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Discussion Starter · #1 ·
I have a Mini One First 2010 1.4 N12 engine. A few weeks back I found I was losing coolant so left to the garage and they changed the thermostat housing as it was leaking and thermostat was stuck open. I'm not sure if it matters for this engine but the new housing has a green connector where I've seen @mike1967 recommend an updated one for 1.6 engines that has a brown connector.
All was good for a few weeks but then I started losing coolant again. Only a small amount at first but then it dropped almost to the min and has turned a browish colour. Back to the garage with it and they now think it might be oil in the coolant and that it could be a problem with the head. Car is running great, idles steady, no constant smoke out he back that I've noticed yet. Uses a good bit of oil bit I've learned to live with that. Garage say they can't find any leaks, oil or coolant. I was hoping someone might have some other ideas as to what to check.
 

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genuine housing are brown temp sensor, green ones tend to be cheap copy's and not that good,
as for water and oil mix could be the oil filter housing the rubber seals to the block has cracked and leaking across , or more likely and head gasket or cracked head at worst. could do a sniff test as below link
more professional one below
BT-500 Universal Petrol and Diesel Block Tester / Head Gasket Test Kit. T374100 | eBay
 

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Discussion Starter · #3 ·
Thanks @mike1967

I'll get that tester ordered and see what it shows. I had read about the oil filter housing seal and was going to get that replaced. Would it be worth replacing that before doing the sniff test?

Had the car out for a good drive this morning and its driving great. I let it idle when I got back and monitored the coolant temp using the secret menu. It got to 112C and the big fan kicked in. Seems high from what I've read before, 108C is correct. I assume his is due to the green temp sensor?

Exhaust is clean when idling. If I rev it hard I get a little bit of white smoke and then it's clear again.
 

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Discussion Starter · #4 · (Edited)
So I got the test kit today and ran the test. All good. The fluid never changed colour. It was the cheaper kit from ebay - not the one you linked to @mike1967 but same idea


That one was more local to me.

I ran it for over 10 mins. Holding revs at 1500-2000. Test solution bubble a good bit so whatever gas was coming out was not affecting it. Maybe trapped air in the system and that's why coolant was dropping? I let it run until the coolant started to come up into the test tube. I hope that means all the air is out now.

** edit to remove videos as I had deleted them **

So now the question is how reliable is that test? :)
 

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its reliable its chemical reaction to the solution no different than hot tub water testing strip are if that makes sense, only other thing is do a pressure test loan a water coolant pressure tester kit like below link.
with plugs out and engine hot pressurise the system and go find the leaks , if head gasket only leaking one direction you will get water build up in a cylinder if pressurise the system for a hour or so . can use small camera cable down plug holes .
 

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Discussion Starter · #6 ·
Thanks again @mike1967

I'm learning as I go here.

So if I understand correctly the sniff test tells us the head is not leaking in relation to the combustion chamber?
The pressure test will tell us if it leaking internally to the cylinders?
If nothing shows in plug holes then is head okay?
Of course leak still has to be found but at least it should be easier with system under pressure,
 

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Discussion Starter · #7 ·
Just to add I can't get any kind of a sweet smell from the exhaust either. I've seen that mentioned as a potential way to tell if the head gasket is faulty
 

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Discussion Starter · #8 ·
@mike1967 thanks for all the advice so far. I think the car needs valve stem seals doing. It's burning oil and failed NCT (MOT) on emissions. As the head has to come off for this anyway I think worrying about coolant leak and head gasket is pointless :)

I've seen your post about rebuilding here mini one 1.4 rebuild 2008 & 2009 cooper s jcw which is very good.

Besides the timing chain and water pump are there other parts that you would always change? For example I see some timing belt kits online with VVT hubs included. They're quite a bit more expensive than the standard kit and I was wondering if these would normally be needed. I don't want to replace parts unecessarily.
My mechanic will be doing this and we've agreed to replace anything that is suspect but of course that potentially opens a big can of worms. A list of always replace parts would be great and also a maybe replace depending on condition.
I've searched around and found some good info but not sure if everthing is covered.

I'm trying to cost everything up at the moment and decide if it's worth it.
 

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would only fit genuine vanos hubs,, vvt is something different ie high lift valve on inlet, if pulling head would also pull sump pull pistons and fit single piece oil control rings a must do job on them as per my link
 

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Discussion Starter · #11 ·
Thanks @mike1967. I'm in Ireland so I'll have to get a local guy to do it :) The price I've been quoted is not far off that.

The car has done 196000K and I've no real service history for it. I've had it for a year and have some receipts from work done in the previous 3 yrs.

I'll be shopping around but this is the full timing kit I was looking at. Is this bigger kit a better option?


I'm building a checklist and parts list based on your posts so I might post that later and if you have time maybe you can check it for me.
 
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