Air lock? possible leak?

[harvey94]

Hi,

I am trying to help out my friend find out what is wrong with his mini one 2002
Basically he had the coolant flushed out and a new thermostat changed as this was staying open and causing issues with heating, everything is fine now with temp gauge and heating, however, the coolant level on the expansion bottle seems to be dropping, the strange thing is it had risen a few weeks back from 3/4 to max level, now after a few weeks the level on the expansion bottle is at half way between max and min, when you open the filler cap with yellow warning label it always seems full and that you couldn't add anymore fluid here, it just seems to be at the expansion bottle, the lid seems to seal fine and we can't see any cracks, could this just be a case of an air lock or could anyone suggest what else it could be and also is there any reason to be concerned and get it straight to a garage? Car runs absolutely fine, no over heating.

Thanks!

[marque]

Hi

The expansion tanks do leak and can be a pain to detect, you could try removing it blank the holes off and fill it with hot water out the kettle. If there is a crack it will open up.
The other idea is may be the rad cap is on its way out and might need to be changed.
Also you say the thermoset has been changed have a good look around it see if there is any water marks or water sitting just below it The housings are know problem erea

[harvey94]

Hi,

Many thanks, great help, will check all you have advised and see how that goes!

[harvey94]

Hey,

Ok so i had a quick look tonight but it bloody freezing! , i can't see any water laying anywhere but what did happen was when i opened up the radiator cap the expansion bottle rose straight away! would this indicate an air lock? i had a look for the bleed screws but could only locate 2 , one on the hose beside the rad to the left and the other just below the battery compartment, can this cause any problems if the air lock remains? or will it just sort itself?


Can i please just ask another quick question , my friend filled his tank to full so which should be 50L , he had done 196 miles at half a tank but for some reason the car is now at 1/4 tank and shows 236 miles, has anyone heard of this before? Could it be linked to the coolant at all? would this affect MPG?

Thanks!

[marque]

Hi ya

Have a look at his link may help you with the bleed point also remember to put you heater to hot and max on the blower this opens he valve and makes shore water is passed though heater in the car may ave a little air in there.

http://www.mini2.com/forum/maintenan...screw-plz.html


The mileage I think is calculated from remaining fuel and average mpg so it can vary up or down quite a lot. Remember in the cold weather the car will use more fuel because it takes longer to warm up. All you need is a sensor to be on a limit and that does not help there built to a tolerance so not much you can do.
Just as a heads up
If the car does drink fuel and you mpg drops a lot and the car runs rough and starts to lose power it my be a sign of you pre cat O2 sensor failing this sensor does not bring on your EML light
Work out your mpg per tank full don't trust the inboard computer

[harvey94]

Hi,

I must thank you as you have been a big help! I will follow the instructions from the link and make sure it's bled ok then keep an eye on it.

With regards to the MPG I can only go with what the gauge reads and I do realise these can go faulty and not be 100% but the last time he complained I asked him to run it and keep an eye on it so when the gauge got under a quarter I took it to petrol station and managed to put 43L in which went the gauge was working as it should and reading ok, if I am working it out correct then he would be getting about 26 MPH which for a mini one 1.6 I thought was not great! The car 100% does not get driven hard and never goes above 65 on the motorway, no lose of power at all and no sign of running rough , what I can't understand is for the half a tank it seemed fine then the last half just dropped so fast! He has had problems with MPG but it was put down to thermostat faulty and also had a full service including spark plugs, thought it was fine as of the first half of the tank but now seems to be burning more again!

[marque]

Hi ya

No problems also a thing to consider is the DME (cars brain) is self adapting so it may take a little while to sort its self out.
If you have not had the battery disconnected during the work you my find resetting the DME might be worth a try
if you have not done it you can reset the DME by disconnecting the battery and holding the pos and neg together or 10 seconds or just leave it disconnected for a while 30 min or so should do it
Fuel consumption will vary on the weather anyway keep us upto date good luck

[RachCooperS]

I'm having coolant issues at the min with my R53 Cooper S. The coolant level seemed to be going down each time I drove the car there was also that watery sloshy noise coming from the passenger footwell. The OH is a mechanic and said the thermostat housing was leaking. Spent £100 on a new part. Now the system can pressurise properly other leaks have sprung up and I'm losing coolant again. Waiting on a piece of piping which is on back order, meaning the Mini is off the road for at least a week. Hope this new part solves it or I'm faced with using the OH's crappy burgundy Volvo estate. :-(

[harvey94]

Hey,

Just a quick question, would it be safe to assume that if i had a leak in the system i would be able to open the rad fill cap and top it up? what i mean is is that anytime i open up the rad fill cap its full, i am only going by the expansion bottle level that is dropping but can also rise! today i checked the level before attempting to bleed, it was just above min, so i started engine and turned up heat, opened the rad fill cap and opened the first bleed screw, no air , just coolant, the second one that lies below the the expansion tank has been all threaded!! would need to get a small pair of grips and someones small hand! , i gave the big hose a good few squeezes and the level on the expansion tank rose. It was just to rule out a leak, if i never can fill from the rad cap would this indicate the system is holding fluid?

Thanks!

[mab01uk]

The expansion bottle level is supposed to rise and fall depending on temperature of engine and coolant but should remain between max and min levels without frequent topping up. The pressure cap if working correctly pressurizes the system to raise coolant boiling point and allows the coolant to pass back and forth from the expansion bottle as required with expansion, etc.

On Mk1/R50 Mini One/Cooper the pressure cap is on the engine near the thermostat housing and should be checked or replaced if it is not sealing or pressurizing the system correctly which can cause overheating and loss of coolant. The expansion bottle has a plain flip-off filler cap.

(The Mk1/R53 Mini Cooper S with supercharger however has the pressure cap fitted to a larger plastic expansion tank).

[harvey94]

Thanks mab01uk , thats great to know! it was going below the min level often but then the system was bled and thermostat changed, now it has never gone below the min level but does rise and fall, as you say this is normal so thats great!


Now just need to figure out the MPG! it could well be as its an older engine you can't expect the best but it was just really strange that for the first half a tank it read just under 200 miles on the clock as it was set to zero when filled the tank, then on the other half a tank it is now at 1/4 and reads about 236! if i work it out correct that would be getting about 24-26mpg on a 50 litre tank, no hard driving at all, little city driving but some cold runs.