Several typical coolant leaks originate from the coolant flange, which is situated at the rear of the Audi 1.8T cylinder head. With two threaded studs, it fastens to the head and is made of plastic. The studs support two tubing brackets, including a stand-off bracket for the turbo oil line, in addition to holding the coolant flange in place.
- The flange houses the Coolant Temperature Sensor and provides coolant to two coolant hoses. The Coolant Temperature Sensor is secured with an o-ring and a u-shaped plastic lock clip.
- An integrated sealing ring is part of the lower coolant hose. A metal spring clip that fits matching grooves in the hose neck and flange holds the hose in place as it glides onto the lower flange neck and snaps into position.
- Here is a right angle picture of the same coolant flange, highlighting the two head stud mounting holes. Take note of the hose with an elbow to the right. The flange is joined to a steel coolant tube via this hose.
- Spend more time cleaning the mating area where the flange mounts at the back of the cylinder head. To effectively seal, the flange o-ring needs a smooth, clean surface.
The installation and removal of spring-style hose clamps is a simple using a spring clamp tool. To expand the clamp, attach the tool and squeeze the handle until it locks in place. The clamp may now be removed and put back on with the use of both hands.
For effective freeze/boil-over protection and chemical protection against rust, corrosion, and toxic deposits, a proper blend of pure coolant and distilled water is crucial. The most precise instrument for calculating mix ratios is a refractometer.
Even though you can fill the cooling system without specific gear, we recommend using a vacuum refill tool. Simply connect the tool to shop air and fit the rubber cone of the tool into the neck of the coolant jug. Turn the valve to create a vacuum in the system, then turn it to “fill” and allow the vacuum to draw in new, pre-mixed coolant from a container.
In This Article...
Kit Contents
Your Coolant Flange Kit with Coolant (ES2602886) comes with two quarts of pure coolant in addition to a new coolant flange with an o-ring, attachment studs, an engine Coolant Temperature Sensor with an o-ring, and a plastic retainer clip.
We have recommended them for a leak-free repair and have highlighted related, optional goods that are sold separately. These include a bottle of cooling system flush and the two hoses that are fastened to the flange. Expect to find one or both of the hoses worn out if you are changing a coolant flange to fix a leak.
Be ready, especially if the system has been ignored, as you can discover an unpleasant buildup of muck and rust in the system, as we did.
Note: Depending on whether you’ve taken your car apart before, you might need to buy a few different-sized worm-style hose clamps to finish the task.
Under the carStep 1
- Remove the pressure cap on the expansion tank.
- Lift the vehicle, then take off the belly pan.
- Take the coolant out.
- Turn the bleeder counterclockwise until the coolant is flowing freely at the base of the lower radiator pipe (arrow). (see slide no. 2)
Under the CarStep 2
If the drain plug is stuck, you might need to use pliers to turn it. You can pull the clip on the temperature sensor (arrow) and take it out if it is truly stuck and feels like it might break so you can empty the coolant. If you choose to go this route, swap out the sensor’s o-ring.
As you open the drain-cock, fasten a length of flexible plastic tubing to the drain output nipple to prevent coolant from leaking everywhere. This will, as we are doing here, route the coolant flow to a catch container.
Under the HoodStep 6
- At either end of the crankcase vent tube, loosen the hose clamps.
- The hex head bolts securing the tube to the valve cover should be removed with a 5mm driver.
- The valve should be removed by unplugging it from the hoses at each end.
Under the HoodStep 11
The hose at the combi-valve and the hose on the purge line adjacent to it should both be free of clamps (arrows). Our car already has worm clamps installed, but yours might come with factory crimp-style clamps that need to be removed and changed.
Under the HoodStep 15
Keep in mind where the combi-valve bolts and thin stamped metal gasket are located. As you remove (or reinstall) the valve, take careful not to drop the gasket behind the engine as it will fall off easily.
Under the HoodStep 16
The flange at the back of the cylinder head is visible now that the combi-valve is out of the way. There are several coolant leaks, and coolant crust has covered everything.
As you can see, there are barely a few inches between the firewall and engine back here.
Under the HoodStep 17
With a pick or screwdriver, remove the plastic retention clip that is holding the Coolant Temperature Sensor electrical connector in place. Then, pull the sensor out of the flange, wiring and all.
Under the HoodStep 18
It is simpler to unplug if the sensor is pulled up. To detach the black electrical connector from the sensor, pull while simultaneously applying pressure to the release tab.
WARNING: Look for corrosion on the electrical contacts inside the connector. If required, clean the contacts using a spray cleaner. This sensor has a high importance, hence the connection must be reliable.
Under the HoodStep 19
Reach down and pull the metal clip out of the plastic collar of the lower hose until it hits the stops if you plan to reuse it. To remove the hose from the flange, wiggle it.
NOTE: The top and bottom tubing support brackets are held in place by retaining nuts. Even with both nuts removed, the flange will not move. The studs must be taken out individually.
Under the HoodStep 20
The retainer nut on the flange stud is visible in the bank shot photo below, which was taken using a mirror. The turbo oil tube is supported by the lower bracket in this image.
A purging line bracket is held in place by another, comparable nut that is located on the top flange stud.
Under the HoodStep 21
The two retainer bolts holding the oil tube to the side of the engine must be taken out before we can snap the bracket for the oil tube off the lower flange stud. With a 6mm hex driver and ratchet, remove them both (arrow).
When the tube is unblocked, you can move it far enough backward to release the support bracket from the bottom flange stud.
Under the HoodStep 23
The old hose is worn out, and a thumb-and-forefinger squeeze reveals that it is squishy at the swelled location marked by our arrows.
Note: In this instance, the factory crimp clamp will likely need to be replaced with a new worm clamp after being cut off (right arrow).
Under the HoodStep 24
The flange can now be unbolted and removed. We remove the flange by unscrewing both threaded studs with a 10mm wrench.
Because our bottom hose was leaking so severely, we simply cut the rubber and removed it, leaving the coupler attached to the flange.
Ugh. We can tell from a quick glance inside the flange that this system has to be cleaned to get rid of these substantial deposits.
Under the HoodStep 26
The bottom hose will be pre-installed on the flange. Pushing the new hose coupler onto the flange until the coupler clip snaps in place is much simpler when working on a bench.
This connection needs to be made after the engine’s flange is mounted if you’re utilizing the old hose.
Under the HoodStep 27
The Coolant Temperature Sensor should now have the replacement o-ring attached. Once the plastic retainer clip can be fully inserted as shown, put the sensor into the flange.
Under the HoodStep 28
Put the assembly in place. Both nutted-studs should be manually threaded into the head through the flange holes. Alternate between tightening the two to uniformly clamp the flange.
Both brackets should be reinstalled over the nutted-studs and fastened with the 6mm nuts.
If you need a refresher on component placements, see the illustration on page 2.
Flushing
Use distilled water, which is accessible at most grocery stores, to combine your fresh coolant. For best results, aim for a final antifreeze/water ratio of 50/50.
By using distilled water, you can avoid issues brought on by hard scale that forms when minerals in tap or well water settle out and regenerate. Filling On page 4, we mentioned the vacuum fill tool. Watch how it draws a vacuum inside the cooling system, sucking the hoses flat.
This method of system filling saves the inconvenience of “The system should be burped to release any trapped air.
bleeding and filling A vacuum fill tool is absent. Then you’ll have to proceed using more traditional methods.
Through the overflow bottle, refuel the system. Set the heater to HOT and start the engine. The coolant tube’s bleeder screw should be cracked (see arrow) to “burp air from the line was trapped.
Before removing the pressure cap, let the car cool, and then fill the coolant bottle all the way to the top.
Why is a coolant flange necessary?
The engine coolant temperature sensor, which is typically situated at the back of the engine, is housed in the Coolant Flange. The smell of burning coolant after a long drive or a pink powder-like crust surrounding the coolant flange are two signs that the coolant flange may have cracked.
How much would it cost to repair an Audi A4 coolant leak?
Best in Automotive Repair An Audi A4 coolant reservoir replacement typically costs between $441 and $468. Between $66 and $83 is the expected cost of labor, while between $375 and $385 is the estimated cost of parts. Taxes and other fees are not included in this range, nor are your particular model year or geographic area taken into account.
How much does repairing an Audi coolant leak cost?
You know it’s probably time to hand over the credit card when your automobile starts making odd noises and smells like something is burning. But it might be difficult to determine what repair task has to be done because there are so many potential causes of a coolant leak.
You should budget roughly $700 for an Audi coolant leak repair at a professional. Depending on the year and type of your Audi, the cost might range from $450 to $1200. The source of the leak and its severity are two additional cost considerations.
Fortunately, if you spend a few minutes reading through your owner’s manual or doing some research online, you probably won’t need to hire a tow truck or repair to get the answer.
Every car has an owner’s manual that describes how to care for and service it, as well as any possible early indicators of future issues. This means that you may potentially save yourself thousands of dollars in repair expenses by reading just one portion of your owner’s manual.
There are several potential sources for Audi coolant leaks, including the water pump, radiator, hoses, and gaskets. The typical cost of parts for DIY coolant leak repairs will be around $100.
Although Audi vehicles are frequently praised for their luxurious feel and comfortable ride, the truth is that they can also have regular issues like coolant leakage. Initial detection of coolant leak symptoms in your Audi may be difficult.
We’ll go through some of the most typical causes of coolant leaks in Audis, how much they’ll cost to fix, and some advice on how to do it.
Describe G12 coolant.
Propylene glycol, often known as ethylene glycol, and additional ingredients make up engine coolant. G11, G12, and G13 are the three different varieties of antifreeze. What are the three’s distinctions then? G11 is a silicate base with inorganic additions that is either blue or green. G11 coolant is often used in automobiles made before 1996, although due to its poor heat transfer quality, some vehicles made up to 2016 may also use it. The useful life of this coolant is three years.
Carboxylate and ethylene glycol are the main components of the red or pink G12 coolant. It has an operating temperature range of 90 to 110 degrees and is utilized in high-performance engines. The service life of G12 coolant is 4-5 years. The G12, G12+ (Red), and G12++ coolants are the three different types (Purple). G13 coolant is a hybrid that contains silicate and organic ingredients in the right amounts. The lifespan of this coolant is five years.