The heater has always been a bit cool. We replaced the double thermostat but it made no difference. Next plan is to replace the heater matrix in case it is blocked. Just been reading up about the cooling system on these engines - pretty complicated aren't they. I'm wondering what part the electric coolant pump plays. Does it circulate water through the heater before the mechanical pump starts working? If the electric pump was faulty could this be the cause of a tepid heater? If it was faulty would it show an error code?
1.2tsi tepid heater
- Thread starter dwlawson
- Start date
Not every coolant circulation "disorder" will prompt a FAIL flag, I think that the electric pump only works on the charge cooler circuit.
Have you got an IR thermometer, is so why not use it on the pipework and see you find anything unusual or not what you would expect, even feel the pipes IN and OUT of the heater matrix and main radiator.
Edit:- ideally you need to work out if the heater matrix is receiving hot water and returning slightly cooler water - or is the temperature flap motor unit faulty and so not directing enough of the incoming air through the heater matrix.
Have you got an IR thermometer, is so why not use it on the pipework and see you find anything unusual or not what you would expect, even feel the pipes IN and OUT of the heater matrix and main radiator.
Edit:- ideally you need to work out if the heater matrix is receiving hot water and returning slightly cooler water - or is the temperature flap motor unit faulty and so not directing enough of the incoming air through the heater matrix.
What year is your car, ie the engine the 16V version with a belt driven cam shaft?
The 16V 1.2TSI does have a reasonably complicated cooling system, ie probably in 3 sections.
What colour was the coolant when you drained it?
I bought a Draper Coolant Vacuum Refill Kit to help refill the cooling system on my 2011 S4, that worked very well.
When I get round to changing the coolant in my wife's August 2015 VW Polo 1.2TSI 110PS from G13 to G12eco, I'll be using that kit again, there will be a routine in VCDS to allow you to operate the electric coolant pump to further help to purge any air out - that option was not available in VCDS for my 2011 S4!
Edit:- this seems to be becoming an issue at least for the earlier 1.2TSI 8V engine, I always thought casting sand left in the cast parts of the engine was only a TDI engine problem. Does the coolant reservoir have a Silicate pouch in it?
The 16V 1.2TSI does have a reasonably complicated cooling system, ie probably in 3 sections.
What colour was the coolant when you drained it?
I bought a Draper Coolant Vacuum Refill Kit to help refill the cooling system on my 2011 S4, that worked very well.
When I get round to changing the coolant in my wife's August 2015 VW Polo 1.2TSI 110PS from G13 to G12eco, I'll be using that kit again, there will be a routine in VCDS to allow you to operate the electric coolant pump to further help to purge any air out - that option was not available in VCDS for my 2011 S4!
Edit:- this seems to be becoming an issue at least for the earlier 1.2TSI 8V engine, I always thought casting sand left in the cast parts of the engine was only a TDI engine problem. Does the coolant reservoir have a Silicate pouch in it?
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It's a 62 reg with a chain. The coolant was still pinky purple as it was fresh when the thermostats were replaced last year. The gunge in the heater matrix was light brown, perhaps that is where the casting sand explanation came from. Not sure I buy that idea - if it is in the waterways it would also be in the oil ways and the engine would grind to an early death. No pouch in the reservoir but there were some pink crystals at the base of the tank. Perhaps it split and the previous owner removed it. Anyway, job done and a nice toasty cabin.
Good end result!
I'd think that your car is too early to have a Silicate pouch fitted into the reservoir it would have left the factory with G13 in it, and I think at least originally G13 only needed these Silicate pouches on certain engines where extremes of coolant temperature would occur.
My wife's August 2015 VW Polo 1.2TSI 110PS would also have left the factory filled with G13, and I plan to remove that and replace it with G12eco within the next year or two, and the reason that I'll be happy to make that change is down to my lack of confidence in G13 - though VW Group are keeping very quiet about it having issues - though why did these Silicate pouches suddenly start appearing round about 2016-2017.
It could just be that any "iron" drop out is occurring in the heater matrix, and some people who have examined them have commented that the size/gauge/diameter of the individual tubes in these heater matrix are exceedingly small, maybe smaller than what they were in earlier VW Group cars in a bid to reduce cooling system capacity and so influence the heating up time to minimise exhaust emissions, if so I'd think that all VW Group cars of that age and newer will be prone to heater matrix chocking up in service.
When I replaced the G12++ with G12eco in my 2011 Audi S4, I noticed that there was some "iron" drop out in the bottom of the main radiator - maybe that car model being older would have larger tubes in its heater box - who knows.
I've run a 2000 VW Passat 4Motion for 13 years/85K miles, and a 2002 VW Polo 1.4 16V 75PS for 13 years 105K miles without any issues with chocking heater matrix though both of these cars had timing belt and so coolant changes at least twice in their life with us.
I'd think that your car is too early to have a Silicate pouch fitted into the reservoir it would have left the factory with G13 in it, and I think at least originally G13 only needed these Silicate pouches on certain engines where extremes of coolant temperature would occur.
My wife's August 2015 VW Polo 1.2TSI 110PS would also have left the factory filled with G13, and I plan to remove that and replace it with G12eco within the next year or two, and the reason that I'll be happy to make that change is down to my lack of confidence in G13 - though VW Group are keeping very quiet about it having issues - though why did these Silicate pouches suddenly start appearing round about 2016-2017.
It could just be that any "iron" drop out is occurring in the heater matrix, and some people who have examined them have commented that the size/gauge/diameter of the individual tubes in these heater matrix are exceedingly small, maybe smaller than what they were in earlier VW Group cars in a bid to reduce cooling system capacity and so influence the heating up time to minimise exhaust emissions, if so I'd think that all VW Group cars of that age and newer will be prone to heater matrix chocking up in service.
When I replaced the G12++ with G12eco in my 2011 Audi S4, I noticed that there was some "iron" drop out in the bottom of the main radiator - maybe that car model being older would have larger tubes in its heater box - who knows.
I've run a 2000 VW Passat 4Motion for 13 years/85K miles, and a 2002 VW Polo 1.4 16V 75PS for 13 years 105K miles without any issues with chocking heater matrix though both of these cars had timing belt and so coolant changes at least twice in their life with us.
My Audi A3 had a silica bag and it was a 63 plate
This split and that was the death of the heater matrix
Easily identifiable by the words MIT SILIKAT on the coolant reservoir tank
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