Coolant disappear then reappear!

Coolant disappear then reappear!

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Discussion

Ian187

Original Poster:

407 posts

252 months

Thursday 4th June 2015
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I've been losing a bit of coolant regularly on my Mini Cooper and just been topping up here and there! Took it to a garage that suggested they need to replace all the gaskets (head etc) so I took it to another garage and they said nah it's just a leaky radiator (which made more sense) and I was waiting for them to have time to change the rad! However the last couple of days it hasn't lost any coolant and in fact yesterday the coolant reservoir started filling up!!! Today in hot weather I drove it and the engine temp started going up so I stopped and the coolant reservoir is now overflowing! This doesn't sound like a leaky rad now!! The rad fans cut in and I let the car cool down before dring home! Any ideas what this could be?

mike9009

7,477 posts

249 months

Thursday 4th June 2015
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Hi

Could the Rad be furring up? So now it is blocked? When the car was loosing coolant what were you refilling with? The blockage ( or lack of flow) could also cause it to leak and potentially back fill the overflow (just guessing at that but sounds plausible) ..... I will wait for someone with more knowledge.....

What age is your car?

My 2007 Cooper S recently was loosing coolant (at an alarming rate!). It was the thermostat housing

Ian187

Original Poster:

407 posts

252 months

Thursday 4th June 2015
quotequote all
Thanks Mike, it's a 2004 Mini Cooper.
I was refilling with just boiled water from the kettle, funny thing is the coolant reservoir was just taking this fresh water and the coolant was just clear / water coloured. Now it's suddenly refilled and overflowing it's bright pink which is what the previous antifreeze was! Seems like maybe a massive air lock or something, but seemed funny I was regularly topping up and now it's suddenly overflowing! Like you say maybe the leak fixed itself / furred up! .???

MrTickle

1,825 posts

245 months

Friday 5th June 2015
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I suspect that the topping up has caused an airlock in the system, which upon getting hot has created back pressure.

I had the same occur to me a few years ago on a another car. A replacement radiator will involve a system drain and refill obviously so that will also clear any air.

Ian187

Original Poster:

407 posts

252 months

Friday 5th June 2015
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Cool, is there any easy way to get the airlock out without draining the system?
The car overheated yesterday so just thinking maybe that block of air is stopping the coolant flowing round, would be good to clear it even if just to drive to the garage safely!

Ian187

Original Poster:

407 posts

252 months

Friday 5th June 2015
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Or do you think it's safe enough to drive as long as I keep an eye on the temp and stop if it goes high!

t400ble

1,804 posts

127 months

Friday 5th June 2015
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Dont keep driving the car

You have an airlock. The system isn't working correctly, get a new rad ASAP if that is the cause of the leak

Ian187

Original Poster:

407 posts

252 months

Friday 5th June 2015
quotequote all
Yeah, but do you think it's OK to drive to the garage, is what I'm thinking! 10 miles! Would be a massive pain to have to get a tow truck just for that!

Ian187

Original Poster:

407 posts

252 months

Friday 5th June 2015
quotequote all
Spoke to a mechanic who advised me to "burp" the system! Take rad cap off and run the car! When car comes up to temp all the air will prob suddenly come out and you need to keep a big bottle of water to top up as the air comes out! I did this and pretty much exactly that happened! Ended up chucking over a litre of water back in, seems OK now, I'm sure I'll prob have the small leak still, but feel happier about driving it to the garage at least now.

keirangrogan

486 posts

270 months

Monday 15th June 2015
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Ian187 said:
Spoke to a mechanic who advised me to "burp" the system! Take rad cap off and run the car! When car comes up to temp all the air will prob suddenly come out and you need to keep a big bottle of water to top up as the air comes out! I did this and pretty much exactly that happened! Ended up chucking over a litre of water back in, seems OK now, I'm sure I'll prob have the small leak still, but feel happier about driving it to the garage at least now.
Having similar problems with my wifes car which is now visibly dripping onto the floor. The car, not my wife, those days are long gone!!

However, if you want to bleed the system properly, there is a bleed screw just in front of the intercooler, looks like two pieces of the pipe have been joined together and there is round plastic disc about the size of 10p with a cross on it. undo a few turns or even take it out as long as you don't lose it. Once engine gets to temp, the air will escape from there. when water starts to come out tighten it back up.

Oh, and if you use non water coolant such as "Prestone" available at Tesco £6 a litre, it doesn't boil until 123 degrees, 23% higher than water.