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Loss of Coolant from Expansion Tank and i don't know why???

Angelo George

Active Member
Jul 11, 2018
8
0
Hi to all,

I am in urgent need of help to solve a coolant loss problem on my 2013 Seat Leon diesel 184!!

Ever since I bought the car 6 months ago i keep getting a low coolant warning message every now and then. When i check the expansion tank it is completely empty and it looks like all the coolant is around the tank. This coolant loss could happen once a month or even twice a week!! I replaced the expansion tank and the cap but to no avail. My mechanic did a pressure test and that came back fine. There is no contamination in either the coolant or the oil. There is no smoke out of the exhaust. I have no wet carpets or damp in the cabin and i have no visible leaks as the car is parked in a garage most of the time. The one thing i noticed is that the car takes quite a long time (in my eyes) to warm up (a good 15 mins to get to 90 degrees under normal driving). I always check the coolant temperature and it never goes over 90. This is driving me crazy, my mechanic has been no help, and I could really use some help.

I don't want to go down the path of replacing perfectly good parts if it won't solve my problem. Any ideas or if the same this has happened to you would be GREATLY appreciated!!

BTW my car is a 2013 Seat Leon FR 2.0 TDI 184PS.
 

paddy6789

Mk3 Cupra R
Staff member
Moderator
Aug 31, 2016
1,565
973
Preston, Lancs
Have you had the water pump checked? Mine done something similar (not as bad as yours) but apparently it’s a common fault on the Leon Mk3.


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Angelo George

Active Member
Jul 11, 2018
8
0
I didn't get the pump checked out. The car is due for a service soon so will get the mechanic to check it out. Thanks and i will post any updates
 

Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
5,086
2,575
No it’s blowing out of the relief valve in the cap seems to be after it’s done a regen of the DPF
How low does the level drop? You got anything you can check coolant temperature with rather than using the guage? Do you top it back with coolant (G12) or water?
 

jamie_

Active Member
Dec 22, 2010
183
2
Cumbria
How low does the level drop? You got anything you can check coolant temperature with rather than using the guage? Do you top it back with coolant (G12) or water?
The level will stay fine for maybe a week at a time (the car does quite a lot of miles a week) then seems to dump the header tank out when engine is off.

Had a compression test done on the cooling system and it stayed solid. Also replaced the cap just in case the relief had started to fail

The system has been topped up with water at the moment but I do have some new G13 to put back in which I bought today
 

Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
5,086
2,575
If it's coming out of the relief valve. Either the coolant is boiling at a lower temp (pressure leak, air in system, ratio of water to coolant too high) or the car is getting hot enough to boil the coolant. Are the front fans working? Maybe look at getting a cheap odb phone connector to monitor temps. The guage shows normal past 100+ degrees I believe. Do you get bubbles in the expansion tank?
 

Angelo George

Active Member
Jul 11, 2018
8
0
The level will stay fine for maybe a week at a time (the car does quite a lot of miles a week) then seems to dump the header tank out when engine is off.

Had a compression test done on the cooling system and it stayed solid. Also replaced the cap just in case the relief had started to fail

The system has been topped up with water at the moment but I do have some new G13 to put back in which I bought today
 

Angelo George

Active Member
Jul 11, 2018
8
0
I still have the same problem!! Sooo annoying. I checked water pump ,compression test and practically everything under the sun besides changing engine. Although mine doesn’t do it once a week more like once a month or every 1500 miles. I have the exact same symptoms as you Jamie. Once I get the warning light for coolant my expansion tank is drenched in coolant. I have g12+ coolant in at the mo. It’s all leaving the pressure release and I changed the expansion tank and the cap. I have noticed it will loose around half the expansion tanks contents at a time. I’ve just got used to filling it up around once a month but this is not a solution!!!! Any ideas from the community will be appreciated!!
 

jamie_

Active Member
Dec 22, 2010
183
2
Cumbria
If it's coming out of the relief valve. Either the coolant is boiling at a lower temp (pressure leak, air in system, ratio of water to coolant too high) or the car is getting hot enough to boil the coolant. Are the front fans working? Maybe look at getting a cheap odb phone connector to monitor temps. The guage shows normal past 100+ degrees I believe. Do you get bubbles in the expansion tank?
Yeah I believe the coolant must be boiling in the system somewhere. When I opened the cap the other day when I noticed the level low. (Not noticed this before it’s usually fine or gone) it bubbled and level then had a rise of about 5mm saying there is air in the system. But not sure where it is coming from. Not noticed the fans working however the car doesn’t usually have them running unless turned off during a regen cycle of the dpf. The coolant gauge never goes over 90•c
 

Angelo George

Active Member
Jul 11, 2018
8
0
I still have the same problem!! Sooo annoying. I checked water pump ,compression test and practically everything under the sun besides changing engine. Although mine doesn’t do it once a week more like once a month or every 1500 miles. I have the exact same symptoms as you Jamie. Once I get the warning light for coolant my expansion tank is drenched in coolant. I have g12+ coolant in at the mo. It’s all leaving the pressure release and I changed the expansion tank and the cap. I have noticed it will loose around half the expansion tanks contents at a time. I’ve just got used to filling it up around once a month but this is not a solution!!!! Any ideas from the community will be appreciated!!
Jamie how long does ur car take for water temperature to reach 90 degrees? Mine takes a good five minutes. How long does urs take? My other car only needs around 1-2 mins and I’m in Cyprus in 35 degrees heat!!!! So another option might be to change the thermostat.
 

jamie_

Active Member
Dec 22, 2010
183
2
Cumbria
Jamie how long does ur car take for water temperature to reach 90 degrees? Mine takes a good five minutes. How long does urs take? My other car only needs around 1-2 mins and I’m in Cyprus in 35 degrees heat!!!! So another option might be to change the thermostat.
Hi Angelo

The car usually takes a while to warm up this hasn’t really changed since the problem started. The 2.0tdi engines are really thermally efficient.

I have thought about the thermostat however I would expect to have overheating issues if that was at fault.
 

Angelo George

Active Member
Jul 11, 2018
8
0
Hi Angelo

The car usually takes a while to warm up this hasn’t really changed since the problem started. The 2.0tdi engines are really thermally efficient.

I have thought about the thermostat however I would expect to have overheating issues if that was at fault.
True! My eyes are constantly on the water temp and it never goes over 90. I thought about the water boiling under 100 due to pressure issues but I did 2 compression tests and both came back fine
 

Legojon

I only wanted a remap
Staff member
Moderator
Jul 7, 2015
5,086
2,575
Is that from the gauge? Cause the guage is designed not to panic the driver and displays 90 from 80 up to 100ish. So worth checking it with an obd reader.
 
Jan 20, 2019
6
0
Hi to all,

I am in urgent need of help to solve a coolant loss problem on my 2013 Seat Leon diesel 184!!

Ever since I bought the car 6 months ago i keep getting a low coolant warning message every now and then. When i check the expansion tank it is completely empty and it looks like all the coolant is around the tank. This coolant loss could happen once a month or even twice a week!! I replaced the expansion tank and the cap but to no avail. My mechanic did a pressure test and that came back fine. There is no contamination in either the coolant or the oil. There is no smoke out of the exhaust. I have no wet carpets or damp in the cabin and i have no visible leaks as the car is parked in a garage most of the time. The one thing i noticed is that the car takes quite a long time (in my eyes) to warm up (a good 15 mins to get to 90 degrees under normal driving). I always check the coolant temperature and it never goes over 90. This is driving me crazy, my mechanic has been no help, and I could really use some help.

I don't want to go down the path of replacing perfectly good parts if it won't solve my problem. Any ideas or if the same this has happened to you would be GREATLY appreciated!!

BTW my car is a 2013 Seat Leon FR 2.0 TDI 184PS.
Did u get coolant leak fixed and what was the problem
 

Angelo George

Active Member
Jul 11, 2018
8
0
After all these months and no nearer to a solution. I've just kinda learned to live with it. It's not doing it as ofter as usual now, usually around every three months (5000 miles) so just top up the expansion tank when it does. Although I can kind of guess when it does it now. Ive noticed that if the car loses boost (doesn't feel as torquey as it should) the coolant overflow occurs then and after a top up its back to normal. R U having similar issues?
 
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