bleed screw/hole ?

[Andyalex]

Hi All

I have a 2016 A6 C7 2ltr diesel ..been great car 190,000 miles an still running lovely (except) .

I had the expansion tank off, i now seem to have air in the system.

after i had the tank off, i refilled system, with heater on
full and fans on,

till i thought i had got all the air out of the system, but it seem i havent.

alll the vents put out hot air, only the drivers side on the front seems to only put out luke warm air, then will go cold after a few miles driving, but then will go luke warm again.

i have searched for the last few weeks online to see if there is a bleed screw or hole, so i can make sure i have got all the air out of the system.

last night went for a drive, again luke warm air from drivers side vent, after around 5 miles, the air went cold from the vent,

stopped and checked top rad hose, it was cold..got home and top rad hose was warm,and ddriver vent was putting out luke warm air..

any help accepted .

Thanks in advance

Andy

[Crasher]

It should self bleed when taken up to fan running temperature and left too cool to ambient.

[aw911]

If it is like the 3.0tdi heater matrix.....there is a bleed hole located on the left hand heater matrix hose which lives under the plastic scuttle cover panel for the windscreen wipers. You need to undo the hose clip and then slide the rubber pipe down until the bleed hole becomes exposed....you will then be able to bleed the air out the system until coolant starts spraying out in a constant stream and then refit the hose.
I have just renewed the heater matrix on mine because it was constantly blowing cold on the drivers side and despite blowing the matrix through with compressed air and then flushing it through with water and then refilling and bleeding the system it made no difference. Since renewing the heater matrix it now blows lovely toasty warm air from all the vents. Your problem only seems to have arisen since you have messed around with the expansion tank....so your issue is probably air in the system thank goodness. On the 3.0tdi engine there is also a bleed screw near the EGR cooler I think....but I cannot comment on the 2.0 diesel. Hopefully that info may help.

https://youtu.be/hc7uoln2u5s

The YouTube link above from the point 18 mins to 20 mins into the video shows the heater matrix pipes....you can see the bleed hole in the left hand hose and what he does to get it to bleed.....please be careful when using pliers on those bulkhead pipes....you do not want to fracture those pipes! He is just rotatating the rubber to break the stiction due to them very rarely (if ever) being removed.