Coolant air lock

[matt blowen]

Hi there is there a special way to bleed air out of the cooling system? Its a 1.8t agu, heaters blow cold air and i can hear bubbling in the pipes?

 

[aragorn]

I've never had any trouble bleeding a 1.8T, but some folk seem to have a real nightmare with them.

If you glug it full of coolant, start it and drive off, you'll almost certainly have issues, as the engines nowhere near full.

My process is simply dont rush it. Fill it with coolant and leave the cap off. Walk away and leave it for a while. Dont start it, drive it or do anything else. Ususally theres other things that need done on the car so go do those. Check the level periodically and you'll notice its dropped. Refill and leave it again. Repeat a number of times over say an hour or two, giving the big rad pipes a squeeze now and then and that usually does it. The first few times you'll find the tank completely empties itself over a period of time, but with each subsequent fill this will happen less and less, and eventually the level will stay where it is.

When i do the above, once i'm ready to drive i just fit the cap and set off, round the block a couple of times until it comes up to 90 and the stat opens, then recheck the levels, but most of the time they dont move.

 

[Scullies]

I always get air locks. Maybe I'm doing I wrong.

To solve the issue. I fill the header tank till it stops draining, then remove the upper radiator hose fitting and pour some coolant into the radiator.

 

[matt blowen]

Right ive tried everythink, still getting no flow round the matrix? Ive took the small return hose off the top of the header and all that comes out is steam. Any ideas?

 

[matt blowen]

Heaters worked before i drained the coolant

 

[badger5]

manually try and fill the problem pipes as they are the highest ones.
some fill fine, when filled slowly, some are a pig.
have heater on full hot when starting so valves open etc... presuming your valve works and no faultcodes etc??

 

[Andrew@A.L.D]

After my accedent I got one of these

Coolant Filling Kit - YouTube

Not cheap but I won't burn my arm again

 

[matt blowen]

Oh god i remember, how is your arm now? Ive spent all day trying to bleed the car still, ive tried everythink apart from using garden hose because i aint got one

 

[Andrew@A.L.D]

healing well.

 

[dusty]

Hi, you could try getting a 2 litre pop bottle cut the bottom off it then fit a rubber o ring onto the kneck/bottle top end, then use the bottle as a funnel in the coolant resevoir, remove a hose from the engine and overfill with coolant so you have coolant in the funnel, so your coolant in the funnel is well above the position of the engine, this should push any air locks you have out of the disconnected hose, not tried it on the s3 but it used to work on another car that I used to own

 

[matt blowen]

Havent tried this, should i remove the small return hose to vent the air?

 

[dusty]

Yea you will need to remove a hose to allow the air to escape

 

[antwan64og]

I can't recommend it but letting the car cool for 30min and then pulling out the coolant sensor for a few seconds worked for me, there was air in the system that wouldn't budge. Coolant temp wouldn't go above 85.
Sits at 90 now rock solid after my ghetto fix.

Just make sure the pipes are Luke warm not hot!

 

[matt blowen]

Ill try that in a min thanks, im starting to wonder if my water pump is shot

 

[antwan64og]

Undo the coolant cap first. Coolant does pump out of its own accord when you take the sensor outif its warm. I just made sure I did it in the street and not on the driveway, keep her indoors happy...... Then just fill up the coolant reservoir if it goes to low

 

[matt blowen]

Ok so if i let it idle for a bit then turn it off, open cap then pop off the cts and just keep topping up the tank when it gets low?

 

[matt blowen]

Does it help if the car is level?

 

[jay1601]

what temp does the car run at ?

if your not getting any return normally a sign of a failing water pump.

try having it done with a vacuum bleeder.

 

[matt blowen]

Its gets to 90 quicker than before i fixed the water leak, but goes past 90 atfer 15 mins of idle and when it reaches 100 i turn the off

 

[guyzza75]

Hi there ..I had this problem on my a4 2.0 TDI..on mine there was an air lock in my matrix radiator..to cure this I run the car and got warm then find the 2 rubber hoses that go into the car for the matrix..mine are dead centre under bonnet at back to left of battery..anyway undo the clip and pull it back ..then if you look on the rubber hose there is a small like pin hole in it around an inch back on the rubber hose ...gently pull back the rubber hose until the pin hole is clear of the metal pipe and air will hiss out ( I left my engine running).. When the air stops coming out and water squirts through the pin hole your done.. Tighten up the clip again !.. Please do at your own risk and be careful ..1 ..the metal pipes from the matrix radiator are soft aluminium and damage easy when trying to remove rubber hose and are usually very tight 2.. Be careful of hot water ...this worked for me after changing thermostat and temp sensor and still cold blowers p.s the top was the only one I undid and was the tlreturn to engine ..hope this helps everyone ...I have heard stories of head cracked ..water pump gone etc.... All along was an airlock stopping hot air circulating for heating ..