onto the top of it and dripping down each side. I will post another picture where the leak is coming from.

 

The red line is where the leak is coming from, dripping down to the place showing in the first picture and then out onto the oil filter housing. Its definately not the thermostat gasket or housing, thats been replaced and is dry.

I can feel the head gasket and its wet with coolant - there is no coolant in the oil and the engine appears to be running fine, are there any tests I can do to check the gasket before I even consider changing it? Not sure if a compression test will show anything? I have put the car in and out of service mode three times now and I really dont want to have to do it again :(

Any advice?

 

Did they check the head when they replaced the head gasket? It may have wrapped, in which case it will never seal. If its not too bad, a machine shop can make it nice and flat again (deck it).

 

Thanks for the reply, I am sure they did check it and had it skimmed - but I can't be 100% certain.

It's one thing I will get done if it does turn out to be the head gasket, and it's something I can tackle at home (the decking part I will send the head off for )

Do you have any thoughts on diagnosing if it is a hg failure?

 

About the only way to know for sure is to do a blow down test. But if its not leaking into a cylinder, maybe you can pressurize the coolant system and see if it leaks around the head gasket.

 

Thanks, I'm going to have a propper look tomorrow. Can anyone confirm if it needs putting into service mode for the hg replacement? I hope not because I don't think I can face those plastic clips another time!

 

If you do pull the head off, also see if you can check the top of the block for straightness.

 

Hmmm, have done a pressure test on coolant system today and it's leaking from below the waterpump. I am in the UK and it's leaking under the left hand side, as you look at the car. The thing is its never leaked here before, only from the middle as picture shows above.

Could a leak from waterpump find its way to the middle only? Annoyingly, it was bone dry there today when I pressurised the system!

Nothing from the head gasket either. Really is starting to frustrate me and I don't want to waste any more money without concrete proof where the problem is.

:(

 

A pressure test uses more pressure than it would be during normal operation of the engine. I remember when I had a pressure test, it was 2-3 times more pressure than normal to force a leak to show itself. That's probably why it seemed to leak somewhere else do to the extra pressure, the leak will behave a little bit differently.

During my pressure test I found that the leak revealed itself when before during normal engine operation it did not, it was elusive. The cause of my water pump leak was do to Carmax (never take your car there!) using an absurd amount of gasket sealant in between the rubber gasket and the block, the seal was compromise.

 

Thanks, I just wasn't expecting it there. OK I'm certain I will be able to see the water pump if I take the wheel and liner off. Is there an easy way to get to the pipe that runs between the thermostat housing and pump?

When the HG was replaced by the garage previously the water pump was done also, so would be surprised if that's gone. Maybe it's the pipe that's split or cracked, but nod course I can't see that to confirm.

 

That pipe is a pain to replace, you must uninstall the thermostat housing and the water pump! There's a metal clip on the thermostat side that must be un-clipped to be able to remove the pipe from that end of the block, it wouldn't be the first time I have seen cracks and deterioration of the plastic at either end of the pipes connection.

 

Thanks, it was a pain to get the thermostat attached to the pipe when I replaced it (that clip!).

I am wondering if I have somehow dislodged the pipe from the waterpump side when I did thermostat. Looking on here it seems I can remove wheel, liner and I should get a good view of the pump from there. Hopefully weather will be good this weekend and after lots of head scratching I should come up with a plan of attack.

 

Well today I checked the pump, it only leaks at 30psi - I think that's twice "normal", anything less is fine. I found the leak though and it was the thermostat housing, even though it's brand new. Took lots of mirrors and lights to get a good view but as soon as I pressurised the system it leaked and dripped onto the head gasket, on from there.

That's now fixed, removed housing and used some gasket sealant as well as he original and it no longer leaks (nipped it a bit tighter as well than the 10nm I had done previously).

However...the engine is overheating. There's doesn't appear to be an air lock. Bleed screw doesn't produce air. After about 10 minutes the temperature jumped from 80deg celceus up to 120 and then back down to 80, all within a 50s period. The Amber light flicked on. That seems like a huge jump to me? The temp sensor is new and I've checked connections.

What would you do next now it's overheating? For me I feel like driving the car into a wall....

 

From personal experience using any gasket sealant is a big no no! The gasket needs a perfectly flat mating surface and gasket sealant messes that up because when it heats up, the gasket sealant expands pushing in-between the gasket grooves. I had CarMax install a new genuine Mini water pump and shortly after having it installed every time I turned off the car I heard this strange stretching noise! After a while my water pump started leaking slowly at the mating surface between the pump and block, the gasket sealant would expand and contract eventually pushing out far enough to leak. When you look at my picture you'll see that the gasket sealant doesn't really serve any purpose except to fill the gasket grooves which doesn't really do anything except to push on the gasket when the sealant gets hot.

My pump leaked at that gasket tab sticking partly out.

 

It also sounds like you still have an air pocket in the coolant system.

 

Well all is now fine, no more coolant leak and temperature is perfect. After I got back from first run out and calmed down, I realised there must have been an air lock. I am guessing because the thermostat wasn't open when I initially "bled" it in a rush, it wasn't yet up-to temperature.

I simply watched the temp and as soon as it got past 86 deg I bled the engine, plenty of air came out and it's been perfect ever since. Thanks for the help and advice everyone!

 

Found this thread, as it pertains to what i am experiencing, and judging from the location you pointed out, it may very well be the same for you...

https://www.northamericanmotoring.co...rom-block.html

 

If the do, make sure they are aware not the get into the stainless ball that plugs the oil port.

 

Getting the air out is a pain. I usually start it up and keep topping it off for 10 minutes. **** it of for about 5 min. Start it up again and repeat. Do that 2-3 times it's usually good. Glad to hear you got it. Couple posts ago you sounded frustrated. I've been there for sure. But hey, it gets easier. It's like they have zippers on them after awhile.

 

Well I am hoping this is the final post on this topic! After a long run out (the car is used mostly for short journeys) the gasket gave up on the thermostat housing and we lost nearly all the coolant. Luckily, no harm done.

Feeling frustrated I rang the local BMW garage and had a good chat, as the replacement housing I purchased wasn't a genuine BMW part they recommended replacing the gasket with the genuine part as a minimum. If that didn't solve it, then go with the housing as well.

£7 later I had a shiny new gasket and it was about 2mm thicker than the provided one and "looked" much better. I could visibly see 1mm of gasket ready to be "squished" before tightening against the block, now it's perfect. No leaks and it's been on lots of small and long runs, lots of heat cycles and dry as a bone.

My advice to anyone is if you buy a replacement thermostat housing and it's not a genuine part, make sure the gasket is up to the job and if your unsure get a genuine one.

Hope that helps someone one day