Coolant blown out from expansion bottle

shocks

Active member
Joined
Jan 22, 2020
Location
Perth AU
TDI
Golf MK6 2.0TDI (103KW CFFB) Comfortline, Golf MK7 2.0TDI Highline (CRBC 110KW), Passat Alltrack Wolfsburg Ed. 2.0TDI (DFHA 140KW)
950 pounds, wow, that's a lot, VW service is a rip off. Technically the flushing etc, etc, is required by the book but you could just empty the old coolant and replace it (3 x 1.5L bottles of concentrated is about 100 aussie dollars here. So say 50 pounds). A genuine heater core would be about 150 pounds. However, if the other mechanic is doing all this and a full flush for 420 pounds then it's probably not too unreasonable. There are no special VAG tools required for this job but if you don't have the normal vacuum filling tools required it's not a practical DIY job. The computer bit is just a sequence that runs the engine at different speeds and also the various electric coolant pumps to get air out of the system, it only takes about 15 mins and I'm sure most good scan tools or VCDS can do it (I used ODIS).

As for the sludge they claimed to see, I'd say this is BS, my matrix was partially clogged and after collecting my old coolant in a clear container very little debris has settled out. The heater matrix is obviously just a bad design and the EGR Valve coolant circuit design is even worse by relying on passage through the restrictive matrix.
 
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shocks

Active member
Joined
Jan 22, 2020
Location
Perth AU
TDI
Golf MK6 2.0TDI (103KW CFFB) Comfortline, Golf MK7 2.0TDI Highline (CRBC 110KW), Passat Alltrack Wolfsburg Ed. 2.0TDI (DFHA 140KW)
So, what is the total amount of coolant needed? I don't seem to find it anywhere.
The filling sequence in the Golf TDI workshop manual (https://imgur.com/3cLSN1L) tells you to have at least 8 litres of pre-mixed coolant in the "expansion tank" of VAS 6096. It's not worded very well, they mean the reservoir you'll use to fill.

I initially got about 7.5 litres to go in on my first vacuum fill, and added about another 300 - 400 ml during the subsequent top ups after the bleed sequence so the 8 litres was pretty close to the mark.

If you buy 3 x 1.5 litres bottles of G13 you'll be good for 9 litres when mixed 50/50. You can't get any more in there than the engine coolant system can take so it's not like filling other fluids. If you do put too much in, it'll only be a small amount and you can just remove it from the bottle.
 

minu94

Member
Joined
Nov 12, 2019
Location
Bucharest, Romania
TDI
2.0 TDI 184 Cupa Leon 5F
So, today I removed the old heater core and got the new one installed. Also changed the coolant. What I found home, whilst putting water with pressure inside the old heater core surprised me, but not in a good way. The next few days I will try to go on a longer trip to see if the coolant still gets out.
Pics:
https://ibb.co/r6DXF2t
https://ibb.co/dPKGgpv

LE: There were more debris than seen in the pic.
Also, before trying to clean it, water was barely coming out. After some minutes of attacking the heater core from both sides, it started to flow more easily. I have videos of that if someone is interested
 
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nathanso

Veteran Member
Joined
Mar 31, 2019
Location
Redwood City, CA
TDI
2015 GSW TDI S 6M
So, today I removed the old heater core and got the new one installed. Also changed the coolant. What I found home, whilst putting water with pressure inside the old heater core surprised me, but not in a good way. The next few days I will try to go on a longer trip to see if the coolant still gets out.
Pics:
https://ibb.co/r6DXF2t
https://ibb.co/dPKGgpv
LE: There were more debris than seen in the pic.
Also, before trying to clean it, water was barely coming out. After some minutes of attacking the heater core from both sides, it started to flow more easily. I have videos of that if someone is interested
Was your coolant reservoir's silicate bag intact or ruptured?
 

mm-rocco

Well-known member
Joined
Jul 31, 2019
Location
Netherlands
TDI
MK7 GTD 2016
Hi All, my coolant problem is finally solved ! I started with replacing two leaking hoses, after a month i replaced the heater core, ik drove about 8000km and the coolant problem was back. Then we replaced the EGR-Cooler and that did not solve anything. Two weeks ago the head gasket was replaced and the car is fine. There is absolutely no pressure on the coolant system anymore. I drove about 1200km now.
 

minu94

Member
Joined
Nov 12, 2019
Location
Bucharest, Romania
TDI
2.0 TDI 184 Cupa Leon 5F
Finally, glad to hear that mm-rocco. The head gasket will be my next step also. What exactly were your symptoms?
Also, did they skimmed the cylinder head? What else did you replace in the engine, only the head gasket?
 

mm-rocco

Well-known member
Joined
Jul 31, 2019
Location
Netherlands
TDI
MK7 GTD 2016

Tjockhult

New member
Joined
Mar 5, 2020
Location
Oxfordshire UK
TDI
Seat Leon 2.0 TDI FR 2014
I had the coolant blow out and no heating in the cabin about 6 weeks ago. I took the car 2014 Seat Leon 2.0 TDI to a Seat dealer for cambelt and coolant pump replacement as it was due. They did diagnose heater matrix replacement at a cost of £ 910! So I asked other grease monkeys and one said head gasket - £ 1,100 or bent cylinder head - £ 2,200. I did not believe him and managed to rent a Combustion Leak Detector for £10 from a local auto factor. And I could prove to myself that he was wrong. Read the workshop manual and realised it is quite complex to replace the heater matrix - hence the high cost and 5 hours of labour. So I went back to the dealer and asked them to change the heater matrix. That was two weeks ago and we have driven 700 miles / 1100 km with a mix of local roads and more than one hour on motorways – absolutely fine. I also have two years parts and labour warranty from the dealer.

I did say to the dealer that another garage had diagnosed head gasket or cylinder head “No way, you’d be loosing coolant very quickly if that was the problem”. The cooling system on the VAG MQB diesel is quite complex with several pumps and also the EGR. Whatever muck is in the system – from either blown silica bag, or broken heater matrix (failing due to poor QA from supplier) – appears to be damn hard to get rid of, hence the 5 hours. It may well be that for those of you who have replaced the heater matrix yourself, or had a non dealer replacing it, you still have blockages in the cooling system that you have been unable to get rid of. I’d recommend a VAG dealer heater matrix replacement before you throw monies on cylinder heads etc.
 

SkilledMilk

Member
Joined
Mar 31, 2018
Location
Glasgow
TDI
Leon MK3 (184) 2013
Glad your issue is sorted, with a bit of piece of mind with the warranty. Others arrived at the same conclusion here that the head gasket was unlikely an you'd be losing coolant all the time, not just after a regen.

Keep us updated (hopefully no return of symptoms!). I replaced mine myself August last year, and ~10,000 miles driven since, not a drop lost.

Glad that for most on this forum, the issue has been solved with a relatively minor fix. Its not fun having to constantly drive around with a bottle of coolant to top up!
 

SkilledMilk

Member
Joined
Mar 31, 2018
Location
Glasgow
TDI
Leon MK3 (184) 2013
Hi All, my coolant problem is finally solved ! I started with replacing two leaking hoses, after a month i replaced the heater core, ik drove about 8000km and the coolant problem was back. Then we replaced the EGR-Cooler and that did not solve anything. Two weeks ago the head gasket was replaced and the car is fine. There is absolutely no pressure on the coolant system anymore. I drove about 1200km now.
Good to hear you're finally fixed! Unfortunate it was the end game nobody wants to hear.
 

minu94

Member
Joined
Nov 12, 2019
Location
Bucharest, Romania
TDI
2.0 TDI 184 Cupa Leon 5F
I have a coolant exhaust gas leak detector at home and I will be testing these days. I will come back here with the results after I do it. Mine seems to throw out coolant at high loads or sustained high speed.
@mm-rocco, when they did the head gasket replacement, did they also skimmed the head?
 
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mm-rocco

Well-known member
Joined
Jul 31, 2019
Location
Netherlands
TDI
MK7 GTD 2016
I have a coolant exhaust gas leak detector at home and I will be testing these days. I will come back here with the results after I do it. Mine seems to throw out coolant at high loads or sustained high speed.
@mm-rocco, when they did the head gasket replacement, did they also skimmed the head?

Nope, they did not skim the head.
 

Tjockhult

New member
Joined
Mar 5, 2020
Location
Oxfordshire UK
TDI
Seat Leon 2.0 TDI FR 2014
So, this is the result after checking for exhaust gases in coolant. It’s pretty clear that it tested positive.
Before and after:
https://ibb.co/BgXpXmw
https://ibb.co/6YR8PK7
I'm not a car mechanic but when I did my test I found the liquid stayed blue in the upper chamber. You appear to have a colour change... However it seemed really important to have a very good seal on to the expansion tank - any air in to the tester may give a false reading. I would test and test and test again. I tested probably 10 times before I was happy.
 

mm-rocco

Well-known member
Joined
Jul 31, 2019
Location
Netherlands
TDI
MK7 GTD 2016
I drove about 5000km now with the new gasket and all previous problems disappeared ! I am very happy ! Hopefully we keep this topic alive so others can benefit from it !
 

Kamilecki166

New member
Joined
Feb 21, 2020
Location
Poland
TDI
CUNA EA288
Hello everyone.

My problem has been solved. Wasn't cheap, but is SOLVED :)

The problem was on the timming belt coolant pump side, but from the beginning ..
The pump has a flange that restricts the flow of fluid, if you do not change the fluid on time, or replace it with a non-G13 one, you may have problems with blurring flange (it can get stuck).
In my case, it caused the engine head to overheat, and to generate steam that couse air buble in matrix. (in extreme cases it may also cause damage to the silicate bag).
At the worst moment, the engine stopped starting because it blew out the gasket under the engine head and the coolant got into cylinder 3, blocking the possibility of crankshaft rotation.
Fortunately, the workshop to which I finally took the car had 3 such cases that at a mileage of about 100,000Km the flange was blocking and the coolant was disappearing in the form of steam. (for me it was 108,000Km)
I also learned that sometimes replacing the fluid with a new one can temporarily help in the operation of the flange and restore its efficiency.

Video I've made : rolleyes:
https://www.youtube.com/watch?v=wCwcaq0pat0&feature=youtu.be

from 0: 50s you can see the problem, the flange should return to the position in which the pump propeller is visible.

(and yes ... that was my foot..)

Sorry for the long entry.

Regards Kamil.
 
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RIP TDI

Top Post Dawg
Joined
Feb 16, 2000
Location
Santa Barbara, CA
TDI
'15 GSW SE 6MT, '01 Golf GLS 5MT, '96 Passat variant
Hello everyone.

My problem has been solved. Wasn't cheap, but is SOLVED :)

The problem was on the timming belt coolant pump side, but from the beginning ..
The pump has a flange that restricts the flow of fluid, if you do not change the fluid on time, or replace it with a non-G13 one, you may have problems with blurring flange (it can get stuck).
In my case, it caused the engine head to overheat, and to generate steam that couse air buble in matrix. (in extreme cases it may also cause damage to the silicate bag).
At the worst moment, the engine stopped starting because it blew out the gasket under the engine head and the coolant got into cylinder 3, blocking the possibility of crankshaft rotation.
Fortunately, the workshop to which I finally took the car had 3 such cases that at a mileage of about 100,000Km the flange was blocking and the coolant was disappearing in the form of steam. (for me it was 108,000Km)
I also learned that sometimes replacing the fluid with a new one can temporarily help in the operation of the flange and restore its efficiency.

Video I've made : rolleyes:
https://www.youtube.com/watch?v=wCwcaq0pat0&feature=youtu.be

from 0: 50s you can see the problem, the flange should return to the position in which the pump propeller is visible.

(and yes ... that was my foot..)

Sorry for the long entry.

Regards Kamil.
Dealers are replacing the variable-flow pumps with conventional non-variable pumps without the shroud (flange). I assume your workshop did that, too?
 

dejvid

New member
Joined
Oct 10, 2019
Location
Czech republic
TDI
GVII Variant 2,0tdi
Hi, did anyone make a change of heat core by myself?
Without system venting/flushing.
Or I would rather take it to car service?
 

SkilledMilk

Member
Joined
Mar 31, 2018
Location
Glasgow
TDI
Leon MK3 (184) 2013
Hi, did anyone make a change of heat core by myself?
Without system venting/flushing.
Or I would rather take it to car service?
I changed mine myself, although it might be a little more difficult on left hand drive cars as the access to the core will be in the drivers footwell not the passengers.

I didn't flush the system but the car went in for service a week after I changed the core and the coolant was flushed then, but by the garage. maybe tie in your own replacement with a service for your own peace of mind?
 

DowlingColm

New member
Joined
Jul 9, 2020
Location
Ireland
TDI
2014 Golf GTD 184PS CUNA
2014 GTD Coolant loss through expansion tank

I've recently bought myself a 2014 Golf GTD 184PS CUNA engine. I've been having similar issues to what's in this thread. I was lucky to find this and it has been a real help in understanding whats happening, however I haven't had much luck in solving my particular issue. Coolant gauge never moves from 90. Oil temp starts to climb on motorway and particularly when driving hard it can get to temperatures in excess of 120 which I'm not comfortable with. Coolant expansion tank seems to be over pressurising, when I turn the car off I can sometimes hear it hissing. During and after a DPF regen coolant starts escaping the tank and I can see it all over the side of my car after driving. I have replaced the timing belt and water pump, the cabin heater matrix and I have flushed the radiator twice. I'm planning to replace the electric aux. water pump for the cabin matrix because I can hear it grumbling and gargling. I'm under the impression that there is good flow in the matrix but the pump isn't up to the task. In my opinion its either this pump that's the issue or insufficient flow in the oil cooler. I have another oil cooler and I will try changing it after I get some new gaskets for it, I reckon there's no point changing the whole filter housing, I'll just try and flush it and give it a look over. If the radiator was blocked I would surely see the gauge rising to 110 or 120 and even get an engine overheat error so I can't imagine that's the case. I'm just looking for an opinion from you guys.

My issue has to be either electric coolant pump for matrix or a blocked oil cooler. I've looked at the intercooler and there seems to be good flow from that too, might be worth flushing the radiator for this circuit too but I'm not too worried about it because it doesn't get hot really. I can't come up with any other possible issues. There's no mixing of oil or coolant or no hard start issue indicating water in a cylinder.
 

mm-rocco

Well-known member
Joined
Jul 31, 2019
Location
Netherlands
TDI
MK7 GTD 2016
I've recently bought myself a 2014 Golf GTD 184PS CUNA engine. I've been having similar issues to what's in this thread. I was lucky to find this and it has been a real help in understanding whats happening, however I haven't had much luck in solving my particular issue. Coolant gauge never moves from 90. Oil temp starts to climb on motorway and particularly when driving hard it can get to temperatures in excess of 120 which I'm not comfortable with. Coolant expansion tank seems to be over pressurising, when I turn the car off I can sometimes hear it hissing. During and after a DPF regen coolant starts escaping the tank and I can see it all over the side of my car after driving. I have replaced the timing belt and water pump, the cabin heater matrix and I have flushed the radiator twice. I'm planning to replace the electric aux. water pump for the cabin matrix because I can hear it grumbling and gargling. I'm under the impression that there is good flow in the matrix but the pump isn't up to the task. In my opinion its either this pump that's the issue or insufficient flow in the oil cooler. I have another oil cooler and I will try changing it after I get some new gaskets for it, I reckon there's no point changing the whole filter housing, I'll just try and flush it and give it a look over. If the radiator was blocked I would surely see the gauge rising to 110 or 120 and even get an engine overheat error so I can't imagine that's the case. I'm just looking for an opinion from you guys.

My issue has to be either electric coolant pump for matrix or a blocked oil cooler. I've looked at the intercooler and there seems to be good flow from that too, might be worth flushing the radiator for this circuit too but I'm not too worried about it because it doesn't get hot really. I can't come up with any other possible issues. There's no mixing of oil or coolant or no hard start issue indicating water in a cylinder.

I replaced EGR, Cabin Heater and this did not solve the problem. After replacing the head-gasket all my problems disappeared ! I drove about 15.000 km since.......
 

Adyzds

Member
Joined
Aug 29, 2019
Location
Romania
TDI
Golf 7 2.0 TDI
Just left my car to the service to replace the heater core.
Went to the best service in town and don't know how well I explained, but the guy said it doesn't make any sense and he still thinks its the head gasket.

A simple explanation WOULD be that the heater core gets clogged and the water boiled inside of it when DPF regen. Am i right?

I've lost almost no coolant from last year. When DPF regenerates, I was turning on heat at max (only time when my car gives heat from the right passenger side)
 

SkilledMilk

Member
Joined
Mar 31, 2018
Location
Glasgow
TDI
Leon MK3 (184) 2013
Just left my car to the service to replace the heater core.
Went to the best service in town and don't know how well I explained, but the guy said it doesn't make any sense and he still thinks its the head gasket.

A simple explanation WOULD be that the heater core gets clogged and the water boiled inside of it when DPF regen. Am i right?

I've lost almost no coolant from last year. When DPF regenerates, I was turning on heat at max (only time when my car gives heat from the right passenger side)
If you're only getting heat from one side, then the core is most likely partially blocked. As others have mentioned, they still had issues after heater core replacement and it turned out to be the head gasket. However, it seem like most have had success after changing only the heater core.

Blowing the heater on max during regen might make just enough difference to the coolant temperature that you prevent it from boiling over (it is just a small radiator after all).
 

Adyzds

Member
Joined
Aug 29, 2019
Location
Romania
TDI
Golf 7 2.0 TDI
If someone is interested in seeing how heater matrix looked from inside: https://imgur.com/a/Ypc2Fw0

I suspect it was more clogged in the past. I think I skipped turning heat on for last 500km and it didn't lost coolant. Will see how it acts with the Nissens heater
 
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