Mysterious Coolant Leak

[joel bint]

Hi all,

I have a 2014 Audi A3 8V 2.0 tdi (97k miles)

for around a year now I have had a pretty persistent Coolant leak in my car.  I have never been able to track down the route of the problem.

I have to refill my coolant around every 10 days as it quite literally disappears. I have taken it to multiple garages and even they couldn't find the problem, as all garages do, they quote you the most expensive job, replacing the head gasket (£900 just to strip the engine!) so I gave up with them. no internal leak, to residue within any part of the oil so I self-diagnosed that the head gasket was not the problem. 

the other day while driving i noticed my radiator kicked in, i decided to pull over, and to my surprise, I finally saw a puddle of coolant coming out from the actual reservoir. I don't think anyone would ever be happy to see a coolant leak, but I was buzzing. 😄

cut long story short, i still cannot identify where or what the problem is. I have total coolant loss, a burning smell coming from the tank itself,  no heat in my cabin, and back pressure in the system. My only thought is a blocked heater matrix but I know that is a labour-intensive job. i want to bleed my coolant system and flush my heater matrix to help me get to the problem. 

could someone be able to help me as i don't have much experience with cars and would like any insight on what it could be? Also, I would like to know how I flush my coolant system.

 

thanks in advance 

[cliffcoggin]

A frequent cause of invisible coolant loss is the EGR cooler. That you now have a visible loss from the reservoir might suggest the hole in the EGR cooler is now big enough to allow blow back. The only way to be sure is to remove the EGR cooler which I believe, as I have never done it, is a devil of a job.

[Magnet]

You may also like to eliminate the simple things first, and replace the reservoir cap with a good quality new one. 
Kind regards,

Gareth. 

[Stevey Y]

5 hours ago, joel bint said:

Hi all,

I have a 2014 Audi A3 8V 2.0 tdi (97k miles)

for around a year now I have had a pretty persistent Coolant leak in my car.  I have never been able to track down the route of the problem.

I have to refill my coolant around every 10 days as it quite literally disappears. I have taken it to multiple garages and even they couldn't find the problem, as all garages do, they quote you the most expensive job, replacing the head gasket (£900 just to strip the engine!) so I gave up with them. no internal leak, to residue within any part of the oil so I self-diagnosed that the head gasket was not the problem. 

the other day while driving i noticed my radiator kicked in, i decided to pull over, and to my surprise, I finally saw a puddle of coolant coming out from the actual reservoir. I don't think anyone would ever be happy to see a coolant leak, but I was buzzing. 😄

cut long story short, i still cannot identify where or what the problem is. I have total coolant loss, a burning smell coming from the tank itself,  no heat in my cabin, and back pressure in the system. My only thought is a blocked heater matrix but I know that is a labour-intensive job. i want to bleed my coolant system and flush my heater matrix to help me get to the problem. 

could someone be able to help me as i don't have much experience with cars and would like any insight on what it could be? Also, I would like to know how I flush my coolant system.

 

thanks in advance 

Hi its not a blocked heater matrix as that is only a bypass circuit, to my mind it seems more like a thermostat problem its sticking shut.

Steve.

[Magnet]

Hello Joel,

Does the coolant temperature reach 90 within a couple to 3 miles, and always hold at that through the rest of the (longish) journey? 
Kind regards,

Gareth. 

[joel bint]

13 hours ago, Magnet said:

Hello Joel,

Does the coolant temperature reach 90 within a couple to 3 miles, and always hold at that through the rest of the (longish) journey? 
Kind regards,

Gareth. 

hi Gareth, 

that is exactly what happens, the temp does not fluctuate at all

[joel bint]

18 hours ago, Magnet said:

You may also like to eliminate the simple things first, and replace the reservoir cap with a good quality new one. 
Kind regards,

Gareth. 

i have ordered a new reservoir and cap, Do you know how I can change it over while doing a coolant flush? i have no idea where the radiator cap is to drain the coolant

[joel bint]

16 hours ago, Stevey Y said:

Hi its not a blocked heater matrix as that is only a bypass circuit, to my mind it seems more like a thermostat problem its sticking shut.

Steve.

is this an expensive job? changing the thermostat 

[Magnet]

Why are you resorting to a coolant flush Joel? The reservoir cap is just a reservoir cap - unscrew it, and screw the new one on.

If the coolant temperature gauge is getting to 90 within about 3 miles, and more importantly, holding at that throughout a longish journey, then I wouldn’t expect the thermostat to be at fault - unless Stevey Y is of different opinion. 
Kind regards,

Gareth. 

[cliffcoggin]

47 minutes ago, joel bint said:

i have ordered a new reservoir and cap, Do you know how I can change it over while doing a coolant flush? i have no idea where the radiator cap is to drain the coolant

This does not make sense. You unscrewed the cap many times to refill the reservoir so you do know where it is.

I suggest you stop wasting money on new parts like a reservoir and thermostat until you have made a confident diagnosis. You have lived with the problem for a year so a few more days delay while we discuss the matter is of no consequence.

[Magnet]

Any progress or comment Joel? 

[joel bint]

On 11/23/2024 at 10:02 AM, Magnet said:

Any progress or comment Joel? 

We are waiting on a new cap, which has not yet been delivered. So, as of yet, there is no update on the diagnosis.

[joel bint]

On 11/18/2024 at 12:14 PM, cliffcoggin said:

This does not make sense. You unscrewed the cap many times to refill the reservoir so you do know where it is.

I suggest you stop wasting money on new parts like a reservoir and thermostat until you have made a confident diagnosis. You have lived with the problem for a year so a few more days delay while we discuss the matter is of no consequence.

My apologies, I meant the drain bolt. 

waiting on a new reservoir Cap, before I do anything else, I just thought it may be worth it to do a coolant flush to make sure there is not any air in the system

[Magnet]

No problem Joel,

Doing a coolant flush is certainly going to introduce more air into the system. 
Changing the cap will eliminate that as a possible offender. 

Never carryout two changes at the same time.

If you do, you won’t know which of the two was the culprit. 
Always change one thing and test. 

Kind regards,

Gareth. 

[joel bint]

quick update,

A new Cap arrived, only put it on last night so hopefully I see an improvement.

bit of good and bad news, 

The heat is back in the cabin, though it takes a very long while to warm up. However, I am now getting a clicking and popping sound, like it is coming from the dashboard. I have no idea what this could be, but when the clicking stops, I usually have a coolant loss indicator on my dash.