Coolant leak 2014 180hp, run out of ideas

lloydbuck

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Hi,

I've recently found this forum and am hoping that someone can help please!

I have a 2014 A3 tdi 180hp which I love, and am very reluctant to let go, but don't know what else to do at this point. It has 115k miles on the clock (I've driven 90k of those), and has had a lot spent on it mechanically in the last couple of years replacing worn out parts. Last month I got the red no coolant warning, so took it into my garage to be looked at. I've been using this garage of over a decade, their chief engineer was trained by Audi and left the main dealer to set up his own garage. He trained his own mechanics, and sadly passed away some years ago. They have been fantastic with the car over the years and I trust them.

Upon examination, they determined that there was a leak on the water pump, and this was actually due for replacement anyway, along with the timing belt. I subsequently paid to have this done (£700).

Unfortunately, this didn't fix the issue. I took the car back and they pressure tested the coolant system and couldn't find anything. They suggested the cap on the coolant tank might not be fitting tightly enough, so replaced that. They also suggested that there may have been air in the system from when the new water pump was fitted. There was no charge for carrying out the tests and they asked me to monitor.

The leak continued. I took the car back last week where they again pressure tested it, and could find no leak. They replaced the coolant header tank in case this was the issue. Again, no charge. I was again asked to monitor the situation. If the leak continued, they think it is an internal leak somewhere.

There is still a leak. There is no puddle under the car when it is parked, so no signs of an external leak. There is no white smoke coming from the exhaust to suggest that it is burning coolant off that way. There are no deposits around the oil cap to suggest that it is leaking into the oil. The heater is working normally, and the garage also tested this. There doesn't seem to be any damp around the passenger footwell.

The car has just lost a full tank of coolant in around 120 miles, so it's not insubstantial. It has now lost around 3 tanks of coolant since this issue started and I'm concerned about where it is going! The mechanics are at a loss, and have said that if it's internal, it may be the head gasket, but they would not know without starting to strip down the engine, which is likely to start costing huge amounts of money.

Can anyone shed any light on this or suggest what the problem may be?

Many thanks!
 
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Pressure tested over night?

Does it lose coolant after a good drive & sitting idle on the driveway?

Have they checked inside the cylinders for any signs?

Is there any condensation in the car more than you'd think o, if so then check the carpets for dampness, could be heated matrix fault.
 
Pressure tested over night?

Does it lose coolant after a good drive & sitting idle on the driveway?

Have they checked inside the cylinders for any signs?

Is there any condensation in the car more than you'd think o, if so then check the carpets for dampness, could be heated matrix fault.
Thanks for the reply.

It was pressure tested at the garage on both occasions;

It does not lose coolant at all sitting on the driveway, regardless of whether it has recently been driven or not;

I don't think the mechanics have looked inside the engine at all yet, they've just said it could be the head gasket, but I don't seem to have any other signs of that being the problem;

I don't think there is more condensation than normal. I've removed the mat by the passenger seat to check for dampness, and am not sure if the carpet is a little damp or just cold. I pressed some absorbent paper there to see if any moisture came up, but it didn't seem to.

I have been driving with the heater/ac on recently and it seems to have gone through the last tank of coolant very quickly, so I'm wondering if it could be the heater matrix, as others have reported this as the problem as well.
 
No heating problems? Is there warm air coming out of all the air outlets inside?
One problem with this 2.0 TDI is the heater radiator, which clogs up, causing the system to over-pressurise.
If your mechanic has already tried everything, this could be it.
The part costs less than 100€, if you're a bit of a handyman you can change it yourself.
 
No heating problems? Is there warm air coming out of all the air outlets inside?
One problem with this 2.0 TDI is the heater radiator, which clogs up, causing the system to over-pressurise.
If your mechanic has already tried everything, this could be it.
The part costs less than 100€, if you're a bit of a handyman you can change it yourself.
I've set the heater to HI and yes, there is warm air through all outlets. The mechanics have looked at the heater as when I collected it the first time, it was set to HI, and I never use this setting. Presumably, if I don't use the heater/air con, there is no coolant being sent through this system. Subsequently, if the car the doesn't lose coolant that points to the heater being the problem?

Having looked through a range of symptoms for different causes of coolant loss, it's not showing any other symptoms of head gasket failure or cylinder head problems, so I'm not convinced that it's leaking into the engine, which is at least something.