Hello everyone,

 

my octavia is 1.8 TSI  and its 3 years old 70k KM.

i want to give some background so maybe you can help me diagnose my problem

 

2 month ago my car water pump have been replaced.

what happen is the in middle of highway my high temp light turn on and when i stopped and checked i sow allot of coolant spill on floor.

when going to the garage they told me water pump fail and needed replacement.

the water pump replaced.

 

 

after month and half i noticed something strange going with my car heater.

when i start the car the coolant temp gauge will get to 90C withing 4-5 min on that time the air flow on the AC is still stone cold when set to highest warmth.

after 10 min the oil temp start getting to 80-85C and only then i will start to feel little warm flow from the AC, only after about 12 min when oil temp is 105C the AC air flow will be warm enough.

 

from what i remember in the past before this started to happen, after 4-5 min when coolant gauge is 90C a very warm air come from the AC.

 

what i checked:

i did air bleeding to system.

i started the engine and check the radiator hose to see if thermostat are stuck open(radiator hose was cold until oil temp reached to 90+ Celsius(no coolnat temp).

i checked both hoses the going to the heater and they both was cold until oil temp reached to 90+C.

 

when the radiator hose becomes hot(probably when thermostat opened) both of the heater hoses become hot gradually.

 

i need some tips on what to check next.

 

you help is appreciated 

 

I am sorry to hear about your troubles. Maybe and only maybe, the silicate bag in the coolant overflow tank has been compromised and the heater matrix is now blocked. There are several topics discussing the issue on this forum. I have just replaced my coolant tank to prevent the issue from occurring, But again, you may have a different problem.

today the mechanic looked on my car he flushed the heater matrix but it was clean.

he bleed the system from air.

he checked for errors but was none.

he check if the main pump  is working, it does working.

he couldnt find the reason for the problem,  he told me he need to check and come back to me.

what he told me is that all the cooling system is working correctly but for some reason the hoses that goes to the heater matrix are not getting hot.

he also check the flaps are working correctly.

i have been told that in the 1.8 TSI version there is a special pump only for the heating system, he think that maybe its failing to work correctly.

 

he told me he want to check with some friends casue its very strange problem.

 

maybe anyone here encounter a similiar problem before?

 

 

Edited 20 February, 20206 yr by Ronaldo131

Im happy to say problem fixed for me.

 

in the end it was the flow valve.

after replacing this part my Heater worked 1-2 min after car started.

 

the flow valve apparently being stuck close and open late when car drive few miles.

 

apparently only 1.8 and 2.0 tsi and tdi engines have this part installed.

 

 

Part number is:
4HC 121 671 D

 

Hope this helps others in the future.

On 23/02/2020 at 20:33, Ronaldo131 said:

Im happy to say problem fixed for me.

 

in the end it was the flow valve.

after replacing this part my Heater worked 1-2 min after car started.

 

the flow valve apparently being stuck close and open late when car drive few miles.

 

apparently only 1.8 and 2.0 tsi and tdi engines have this part installed.

 

 

Part number is:
4HC 121 671 D

 

Hope this helps others in the future.

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Would this part be on a 1,6tdi caycengine)