VW coolant Sucked up
Discussion
My Wife's 2012 Tiguan with the 2.0TSI engine threw up a coolant red flashing light this morning. We pulled over immediately and turned off the engine. The car was not running hot so I do not think there is any concern about damage. I checked the coolant level and it was all gone. I released the pressure slowly to see if it would come back and got nothing. I assumed I had a leak but there was no evidence. As the car was not running hot I drove it to the nearest garage and bought more coolant. When I checked, the level was back to where it should have been.
Why would my coolant system behave in the manner?
Why would my coolant system behave in the manner?
donkmeister said:
Have you checked the oil for mayo?
It's going somewhere, whether it's leaking out onto the road, or getting into the oil, or getting into the cylinders and leaving via the exhaust.
I'm pretty certain it'll be the water pump OP. Have a google, seems to be a known fault. It's going somewhere, whether it's leaking out onto the road, or getting into the oil, or getting into the cylinders and leaving via the exhaust.
It's normal for the coolant to run back into the reservoir when you remove the cap just after it has been switched off.
Check the coolant level when the car is stone cold first thing in the morning and if low top up with the correct mix of G13 and water and then monitor the level to see if it drops. If it does, have the system pressure tested to identify if thete is a leak.
Check the coolant level when the car is stone cold first thing in the morning and if low top up with the correct mix of G13 and water and then monitor the level to see if it drops. If it does, have the system pressure tested to identify if thete is a leak.
h0b0 said:
The car was not running hot
If you're relying on the gauge to tell you that, you could be fooling yourself. The gauge will only show you the temperature of its surroundings. In a normal healthy engine with coolant circulating everywhere, this will be the coolant temperature and the sensor would typically be positioned to be at / near the hottest point in the circuit. But if you don't have coolant circulating past the sensor, that no longer tells you anything about the temperatures elsewhere. You could easily have coolant boiling out of the heads while the sensor shows a normal engine temperature.I dropped the car off at the dealer yesterday. They were confused as to why I didn’t just top up the coolant. I told them it will randomly be at the correct level independent of temperature.
I looked at changing the water pump myself but it seemed too involved for me right now having moved and changed jobs in the last 2 weeks. Also, here in the US manufacturers will extend warranties on known issues. It’s possible it will be covered. I also note, the new Tiguan has a 6 year warranty which this car is younger than so I may have some room for negotiation.
I will return back to report back
I looked at changing the water pump myself but it seemed too involved for me right now having moved and changed jobs in the last 2 weeks. Also, here in the US manufacturers will extend warranties on known issues. It’s possible it will be covered. I also note, the new Tiguan has a 6 year warranty which this car is younger than so I may have some room for negotiation.
I will return back to report back
h0b0 said:
I dropped the car off at the dealer yesterday. They were confused as to why I didn’t just top up the coolant. I told them it will randomly be at the correct level independent of temperature.
The cooling system is sealed so it should not need topping up. As far as I am concerned, if the level falls then it is leaking somewhere and there must be an issue.Seems to me that VAG engines consume coolant and oil and it is seen as "normal". Personally I think a healthy engine should not loose coolant and should use minimal, if not zero oil between services. 1 litre of oil every 1000 miles being within tolerance is a joke.
h0b0 said:
I’m fairly sure it’s in there, just in the wrong place as the pump isn’t working.
If the coolant system isn't leaking (e.g. via headgasket, water pump, radiator, heater matrix etc.) then there is nowhere else for the coolant to go. There is no secret room for it to hide in whilst you check the level.It could be an airlock; if the air finally gets shifted the coolant level will drop. However if it keeps recurring then there is definitely a fault somewhere.
h0b0 said:
I’m fairly sure it’s in there, just in the wrong place as the pump isn’t working.
If the pump wasn't working the coolant system wouldn't be being pressurised and as such the coolant wouldn't run back to the reservoir when you remove the cap.The coolant level in the reservoir can vary by a couple inches depending upon the coolant temperature which is why it's best to check the level first thing in the morning when it's stone cold. That way you get consistency and work out how much coolant is being lost. Also if the pump wasn't pumping and no coolant was being circulated it would overheat. There is a secondary electric coolant pump that runs on after switch off for a period to prevent heatsoak but I doubt that can shift enough coolant by itself to prevent overheating if the main pump failed.
I've went through a similar scenario with a Golf R32 which developed a pin hole in the engine block which allowed coolant to escape. It was a real bugger to track down but thankfully VW replaced the engine under warranty.
It's not unknown for the pressure relief valve to be faulty on the coolant cap and for that to cause a little coolant loss.
Edited by cuprabob on Wednesday 27th June 16:28
GreenV8S said:
cuprabob said:
If the pump wasn't working the coolant system wouldn't be being pressurised and as such the coolant wouldn't run back to the reservoir when you remove the cap.
I can't make any sense of that.cuprabob said:
GreenV8S said:
cuprabob said:
If the pump wasn't working the coolant system wouldn't be being pressurised and as such the coolant wouldn't run back to the reservoir when you remove the cap.
I can't make any sense of that.The pump doesn't pressurise anything, it circulates the coolant.
The system is pressurised by the increase in temperature in the coolant system.
This pressure will naturally expand all hoses slightly and compress any entrapped air.
When you depressurise the coolant system (remove the pressure cap) this compressed air & expansion of the hoses makes the fluid level appear to increase at the expansion tank, even though the volume of fluid in the system has not changed significantly.
This is why ALL expansion tanks have a cold fill level stamped on the side.
The system is pressurised by the increase in temperature in the coolant system.
This pressure will naturally expand all hoses slightly and compress any entrapped air.
When you depressurise the coolant system (remove the pressure cap) this compressed air & expansion of the hoses makes the fluid level appear to increase at the expansion tank, even though the volume of fluid in the system has not changed significantly.
This is why ALL expansion tanks have a cold fill level stamped on the side.
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