Coolant blown out from expansion bottle

andreykutyaev

New member
Joined
Nov 16, 2017
Location
Adelaide, Australia
TDI
Mk7 Golf 2.0 TDI
Hi all, decided to share my pain with VW community after ~8 months of troubleshooting by VW (Australia). 2013 Mk7 Golf 110TDI is pushing coolant out from the surge tank. Looks like gases enter the jacket under load, accumulate and then rush up to expansion bottled causing it to overflow - overflow pipe is tiny and most of coolant is blow out through the cap threads and sprays around under the bonnet. Done so far to no effect by VW: replaced water pump, multiple cooling circuit pressure tests, replaced expansion bottle, replaced cylinder head c/w gaskets etc., replaced EGR cooler, replaced intercooler, performed engine compression test, replaced some weeping rubber hose. Any idea is appreciated. Love the car but got quite frustrated by now. Few more points: never ever had overheating or gauge temperature moving beyond 90degC; following each "blow out" can clearly hear "hissing" noise coming from the heater core suggesting pockets of gas travelling through the system.
 

Mike_04GolfTDI

Top Post Dawg
Joined
Nov 19, 2003
Location
Richmond, BC, Canada
TDI
Mine: 2019 Golf R DSG, Wife's: 2015 Golf Comfortline TDI
They've replaced everything I would have suggested.

Aside from parts that have already been replaced, I can think of no other parts of the engine in which pressurized intake or combustion gasses may be forced into the cooling system, except for the engine block.

So, they just need to pop a new engine in there and you should be fine.
 

Ol'Rattler

Top Post Dawg
Joined
Jul 3, 2007
Location
PNA
TDI
2006 BRM Jetta
It sure sounds like they were just randomly replacing perfectly good parts.

I had a similar problem with a Chevy Cavalier we had bought new which was that it slowly leaked coolant somewhere. Because of actual leaks I found I replaced the radiator, heater core and water pump. The car still leaked coolant with no visual signs of leaks.

I was at the Chevy dealers parts counter and explained my problem to the parts guy and he said, I know just what you need and came back with this: https://www.ebay.com/i/322619188336?chn=ps&dispctrl=1 Apparently, GM cannot build a leak free engine and so instead they put it in all of their new cars prior to delivery.

Well, actually, the stuff works pretty well and does not plug the heater core like most stop leak products do. If you try it, just don't tell the dealer..................
 

vortexhacker

New member
Joined
Dec 5, 2017
Location
Spain
TDI
2.0 184
Hello, I have a seat Leon 184 and I have the same problem and we are several more affected in Spain. I have replaced the thermostat and the electric pump of the heating circuit. nothing has solved the problem.
I will try to change the other electric pump.
 

andreykutyaev

New member
Joined
Nov 16, 2017
Location
Adelaide, Australia
TDI
Mk7 Golf 2.0 TDI
Update

Thanks to all for support. Car was with VW for more than a month, got it back and...bang, coolant is out from expansion bottle and heater stopped working (could hear hammering behind infotainment panel). Back with VW - they say heater matrix partially blocked and that is causing troubles I have. I don't understand mechanics behind it though. I still believe combustion gas breaks through somewhere, that can't be detected by pressure test or CO/CO2 tester. Any thoughts? Thanks!
 

turbobrick240

Top Post Dawg
Joined
Nov 18, 2014
Location
maine
TDI
2011 vw golf tdi(gone to greener pastures), 2001 ford f250 powerstroke
The mk7's have a pretty complex cooling circuit/s. There are cheap litmus type test kits that test for combustion by products in the coolant. Though, I think it would be pretty apparent visually. I'd just let them replace the heater core if it's covered by the warranty.
 

MihaK

New member
Joined
Feb 7, 2018
Location
Slovenia
TDI
Golf VII 2.0TDI Variant
Hi,
I have exactly the same problem for over a year now.
I have for a fact got a bit deeper into symptoms...

It happens only when car is doing active DPF regeneration and at the same time driving on a highway with medium speeds (100-110 kph).
It never overflowed if it was pushed hard on a mountain pass road (120°C+ oil temp) - I excluded head gasket. I allways get a alarm next morning when I come home from a long trip on a highway. Although when it's doing regeneration in normal urban speeds it never overflows.

I had car at a VW dealer and they said there was a too agresive coolant (!?) inside, so they cleaned it, replace it with fresh G13 and bleed, but after 6 months problem was back.
Maybe it was the result of good bleeding it lasted so long.
Previously I had expansion tank and cap replaced also.


So I have few ideas (when doing dpf regen):
1. the cooling fan doesn't turn on at the right time (if braking from 130 to under 100kph on highway) - causing it to boil somewhere in system.
2. something to do with thermostate and therefore failing to cool it sufficiently during highway regen.
3. most recently figured out I might have a clogged cabin heater, since sometimes cabin doesn't get warm for an hour or so, but sometimes works fine (could even be air in heater element?) - I haven't found reasonable connection with the problem yet.
4. some sensor is giving false readouts about coolant temperature (dashboard gauge never go over 90°C) and causing it to boil somewhere.

Does your coolant look "rusty"? I read somewhere that is the sign of overheated coolant and that sediment can cause cabin heater to clog.

Greetings from Slovenia!
 

MihaK

New member
Joined
Feb 7, 2018
Location
Slovenia
TDI
Golf VII 2.0TDI Variant
Hi,
have you figured this out yet?

I had a small overflow again today. When I heard my car was in active regen (fan runing, idle rpm@1100), I drove around a bit in order to let it finish.

When I noticed the RPMs dropped to normal (finished regeneration) I stopped and went out, popped the hood to check if there is any spill - none. When I was closing the lid I heard the fan stopped (or went to lower power - below hearing it when engine is running). Then I drove away and heard like air going trough pipes under dashboard or in front of firewall / below the windshield.
I went out and checked coolant again - and there it was - fog coming out of overflow tube and liquid around expansion bottle.
My guess is that those overflows happen right after regeneration while engine is still hot, but cooling system turns back to normal and it boils somewhere in circuit. The gauge on dashboard stayed perfectly on 90 degree as usually.

If anyone have some ideas, please help!
 

740GLE

Top Post Dawg
Joined
Aug 19, 2009
Location
NH
TDI
2015 Passat SEL, 2017 Alltrack SE; BB 2010 Sedan Man; 2012 Passat,
I wonder if you're noticing clogged heater cores and the excessive temps of egr is boiling the coolant and is being pushed out.
 

MattGrizzley

New member
Joined
Nov 15, 2018
Location
Melbourne
TDI
2013 Golf mk7 2.0 tdi
Has anyone had any luck with this issue I have the exact issue and VW can’t find the cause. I have replaced the water pump, surge tank and some hoses.
 

MihaK

New member
Joined
Feb 7, 2018
Location
Slovenia
TDI
Golf VII 2.0TDI Variant
I'm also thinking of partialy clogged heatercore - after the regeneration is finished, the EGR opens and hot air from DPF blows trough EGR cooler, where it boils because water is not circulating fast enough trough heater matrix.

Didn't change it yet, because VW dealership said its at least 2k eur for repair.

Does anyone know if you can get heater core out without removing entire dashboard?
 

Mario701

New member
Joined
Feb 10, 2019
Location
australia
TDI
VW Golf VII 2.0TDI
Hi guys,
i have very same problem with my VW Golf VII 2.0TDI (2013),
just replaced Coolant Tank+Cap, water pump+gasket..we also did some pressure tests (results: negative)..but the coolant keeps overflowing through Tank Cap and sprays under coolant tank. But i gotta say, it doesn't happen after every drive..
For example:
I topped up the coolant after replacing water pump, have done 400km, looked perfectly fine, thought for a second that the problem had been solved, but did 1 more trip, and here it comes again..coolant overflows again...
Next step, at least what mechanic told me, is Head gasket...
Have you guys got some ideas?
I am really getting frustrated, because nobody has figured out what is causing the problem so far..otherwise, the car is brilliant, done 115,00kms..never had any issues...
Any advice?
thanks, Mario
 

bigb

Veteran Member
Joined
Dec 15, 2018
Location
Arizona
TDI
2015 Sportwagon S
Sorry no help here but has anyone noticed all these cars are from the general areas of England, Spain and Australia?
 

MihaK

New member
Joined
Feb 7, 2018
Location
Slovenia
TDI
Golf VII 2.0TDI Variant
Mine was imported from Germany ...
My latest diagnosis is that right after regeneration, the EGR valve opens (if you are driving it under light load or lift the accelerator pedal - during regen is allways shut) and blows very hot air from after DPF into EGR cooler. There it boils because of insufficient/restricted water flow trough heater matrix which is right after EGR cooler.
I read somewhere that early 2013 models had too thin pipes in heater matrix and it could be easily partially clogged. Later models have updated version of matrix.
I didn't have balls to change the heater matrix yet, though. :)
Last time my car was doing active regen, I heard the start of hissing air trough heater matrix and I imediately put in into S mode - with higher revs it stopped (probably EGR closed) and no coolant came from expansion bottle.
Can anyone back that same symptoms/diagnosis?
 

r90sKirk

Veteran Member
Joined
Oct 21, 2003
Location
CedarTuckey, Michigan
TDI
All TDI's - No gassers! Luxo-Tourer = 13 Passat (hands down, the nicest car we've ever owned), Most fun = MK4 Golf
Have not heard of this issue yet on a MK7, but the symptoms the OP has experienced would lead to a leaking Head Gasket on most of the earlier TDI engines.

The coolant reservoir will get over pressurized from the exhaust gases getting into the coolant passages, and will puke coolant out the reservoir when shut down, and will cause inconsistent heat issues in the cabin - think of "air entraining" in the coolant.
 

Jason11

New member
Joined
Apr 11, 2019
Location
Yorkshire
TDI
Audi A3 Quattro TDI 184
Hello! I am currently having this issue with my 2014 Audi A3....no leaks anywhere else other than over pressurising and coming out of the coolant reservoir.

It sometimes happens every week or 2 but then sometimes it will do it every day for a while, more after harder drives and motorway driving.

I have had the car in at 3 garages, headgasket test done and none can find the issue! I have no other running issues, oil and coolant temps stay normal and the heater works perfectly all of the time.

Anybody solved theirs yet??


Thanks!!
 

Candellara

Member
Joined
Jun 17, 2019
Location
UK
TDI
2013 Golf GT
Hi All,

Have this exact problem (which started as no heat from vents) in my wife's 2013 Golf 7 TDI

I think this maybe all interconnected with the silicant in the expansion tack / heater matrix blocked issue?

Ours started 6 months ago with no heat from vents and a gurgling noise behind the dash area (matrix?). Inlet pipe to matrix was hot and outlet cold. Booked it into VW - they said it's a very common problem and recommended new expansion tank and new matrix (£819). I took the car away as i wasn't convinced

I disconnected heater matrix pipes and flushed with a hose (you can only flush 1 way on this matrix due to the design). Water was flowing freely through the matrix and coolant was clean. Reconnected and topped up the coolant - and nice warm air from the vents. The car was fine for six months until the weekend just gone. Long motorway drive and at idle could hear the gurgling noise from dash area and no heat from the interior vents.

Outside the car, their was water being omitted from the expansion tank. (Note throughout all of this from the start - the car only reads 90 temp and the computer was scanned for fault codes / interior heating flaps checked and all is ok)

So, have changed the reservoir and expansion tank cap, refilled with G13 coolant. I thought about flushing the matrix again just incase the system got contaminated with the silicant bag from the old expansion but both heater pipes are nice and hot, heat from vents and car is bag to normal again

There are dozens of threads regarding this issue all over the forums. Has anyone had a permanent fix and a definitive diagnosis?
 

thundershorts

Top Post Dawg
Joined
Jul 15, 2010
Location
west chester pa
TDI
2015 passat tdi sel premium 2015 golf s tdi gls tdi b5.5, 2002 eurovan,Peugeot 505 td,Citroen cx25 prestige
As long as VW keeps using plastic impellers on their water pumps, the impellers will continue to spin on the shafts. I'd consider it your possible problem.
 

Candellara

Member
Joined
Jun 17, 2019
Location
UK
TDI
2013 Golf GT
As long as VW keeps using plastic impellers on their water pumps, the impellers will continue to spin on the shafts. I'd consider it your possible problem.
Interesting - seems logical but would you not see an increase in coolant temp?
 

Candellara

Member
Joined
Jun 17, 2019
Location
UK
TDI
2013 Golf GT
As long as VW keeps using plastic impellers on their water pumps, the impellers will continue to spin on the shafts. I'd consider it your possible problem.
I think you may be right. It's definitely not the silicant issue.

As stated, 6 months ago (during a motorway drive) we lost heat to the vents and we had gurgling noises from the dash. The car was subsequently booked into VW and their diagnosis was that there are no fault codes present but what is common on MK7 Golfs was that the silica bag in the water expansion tank ruptures and blocks the heater matrix. Price to rectify £819 for new matrix.

I didn't believe them and was a bit miffed that they hadn't tried to flush the system so i took the car away. I disconnected the hoses from the matrix at home and flushed with a hose and water was flowing freely. Upon reconnecting & top up, heat from the vents again!! The car only does local town driving and everything has been well for 6 months UNTIL, a recent motorway drive. Same symptoms, no heat from vents, gurgling noise and some water being forced from expansion tank on this occasion.

After returning home, i ordered a new expansion bottle & cap - very low cost and really to eradicate these items from being any cause. After fitting and checking, we have heat again from the vents.

Well, today i opened up the old expansion tank with a saw - and, the silicant bag is not ruptured and is fully intact with all of it's crystals!!!!! Now this is becoming farcical as the amount of threads there are all over the forums about this exact problem and VW continuing to replace heater matrix's. One poor lady has had 3 heater matrix's as the VW dealer insists that the silicant granules have contaminated the system and continue to block the new heater matrix's. Indeed my local VW dealer wanted to relieve me of £819 for replacing the matrix - when we know the matrix isn't blocked.

Any thoughts?
 

DrSchultze

Member
Joined
Jul 15, 2019
Location
Denmark
TDI
Audi A3 2.0 2013
Been having the exact same problem with my A3 from 2013.
I quickly gave up flushing the heater core, because there is absoutely no space where the hoses enters the firewall, so this weekend I pulled the heater core, and confirmed that it was indeed clogged up with gunk.
I then made a futile attempt at cleaning out the gunk, and then decided to just order a new core, which is in the mail now.


Before coming to the conclusion that the heater core was the problem, I had some test drives, graphing coolant and oil temperature with VCDS, to confirm that thermostat and water pump was working. Moreover the heating as recently disapeared in the driver side, and isn't particular intense in the passenger side.


Also last time it emptied the expansion tank, I could confirm in VCDS that it had just performed DPF regeneration.


Pulling the heater core on my car wasn't that dificult, it's a question of removing the center consle, the cover below the steering wheel and the glovebox, then the core can be pulled out. All in all 1 hour, if you know how to do it. I expect approx the same for assembly.



I would be suprised if it was more complicated on a Golf 7, so£819 sounds like a lot.
 

AdrianC

Member
Joined
Jul 16, 2019
Location
Ireland
TDI
Golf VII GTD
Good evening all..

Glad to know I am not alone with the coolant overflow issue (2014 Golf 7 GTD) 84K Miles.

So just to get you all up to speed;
Just started happening to me over a month ago.
Have had the car a year now with pain free driving and no problems.
Presenting all the symptoms as you guys have already stated.

First time this happened was on long motorway journey, coolant light came on.. Checked Expansion tank and level was below minimum.

Thought nothing of it, topped up and carried on.
No problem.
Checked coolant again once i reached home on the return journey - all normal.

Then on a short run, lost all coolant from the expansion tank.

Booked in my in my local independent garage - said the tank was cracked.
Replaced tank (and not the lid) and I am unsure if the system was correctly bled.

Another long journey and again, Could hearing thumping from behind the firewall. Pulled in, Switched off engine, Got out, popped the bonnet and was met with a little steam so i opened the lid on the expansion bottle to release the pressure and coolant started pouring out the overflow at the bottom of the expansion tank..
Took a video of this as it was happening..
Frustration.

So i went to my local VW Dealer and they have had it 3 week now for testing.
Coolant loss happened once.
They bled the system and after a lengthy pressure test (turned up nothing) and
Conclusion: The Expansion Tank Cap.
Ruled out Head Gasket.
No visible sign of leaks around thermostat or water pump.

I've since purchased sniff tester to detect any combustion gasses seeping into the coolant (should arrive tomorrow).
I will add that there is no mixing of oil/water or water/oil.
Temperature gauge does not rise above 90 Deg C and Oil temp is consistent between 90-100 Degrees C.
No heating issues from the Climatic Control on the dash vents.

It seems all too familiar with you guys who have posted previously.

Still no answer.
 

DrSchultze

Member
Joined
Jul 15, 2019
Location
Denmark
TDI
Audi A3 2.0 2013
Forgot to mention that the car has 112000km on the clock, and first time I noticed the problem was ~6000km ago. In the beginning I didn't have any issues with the heating, they started to really show up ~2000km ago.

I fitted the new heater core yesterday, it took approx 1½ hours, and it turns out that it was unnecessary to remove the glovebox to get the center console out. But on a RHD you'd need to remove it to access the heater core.

Now I just need to wait for a DPF regeneration to happen.

It still test positive for exhaust in the coolant, so mabe the EGR cooler has been damaged by overheating I doubt that the head gasket has failed, as the temperature gauge has never been above 90, and the boilout has only been happening during DPF regen.

So if the new heater core fixes the problem and it doesn't loose coolant, I may just choose to pretend that I never tested for exhaust in the coolant, but I'm eagerly waiting to hear how Adrian's test turns out.

I also did some more troubbleshooting on Google, and found this unlucky fella, who has been in the hands of the stealership: https://www.justanswer.co.uk/volkswagen/a0cr1-2013-diesel-golf-2-0-litre-gt-owned.html

I also find the thermal management section of this article quite interesting: https://www.greencarcongress.com/2014/03/20140322-ea288.html
 

Spipa

Active member
Joined
Jul 18, 2019
Location
Netherlands
TDI
Mk 7 GTD
Hi everyone,

I’ve been following this thread for a while now. My 2013 GTD has exactly the same problems as described. Multiple mechanics have not been able to find a solution for my problems. Learned to accept that I just have to fill it up with coolant once a month. Hope that we’ll find a fix for this.
 

AdrianC

Member
Joined
Jul 16, 2019
Location
Ireland
TDI
Golf VII GTD
Evening all,

Just carried out the sniff test and, as predicted, the result was negative/Invalid.
The liquid should have changed from blue to yellow but took a time to change to green.
This sniff test apparatus has 99.9% accuracy apparently...
So, as a precaution I will test again tomorrow to make sure.

If indeed it was a head gasket then the coolant would boil every time the engine is running and should be overheating..
Also, signs of oil in the coolant or coolant in the oil would clearly indicate a head gasket failure. This is not the case.

I think you may be pointing in the right Direction DrSchultze, I am going to focus now on the EGR Cooler and/or EGR Valve Exhanger for possible hole where air is being drawn for DPF Regeneration..
The Coolant overflow is consistent with DFP Regeneration so I am going to check this out.

I will keep you all updated..

WE CAN GET TO THE BOTTOM OF THIS...
 

DrSchultze

Member
Joined
Jul 15, 2019
Location
Denmark
TDI
Audi A3 2.0 2013
So.. just had a active regen happen this morning, without any drama whatsoever :D No thumbing noises and no loss of coolant, if I hadn't had VCDS running, I would never have noticed. I'll post a graph later showing the temps.


So issue seems so far, to have been fixed with a new heater core, the new core I bought wasn't original, and had substantially larger channels.


So the big question is what will be the next thing go clog up in the cooling system.. Apparently EGR, DSG and Oil cooler, all have tiny channels on the MQB platform.


As for the sniff test, arcording to the manual that went with mine, it states that diesel makes it turn green, and gasoline yellow, in case of a leak.
 

AdrianC

Member
Joined
Jul 16, 2019
Location
Ireland
TDI
Golf VII GTD
Just carried out the test again.

Same Result: A light green colour after a few minutes.

According to the manual the fluid should turn yellow for Petrol, Diesel and LPG..
Green means an Invalid test..
Conflicting statements then say green for diesel = combustion gases present.

DrSchultze: Did you do the same sniff test and what was the result??

It'll now give me an idea where to focus my time and money!!
EGR Valve Excanger and/or heater core..
 
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