Coolant blown out from expansion bottle

Macrezz

New member
Joined
Aug 20, 2020
Location
Ireland
TDI
2.0l TDI 184
Hello everyone. I am another follower of this thread. Similar story to you all. I am about to start changing the expensive stuff and was hoping some of you might be able to sharpen the direction in which I should start.

My situation.
Car is Seat Leon mk3 2 liter TDI 184
Dual zone climate control.
I changed the bottle cap then the bottle before looking for more information and finding this place.
Little heat out of the vents when the car is hot and the heating is on max. I'm in Ireland. Righthand drive. The far right vent emits the most heat. Tapers off quickly between the other three, running right to left.
Coolant bottle expels it's contents now and then. Probably during dpf regen. I can't say for sure though. If I stop the car and it goes into active regen, I pop the bonnet and release the pressure in the expansion tank. That tends to help coolant loss.
Oil temperature reached 104c this morning on my 25min drive to work. I dove easy but in 3rd gear, keeping the revs around 3k.
Manual says normal temps are 80 to 120c.

After reading here I took my car to get the heating matrix back flushed. My mechanic said he got a strong flow and didn't think there was anything wrong with it.
The other day he contacted Seat. They mentioned the heating matrix and he told them what he thought of the condition of mine. So they told him to change the two circulation pumps. Both costing around €215. They are slightly different pumps.
I don't mind changing both of them but would rather not waste €215 if I don't need to.

Does anyone have any advice?
Is the next step to change both pumps?
Should I change the pump that feeds the heating matrix first and see how it works out?
Or should I be looking elsewhere?

Any help would be greatly appreciated.
Thanks.
 
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nathanso

Well-known member
Joined
Mar 31, 2019
Location
Redwood City, CA
TDI
2015 GSW TDI S 6M
Is there preventative maintenance that might serve to avoid this ugly scenario? Early coolant change? Aftermarket water pump?? I've already swapped out my coolant reservoir so I have the updated, non-perforated silikat pouch but I suspect that's not going to help much if this issue strikes my TDI. I was watching a youtube video on the water pump (
watch at minute 27) and a sticking pump impeller disabler might explain these coolant reservoir blow-out symptoms. I've read VW is dealing with a class action on a different engine's failed water pump so maybe this is similar/common?

EDIT: Just seeing Kamilecki166's post from earlier in this thread reporting the same thing. I'm going to look into swapping out my wp.
 
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Macrezz

New member
Joined
Aug 20, 2020
Location
Ireland
TDI
2.0l TDI 184
Is there preventative maintenance that might serve to avoid this ugly scenario? Early coolant change? Aftermarket water pump?? I've already swapped out my coolant reservoir so I have the updated, non-perforated silikat pouch but I suspect that's not going to help much if this issue strikes my TDI. I was watching a youtube video on the water pump (
watch at minute 27) and a sticking pump impeller disabler might explain these coolant reservoir blow-out symptoms. I've read VW is dealing with a class action on a different engine's failed water pump so maybe this is similar/common?

EDIT: Just seeing Kamilecki166's post from earlier in this thread reporting the same thing. I'm going to look into swapping out my wp.
Hi. Just wondering what your situation is? Car/Engine, mileage & symptoms?

I was just onto Seat in the hope for a little more information about which direction to go but nothing unfortunately. Could be the matrix, either two circulation pumps & now you highlighted the water pump.

Edit.
Checked my milage. I'm at 117,000km. Timing belt change is 210,000 or five years, car is 2013 so I'm due a change. At least that is a constructive thing to try, so I'm going to sort that with the water pump, then see where I am.
 
Last edited:

shocks

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)
Hi. Just wondering what your situation is? Car/Engine, mileage & symptoms?

I was just onto Seat in the hope for a little more information about which direction to go but nothing unfortunately. Could be the matrix, either two circulation pumps & now you highlighted the water pump.

Edit.
Checked my milage. I'm at 117,000km. Timing belt change is 210,000 or five years, car is 2013 so I'm due a change. At least that is a constructive thing to try, so I'm going to sort that with the water pump, then see where I am.
Macrezz, I wouldn't go too far down the rabbit hole on the water pump being the issue. I was losing coolant from my bottle and I had exhaust gases in my coolant so I concluded the two were connected. I thought my water pump was the smoking gun ... but after replacing this and the head gasket I lost coolant on my very first drive to work. Like so many other people here with this issue, it was simply a case of a small amount of buildup in the heater matrix coupled with the heat from the EGR valve reopening after DPF regen (and a clear design flaw in VW's cooling system). I replaced my heater matrix and I haven't lost a drop of coolant after 14,000 kms.

The pump did possibly cause the other issue of exhaust gas in my coolant as I can't detect it anymore after changing the head gasket and pump, who knows though. Heater Matrix should be the first and one of the cheapest repairs you try in my opinion. You can even do it your self, it's particularly easy on a RHD vehicle.
 

nathanso

Well-known member
Joined
Mar 31, 2019
Location
Redwood City, CA
TDI
2015 GSW TDI S 6M
My solution for preemptively avoiding the jammed water pump impeller shroud issue and the resulting damage a sealed-system overheat could cause was to disconnect the water pump solenoid and connect the wiring harness to a new, second solenoid that I purchased for this purpose. Thus far, over a half-dozen trips and several hundred miles, my ECT has remained in the 192-197F range (according to my ODB2 scanner) and no error codes have been thrown.

 

Macrezz

New member
Joined
Aug 20, 2020
Location
Ireland
TDI
2.0l TDI 184
Macrezz, I wouldn't go too far down the rabbit hole on the water pump being the issue. I was losing coolant from my bottle and I had exhaust gases in my coolant so I concluded the two were connected. I thought my water pump was the smoking gun ... but after replacing this and the head gasket I lost coolant on my very first drive to work. Like so many other people here with this issue, it was simply a case of a small amount of buildup in the heater matrix coupled with the heat from the EGR valve reopening after DPF regen (and a clear design flaw in VW's cooling system). I replaced my heater matrix and I haven't lost a drop of coolant after 14,000 kms.

The pump did possibly cause the other issue of exhaust gas in my coolant as I can't detect it anymore after changing the head gasket and pump, who knows though. Heater Matrix should be the first and one of the cheapest repairs you try in my opinion. You can even do it your self, it's particularly easy on a RHD vehicle.
Thanks for your reply.
Maybe you are right. I'm caught between what to change next. Seat have suggested I go in for a diagnostic test to find out what's wrong. I asked them twice if the test would tell me if there is a problem with circulation pumps or the matrix. They evaded the question both times. I feel like the test will be a waste of €90.
I was all set to change the matrix at the start of the year. That changed when my mechanic said he got a good flow through it. I haven't been able to make a decision since.
I wouldn't have a clue of how to change the matrix myself. Is there a video guide by any chance? I'll pawn it off to an expert if it looks to much for me.
Thanks again.
 

shocks

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)
I wouldn't have a clue of how to change the matrix myself. Is there a video guide by any chance? I'll pawn it off to an expert if it looks to much for me.
Thanks again.
looks like someone made a video here ...

If you have no experience working on engines then maybe avoid this one, I would describe it as a little bit harder than an oil change and you'll need an air compressor to blow the matrix clear of coolant before disconnecting all the coolant pipes or you'll have a mess in your cabin. The procedure in the service manual covers everything in detail, you can get these manuals from the Erwin Volkswagen website for a fee (it's time based but you can just buy 1 hour and download all the manuals at once for your car).

I wouldn't pay the 90 euro for the test, the whole job is probably a 300-400 euro job including parts and labour. Less than 200 if you do it yourself.
 

Macrezz

New member
Joined
Aug 20, 2020
Location
Ireland
TDI
2.0l TDI 184
Th
looks like someone made a video here ...

If you have no experience working on engines then maybe avoid this one, I would describe it as a little bit harder than an oil change and you'll need an air compressor to blow the matrix clear of coolant before disconnecting all the coolant pipes or you'll have a mess in your cabin. The procedure in the service manual covers everything in detail, you can get these manuals from the Erwin Volkswagen website for a fee (it's time based but you can just buy 1 hour and download all the manuals at once for your car).

I wouldn't pay the 90 euro for the test, the whole job is probably a 300-400 euro job including parts and labour. Less than 200 if you do it yourself.
Thanks again.
Really appreciate it.
 

Gavk

New member
Joined
Oct 18, 2020
Location
Irepand
TDI
2.0 tdi fr
Hi all, I have a 14 leon fr 184 BHP. I have just replaced my heater matrix 2 weeks ago as I was having the same symptoms as a lot on here, coolant blowout from cap, no heat coming through the vents pressure tested and gas tested all was good.Since I replaced the heater the heat has came back, great. But I checked the coolant there today for the first time since I got the heater replaced and the coolant was just in the middle between max and min, when it was replaced it was at max,
My question is should the coolant have to be topped up again? I have drove the car about 200 miles since I got it back and stopped it up once with about 200ml coolant
 

MaximisDoom

New member
Joined
Oct 18, 2020
Location
Nottingham UK
TDI
2.0 184
I had the same issue with a coolant blow out and then a subsequent loss heat in the cabin. The heater gets fairly warm but not hot when blower on low and driving round town but on a long run, speeds over 40 - 70 mph the heater goes cold. Or if the blower is turn up to half way or above the heater goes cold. I have replaced the main water pump with cam belt change and also replace the secondary pump due to a warning light saying the secondary pump was not functioning and I still have exactly the same problem. Only thing left to do is try the heater matrix. Are there any coolant flow control solenoids etc on the heater matrix part of the circuit as SEAT are totally unhelpful as usual? I will post back if I ever manage to get this sorted!
 

MaximisDoom

New member
Joined
Oct 18, 2020
Location
Nottingham UK
TDI
2.0 184
Hi all, I have a 14 leon fr 184 BHP. I have just replaced my heater matrix 2 weeks ago as I was having the same symptoms as a lot on here, coolant blowout from cap, no heat coming through the vents pressure tested and gas tested all was good.Since I replaced the heater the heat has came back, great. But I checked the coolant there today for the first time since I got the heater replaced and the coolant was just in the middle between max and min, when it was replaced it was at max,
My question is should the coolant have to be topped up again? I have drove the car about 200 miles since I got it back and stopped it up once with about 200ml coolant
I'd say that amount of water displacement is totally normal as some air could have circulated through the system, hence the water in the bottle replacing said air. I'd give it a good run and check again as when I had both pumps changed it took a couple of top ups in mine before the level stayed consistantly at the same level.
 

Gavk

New member
Joined
Oct 18, 2020
Location
Irepand
TDI
2.0 tdi fr
I'd say that amount of water displacement is totally normal as some air could have circulated through the system, hence the water in the bottle replacing said air. I'd give it a good run and check again as when I had both pumps changed it took a couple of top ups in mine before the level stayed consistantly at the same level.
Thanks for the info maximisdoom I was thinking the same about the air.hopefully it will sort it self out and find its level, dont want replacing more parts. Car is running fine since the new matrix no blow out when regen or on long drive, where as before after a regen or long drive the coolant would be empty
 

Dandan62

New member
Joined
Nov 10, 2020
Location
Sussex
TDI
Seat lein
Just to add to this common issue I had the same symptoms of losing coolant through the expansion tank. The silicone balls had gone from the tank and I had no hot air. It took 3 system flushes, replacement matrix and new coolant tank but all is fine now. I luckily have a model where with practice the matrix can be removed in 20 minutes! I will be doing a yearly flush and keeping an eye on the silicone balls from now on!
 

Wiseman22

New member
Joined
Nov 28, 2020
Location
Bucharest
TDI
Golf mk7 variant 2.0 TDI 150HP
Hej guys, I am new here and can share my same experience with a Golf mk7 variant 2.0 tdi 150 hp, 120,000 km.
March 2020 - loosing coolant heavily and heating wasnt working at all and had smell of exhaust gasses in the coolant tank. Service said there is some kind of residue in the coolant (they blame the coolant but i use G7 original wv only). Water pump was blocked so i replaced it and for heating they washed the matrix and started working again (didnt work as it shouls but i would only figure it out way later) .
Sep 2020 - 4000 km after, didnt use heating all summer. Heating disnt work well when i tried. Started loosing more and more coolant again, it never stooped completley actually. Service found pump blocked again and said i am loosing coolant through the gas cooler + EGR unit which gives the bad smell in the coolant tank because it looses gases in system.After changing EGR and pump again, they washed again the heater but the heat was not working as it should. So then they said that the matrix heater was still clogged even after washing for 2 days with the special liquid.
After i changed the matrix, my heating is burning my hand and disnt loose coolant for 1000 km even reved up.
Dont be scared if after changing matrix you lose some coolant, the system is clearing the air inside and you have to fill in when engine is cold (in my case i added up to 500ml) but not a drop since last refil.

I am sure the matrix was clogged and that solved it but i am not 100% about the EGR loosing coolant and giving the smell. I didnt fimd anybody who can test the bad part yet.

As previously mentioned i also recommend you start with the cheapest - matrix heater and after that see if you still have issues.
 

dtrvler

Veteran Member
Joined
Jul 21, 2017
Location
Las Vegas
TDI
2006 Jetta TDI 5 spd
Boiling coolant out of the overflow means bad oring on coolant bottle or other lack of seal in cooling system. It needs to be under pressure. Pressure test cooling system.
Bubbles in the cooling system is often misdiagnosed as combustion pressure leaking into cooling system.
 
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