Mysterious loss of coolant.

[Hotfuz]

Over a week ago I had my air con serviced and naturally the engine was left to idle on a warm day on the drive.

The air con works perfectly and so I parked the car (1.7) back into the garage and left it for a good few days. There was no wet patch or obvious loss of water on the drive however when opening the garage door there was an obvious large patch of coolant under the car which had soaked into the garage carpet.

Under the bonnet was nothing obvious, the expansion tank was empty and the only tell tale sign of a water leak was the residual drips around the sump of the engine and nothing obvious from any coolant pipes. Again only small amounts of pooling around the gearbox fins.

I refilled the expansion tank and tried to copy the scenario and left it run for some time however sadly there is literally no signs of a leak!!

The only theory I have is that when having the air con serviced, this was the 1st time the car has run since November which is when I had the cambelt done & remember I had a nightmare trying to bleed the system.

Is it plausible that there was still air in the system and due to the weather being warm and more strain on the engine with the air con running that this made the expansion tank cap release enough coolant after I parked up not realising there was an issue?

Any thoughts would be appreciated, I am led to believe the Puma & Fiestas of that era are prone to air locks?

I have ordered some new coolant pipes & a new expansion tank anyway just in case.

 

[Edge]

Hi. It is possible the liquid under the car was condensation dripping from the air con pipework. I sometimes get this on mine. Otherwise for me the only coolant leak I have had is from the thermostat housing.

 

[Hotfuz]

Hi. It is possible the liquid under the car was condensation dripping from the air con pipework. I sometimes get this on mine. Otherwise for me the only coolant leak I have had is from the thermostat housing.

No definitely coolant as the expansion bottle was empty and the fluid on the carpet was quite a lot and 100% coolant.

The pipe that condenses water from the ac is further back towards the exhaust

 

[Mukamika]

I think it`s most likely coincidental that you are connecting it with the air con. I guarantee you have a coolant leak, you`ve just got to track it down, if you`re using the ford stuff it`s red and usually leaves a pink stain, check all pipe and hose connections, heater valves have been known to leak as well as the thermostat housing. You could remove the expansion tank and test that seperately rather than spending out on a new one.

 

[Hotfuz]

I think it`s most likely coincidental that you are connecting it with the air con. I guarantee you have a coolant leak, you`ve just got to track it down, if you`re using the ford stuff it`s red and usually leaves a pink stain, check all pipe and hose connections, heater valves have been known to leak as well as the thermostat housing. You could remove the expansion tank and test that seperately rather than spending out on a new one.

I draw reference to the air con not suggesting it is the ac but simply the fact I have only used the car twice in 6 months, when I had the cambelt changed and having the ac serviced a couple weeks ago with the car parked up running for a while putting more load on the cooling system so perhaps a coincidence but nonetheless connected

 

[Sjoerd]

If you want to be sure you'll have to have it leak tested. Basically put slight overpressure on the system and see if it remains stable or starts leaking somewhere.

 

[Mukamika]

I understand your thinking but one way or another you have a coolant leak, as you didn`t use the car much over the two months it could be small or big but there will be a sign if you look carefully. People often go to a garage, get the car back, find something wrong and conclude the garage did something, but in this case the ac system is totally separate, water pump is located under cambelt, it is possible of course if the garage didn`t check the level once finishing the cambelt and topping it up after bleeding, hunt for a stain and you will find it. Hopefully you had a new water pump when the cambelt was done as it`s very difficult on it`s own, always a good idea when the cambelt is changed, hopefully this helps. If not top up the expansion tank, run the engine and let the cooling fan cycle and lie a large piece of white paper or cloth under the engine and wait for drips.

 

[Hotfuz]

Used the car yesterday on a long run, no leak!

The question I initially asked was has others had issues with air locks which would cause extra pressure in the cooling system which in turn forces the cap of the expansion tank to release the over pressure.

Water pump was replaced and as mentioned I had issues at the time of the cambelt change of getting the air out of the cooling system which was down to air in the system.