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VW MK7 GOLF Cooling issues

EdwardJones

New member
Location
Uk
Car(s)
VW GOLF MK7 1.6 TDI
Hi all, I have a 2015 VW Golf MK7 1.5 TDI - 65,000 miles.

I am having issues with the in car cabin heating system. The engine runs at a perfect temperate so the issue seems to be linked to the heater matrics under the dashbord. I know it is a common problem with it getting blocked however I have flushed the coolant system through twice now and it was running clean.
Initially after refilling the coolant, the cabin air is hot, as it should be, however after about 5/10 minutes driving it seems to stop being hot and just slowly cools down until it’s like warm at best. It’s as of water isn’t flowing though the heater matrics (although it is at the start of my journey)? Perhaps linked to car coolant thermostat? Air getting in system?
Any help would be appreciated!

Kind regards,
Ed
 

YamR1rider

Drag Racing Champion
Location
Tampa, FL
Car(s)
2017 GTI Sport DSG
I'm currently having a similar problem (no/little heat) with my daughter's 2015 Tsi. I have replaced the heater core, which only partially fixed the problem. Next up, once the part arrives next week, I will be replacing the N82 solenoid/check valve further up the system line which I suspect is probably failed closed.
 

EdwardJones

New member
Location
Uk
Car(s)
VW GOLF MK7 1.6 TDI
Interesting. The heater matrics behind the dash gets too hot to touch (both the bottom and top pipe), when the air is set to cold. However as soon as I turn it to hot, I get hot air for a moment, and then once it has blown through the hot water already in the rad, it goes cold again. So water seems to flow when set to cold however not when it’s set to hot.

I am not sure if it has air in the system which just won’t budge. I have tried pumping all the pipes possible. I flushed the whole system and if it was empty when I started refilling it, it’s probably got 4/5 litres in max.

There is also a large pipe at the bottom of the radiator running across the front of the car. It has some water in but isn’t full. Should it be? The fan seems to take along Time to kick in so I wonder if the radiator has air in. Any tips to get it out….?
All seems very strange!
 

YamR1rider

Drag Racing Champion
Location
Tampa, FL
Car(s)
2017 GTI Sport DSG
That is very weird.....could it be your matrix is blocked and water not flowing through? With my daughter's car, only one of the pipes to the matrix is hot (which is why I think the N82 checkvalve in the other line is failed closed). I get lukewarm air after quite some time but its not as it should be (my own GTI for instance warms up very quick).

As far as getting air out of the coolant system, I've got a cheap vacuum fill tool (tool) which really helps - but you do need an air compressor as well (nothing high powered or fancy).

Are you sure that large pipe doesn't have much water in it....it is a fairly squishy pipe that one for want of a better word but I dare say its probably fuller than you realize. I think air pockets are more likely to form at higher or offshoot points in the system rather than the big bulk pipes. If that large hose wasn't functioning right you'd probably have engine overheating issues.

On these cars though, after a while the air pockets do seem to come up to the coolant tank in the end (as its the highest part of the system). If the level is correct in the tank after a few short drive rounds (with your heater on full blast) and squeezing/burping the hoses, the coolant level its generally right.
 

Damask_Rose

New member
Location
United Kingdom
Car(s)
Golf mk7 1.4 tsi
That is very weird.....could it be your matrix is blocked and water not flowing through? With my daughter's car, only one of the pipes to the matrix is hot (which is why I think the N82 checkvalve in the other line is failed closed). I get lukewarm air after quite some time but its not as it should be (my own GTI for instance warms up very quick).

As far as getting air out of the coolant system, I've got a cheap vacuum fill tool (tool) which really helps - but you do need an air compressor as well (nothing high powered or fancy).

Are you sure that large pipe doesn't have much water in it....it is a fairly squishy pipe that one for want of a better word but I dare say its probably fuller than you realize. I think air pockets are more likely to form at higher or offshoot points in the system rather than the big bulk pipes. If that large hose wasn't functioning right you'd probably have engine overheating issues.

On these cars though, after a while the air pockets do seem to come up to the coolant tank in the end (as its the highest part of the system). If the level is correct in the tank after a few short drive rounds (with your heater on full blast) and squeezing/burping the hoses, the coolant level its generally right.
Did you replace the N82 coolant shut-off valve in your daughter's Golf? If so, did it solve the problem?
 
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