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Since changing out all the transaxle fluids this year, I decided I want to make it a clean slate and also change out the brake fluid and the coolant. I've done the brake bleed myself a few years ago when I changed pads and rotors, but I have not attempted a coolant flush. I have been unable to find a tutorial for flushing the coolant on the 2.0T. Has anyone come across a good tutorial or video on the process? If so, can you post it here? Thanks.
Open the expansion tank cap and drain coolant via lower rad hose drain valve by turning 90 degrees with a small crescent wrench. IIRC the valve only turns one way and can become a bit brittle with age so don’t break it 😉
Can attach a rubber hose extension to the outlet for less splashing in the drain pan if needed.
If you don’t want to mess around bleeding and burping cooling systems and risk air traps then I highly recommend acquiring an Airlift system. I have used this one a lot and has worked perfectly every time and very rare do I have to top up coolant after fill and test drive.
Warm climates can mix pure coolant with distilled water 50:50 but I highly recommend cold climates to use 60:40 as this will lower the freeze point to -40C. Do not increase coolant ratio above 60% as more is not better. Too high coolant ratio can cause the coolant in the system to gel in extreme cold ambient temps. Use the Audi coolant spec that matches the owners manual and the stamp on the expansion tank. Avoid using “generic” coolants that say they are compatible with all vehicles for best long term results.
Last edited by AudiAllTheWay; Oct 11, 2024 at 08:50 AM.
Thanks for the tips! I will definitely take a look at that tool. Is there any other benefit besides preventing trapped air? Does it speed up the process, like requiring less time running the engine to flush out the old coolant? I was planning on just getting one of those big funnels to "burp" out trapped air while running the engine and opening up the heater core.
Oh, and is it really critical to have an air dryer system on the air supply? I just have a small but relatively new air compressor.
I have never run an Audi engine to flush out old coolant as I have only used gravity drain. Another trick to get more old coolant drained is to use a rubber glove to mostly make a seal around the expansion tank opening while blowing compressed air into the cooling system. Obviously reason applies here meaning do not pressurize the system to shop air 120+PSI pressures but rather use some low air pressure to repeat pulse push more old coolant out the open drain valve. If you really want to go all out then pull the engine block drain plug (if available) and consider to disconnect the heater core and push coolant out of it as well.
The Airlift system uses shop air to create a vacuum in the cooling system so no real need for an air dryer. I do use a water trap on shop air which is good practise for max life of air tools.
I have never run an Audi engine to flush out old coolant as I have only used gravity drain. Another trick to get more old coolant drained is to use a rubber glove to mostly make a seal around the expansion tank opening while blowing compressed air into the cooling system. Obviously reason applies here meaning do not pressurize the system to shop air 120+PSI pressures but rather use some low air pressure to repeat pulse push more old coolant out the open drain valve. If you really want to go all out then pull the engine block drain plug (if available) and consider to disconnect the heater core and push coolant out of it as well.
The Airlift system uses shop air to create a vacuum in the cooling system so no real need for an air dryer. I do use a water trap on shop air which is good practise for max life of air tools.
Is the Airlift system intended only for the refill step or can it also be used to run a flush with distilled water prior to refilling? I'm just thinking that a gravity drain and then refill using the tool would not get all the old coolant out of the system. I would want to do a flushing step and a second drain in between, whether just manually (running engine for a short period) or using the tool and not running the engine.
The Airlift instructions indicate it is for creating a vacuum in the already empty coolant system in order to fill the system while avoiding air traps.
I am not sure how you are going to maintain a known new coolant to fresh distilled water ratio mix when running the engine while draining and filling at the same time. You will need several times the amount of premixed coolant that the system holds to do the full flush the way you are describing. Anything is possible but the downside is this approach would waste a lot of new coolant!
The Airlift instructions indicate it is for creating a vacuum in the already empty coolant system in order to fill the system while avoiding air traps.
I am not sure how you are going to maintain a known new coolant to fresh distilled water ratio mix when running the engine while draining and filling at the same time. You will need several times the amount of premixed coolant that the system holds to do the full flush the way you are describing. Anything is possible but the downside is this approach would waste a lot of new coolant!
Yeah, that was one of my concerns. Thoroughly flushing and refilling the coolant is not as simple as it would seem. If flushing with distilled water, there will always be some distilled water that remains in the system if just draining by gravity at that one point on the lower radiator hose. I believe the dealerships have power flushing equipment that solves this problem, but I saw some estimates of $400+ to have the flush/refill done by an Audi shop.
Don't make it too complicated, simply use the concentrated coolant and lots of distilled water.
Open the lower coolant pipe to empty the old coolant then fill with distilled water, running 20-30 minutes depends on the weather. let coolant circulate
I normally do it 3-4 times, of course turn the heater to high. when it's clear water then fill 4.5L CONCENTRATED coolant, it's about 50:50.
Don't make it too complicated, simply use the concentrated coolant and lots of distilled water.
Open the lower coolant pipe to empty the old coolant then fill with distilled water, running 20-30 minutes depends on the weather. let coolant circulate
I normally do it 3-4 times, of course turn the heater to high. when it's clear water then fill 4.5L CONCENTRATED coolant, it's about 50:50.
maybe it need to top up later.
I would definitely want to be sure I get at least 50% antifreeze in the mix because I live in a Northern climate (WI). Your tip on the 4.5L concentrate turned on the light bulb. As long as I know the total coolant capacity for the 2.0T, flushing with plain distilled water should not be a concern because I will know to fill at least 50% of the capacity with concentrate and then top off with distilled water. I can't imagine that a gravity drain will not remove at least 50% of the coolant from the system.
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Coolant Flush and Fill (2.0T)
