Coolant mystery...?
Discussion
2010 Mini R56 One (petrol).
About 1500 miles ago (car only does 500 a month) it started using coolant. No overheating or anything like that, just level dropping in the expansion tank then one day noticed it was nearly empty. Past momth has needed topping up a couple of times so time to investigate.
Did the normally looking and prodding, ran the car for an hour on the drive with no effect. No drips or anything on the cardboard underneath.
Bought a pressure tester (had to fiddle a lid to get it to not leak) but that didnt prove anything either.
Now added 30ml of UV dye, dropped a Jnr to work to get it circulating and then hunted with a UV torch... nothing.
Now pressurised again to 15psi (still at 15psi after 10 minutes). No visible leaks or sign of glowing under the bonnet or on the floor.
The oil filler cap is perfectly clean (has been for 3-4 months since oil change) and no flourescing inside or out.
It must be going somewhere. No gunk in oil, no whisps of smoke or anything from the exhaust. No visible leaks (so far).
The normal weak point of the thermostat housing was replaced 12 months ago and I've looked at that as carefully as I can.
Any other suggestions?
About 1500 miles ago (car only does 500 a month) it started using coolant. No overheating or anything like that, just level dropping in the expansion tank then one day noticed it was nearly empty. Past momth has needed topping up a couple of times so time to investigate.
Did the normally looking and prodding, ran the car for an hour on the drive with no effect. No drips or anything on the cardboard underneath.
Bought a pressure tester (had to fiddle a lid to get it to not leak) but that didnt prove anything either.
Now added 30ml of UV dye, dropped a Jnr to work to get it circulating and then hunted with a UV torch... nothing.
Now pressurised again to 15psi (still at 15psi after 10 minutes). No visible leaks or sign of glowing under the bonnet or on the floor.
The oil filler cap is perfectly clean (has been for 3-4 months since oil change) and no flourescing inside or out.
It must be going somewhere. No gunk in oil, no whisps of smoke or anything from the exhaust. No visible leaks (so far).
The normal weak point of the thermostat housing was replaced 12 months ago and I've looked at that as carefully as I can.
Any other suggestions?
LordLoveLength said:
Heater matrix leaking inside the car?
Have you taken a sample of coolant to test the UV dye? You may still have a slight leak and not enough dye to show it.
Does the car have a slight misfire from cold? A leak into a cylinder usually causes misfire on cold start.
Starts and runs as always, no codes and smooth as silk (new chain, vanos etc etc) will check the dye ratio though and the heater matrix (did check this for other reasons a while back but will do again).Have you taken a sample of coolant to test the UV dye? You may still have a slight leak and not enough dye to show it.
Does the car have a slight misfire from cold? A leak into a cylinder usually causes misfire on cold start.
Just refilled the coolant, ran on ramps for 20 mins and still cant see anything
If the head gasket test doesn't highlight a problem so the coolant isn't going out through the exhaust, try changing the coolant expansion tank cap if not already done. They're cheap and prone to fail with age and only show a problem when the car is up to temperature as steam leaks out.
If the level is only dropping slightly and slowly it may be a tiny leak you need to leave the dye to taint more wherever it's escaping. Check you can see the UV dye by dipping the coolant tank with something so you know the concentration is sufficient to see.
If the level is only dropping slightly and slowly it may be a tiny leak you need to leave the dye to taint more wherever it's escaping. Check you can see the UV dye by dipping the coolant tank with something so you know the concentration is sufficient to see.
Virtual PAH said:
If the head gasket test doesn't highlight a problem so the coolant isn't going out through the exhaust, try changing the coolant expansion tank cap if not already done. They're cheap and prone to fail with age and only show a problem when the car is up to temperature as steam leaks out.
If the level is only dropping slightly and slowly it may be a tiny leak you need to leave the dye to taint more wherever it's escaping. Check you can see the UV dye by dipping the coolant tank with something so you know the concentration is sufficient to see.
Yeah, I think this one could take longer than a few hours to solve.If the level is only dropping slightly and slowly it may be a tiny leak you need to leave the dye to taint more wherever it's escaping. Check you can see the UV dye by dipping the coolant tank with something so you know the concentration is sufficient to see.
Waiting on the HG tester kit so will be doing that this evening and will look for evidence of a leak again at the end of the week.
Failing that, new cap/tank although that it popping as the caps open when warm.
Keep eliminating things. Hope its not HGF or thats something that will have to be done, the joys of sheds.
Okay, so after 10 minutes of bubbling the blue fluid is as blue as when it started.
Also, (in the dark with the car on ramps) I checked everywhere for a trace of UV dye. Nothing.
However... I am now told that the fan has been cutting in as much as it used to.
I think I may have been on a bit of a wild goose chase on this one.
Next thing it to check the fan (which works when the thermostat is unplugged) and the thermostat itself.
I have a feeling coolant is only lost when it gets hot.
Also, (in the dark with the car on ramps) I checked everywhere for a trace of UV dye. Nothing.
However... I am now told that the fan has been cutting in as much as it used to.
I think I may have been on a bit of a wild goose chase on this one.
Next thing it to check the fan (which works when the thermostat is unplugged) and the thermostat itself.
I have a feeling coolant is only lost when it gets hot.
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