The coolant flange located at the rear of the Audi 1.8T cylinder head is the source of several common coolant leaks. Made of plastic, it bolts to the head with two threaded studs. In improver to property the coolant flange in place the studs support a pair of tubing brackets, including a stand-off bracket for the turbo oil line.

• The flange supplies coolant to ii coolant hoses, and houses the Coolant Temperature Sensor. The Coolant Temperature Sensor is held in place past a u-shaped plastic lock clip and sealed with an o-ring.

• The lower coolant hose has an integral sealing ring. The hose slides onto the lower flange neck, and snaps in place, retained by a metal spring clip that engages mating grooves in hose cervix and flange.

• Here's a right angle view of the same coolant flange, showing the two mounting holes for the head studs. Note the elbow-shaped hose to the right. This hose connects the flange to a steel coolant tube.

• Spend extra time cleaning the mating surface at the rear of the cylinder head where the flange mounts. The flange o-ring needs a clean, flat surface to seal properly.

A spring clench tool makes removing and installing spring-way hose clamps a breeze. Attach the tool and squeeze the handle until it locks in place to expand the clamp. That leaves both hands free to slide the clamp off and on.

A right mixture of pure coolant and distilled water is essential for adequate freeze/boil-over protection and chemical protection against rust, corrosion, and harmful deposits. A refractometer is the most accurate tool for measuring mix ratios.

Refilling the cooling organization can be accomplished without special tools, but nosotros prefer a vacuum refill tool. Just insert the tool's rubber cone into the coolant jug neck and connect the tool to shop air. Switch the valve to pull a vacuum in the system, then motion the valve to "fill" and permit the vacuum in the system suck fresh pre-mixed coolant into the system from a container.

Kit Contents

Your Coolant Flange Kit with Coolant (ES2602886) includes: a new coolant flange with o-ring; attachment studs; an engine Coolant Temperature Sensor with o-ring and plastic retainer prune, and ii quarts of pure coolant.

We have listed related, optional items, available separately, and recommend them for a leak-free repair. These include the 2 hoses fastened to the flange, and a bottle of cooling system flush. If yous are replacing a coolant flange for a leak, expect to find one or both of the hoses at the end of their service life.

You may besides find an unpleasant accumulation of sludge and rust in the system, as nosotros did, so be prepared, particularly if the organisation has been neglected.

Annotation: Depending on whether you car has been apart earlier, you may need to purchase one or more worm mode hose clamps of different sizes to complete this job.

Under the automobile – Step 1

• Remove the expansion tank pressure cap.

• Raise the car and remove the belly pan.

• Drain the coolant.

• Open up the bleeder at the base of the lower radiator hose (arrow) by turning it counterclockwise until the coolant flows freely. (see next slide)

Nether the Car – Step 2

You may demand pliers to turn the drain plug if it is stuck. If it is actually stuck and feels like information technology might break, you lot can pull the clip on the temp sensor (arrow) and remove it to bleed the coolant. Replace the sensor o-ring if y'all have this route.

To avert spilling coolant all over, attach a length of flexible plastic tubing to the drain outlet nipple as yous open the drain-cock. This will direct the coolant flow to a catch can, as we're doing here.
Close the drain when the menstruum stops. Hand tight volition practice.

Nether the Hood – Step three

The coolant flange is located at the rear of the engine, on the rear vertical face of the cylinder head (location indicated by our arrow).
Clearly, nosotros need to remove several items to reach it.

Nether the Hood – Pace iv

Plough each of the three cross-slotted dazzler cover retainer clips a quarter turn to release them; elevator off the encompass.

Under the Hood – Step 5

Components to remove from the right side of the engine include: two metallic tubes, a turbo oil line, and a metal oestrus shield.

We have highlighted their full general location in blue.

Under the Hood – Step 6

• Loosen the hose clamps at either end of the crankcase vent tube.

• Using a 5mm driver, remove the hex head bolts holding the tube to the valve embrace.

• Disconnect the valve from the hoses at either stop and remove it.

Under the Hood – Step seven

Pull the oxygen sensor harness from the servant prune on the heat shield.

Under the Hood – Footstep eight

Utilize an 8mm short socket and ratchet to remove the four servant bolts from the underside of the heat shield.

Nether the Hood – Step nine

Elevator out the rut shield.

Under the Hood – Step 10

Remove the hex caput bolts property the combi-valve tube/purge line tubes to the valve comprehend.

Under the Hood – Footstep 11

Remove the clamps from the hose at the combi- valve and the hose in the purge line next to it (arrows). Our car has worm clamps already installed, yours may have a factory crimp-way clamps that must be cut off and replaced.

Under the Hood – Step 12

Disconnect the tubes and hoses.

Nether the Hood – Step 13

Pull the vacuum hose from the combi-valve.

Under the Hood – Step 14

Using a 5mm hex central, unbolt the combi-valve assembly from the back of the head.

Under the Hood – Stride 15

Note the location of the combi-valve bolts and thin stamped metallic gasket. The gasket will slide off hands, so don't drib it backside the engine as you lot remove (or reinstall) the valve.

Under the Hood – Pace xvi

With the combi-valve out of the way, we can run across the flange at the rear of the cylinder head. There are multiple coolant leaks and everything is coated with coolant crust.
Every bit you can run across, it's a tight fit dorsum here, with a merely a few inches separating the firewall and engine.

Nether the Hood – Stride 17

Rather than fight with the Coolant Temperature Sensor electric connector in tight quarters, pop out the plastic retainer clip with a pick or screwdriver and pull the sensor out of the flange, wiring and all.

Nether the Hood – Step 18

Pulling the sensor up makes it easier to unplug. Press on the release tab and pull at the same fourth dimension to separate the black electrical connector from the sensor.

Circumspection: Inspect the electrical contacts inside the connector for signs of corrosion. Clean with a spray contact cleaner, if necessary. This is a high priority sensor, and the connection must be a good one.

Under the Hood – Pace 19

If yous are re-using the lower hose, attain down and slide the metal clip out of the plastic collar until it hits the stops. Jerk the hose costless from the flange.

Using a 10mm box wrench, remove the two 6mm nuts from the flange studs.

NOTE: The retaining nuts secure tubing back up brackets at top and bottom. The flange will not move, even with both basics removed. The studs must exist removed separately.
(Come across side by side pace for additional photo.)

Nether the Hood – Step 20

Here's a banking company shot photo taken with a mirror so you tin see the servant nut on the flange stud. The lower bracket shown here supports the turbo oil tube.
At that place is another, similar nut on the acme flange stud that holds a purge line subclass.

Under the Hood – Step 21

Before we can popular the oil tube bracket off the lower flange stud, we need to remove the 2 retainer bolts securing the oil tube to the side of the engine. Remove them both with a 6mm hex driver and ratchet (arrow).

When the tube is complimentary, you tin slide the tube rearward far enough to popular its support subclass off the lower flange stud.

Remove the upper nut and pull the upper subclass off its stud.

Under the Hood – Pace 22

Move to the left side of the flange. Follow the long metal coolant tube rearward to the rubber hose (arrow) that connects the tube to the coolant flange.
Disconnect the hose from the flange.

Under the Hood – Step 23

The sometime hose is tired, and a squeeze with thumb and forefinger tell usa it is mushy at the bloated spot indicated by our arrows.

Annotation: This is another example where yous may need to purchase a new worm clamp to supersede the mill crimp clamp afterwards you cut it off (right pointer).

Under the Hood – Step 24

At present we tin unbolt the flange and remove information technology. Using a 10mm wrench, we unscrew both threaded studs and pull the flange.

Note: The lower hose on our motorcar was leaking so badly that nosotros just slit the safe and pulled it off, leaving the coupler on the flange.

Ugh. One look inside the flange tells u.s. that this system needs to be flushed to remove these heavy deposits.

Nether the Hood – Step 25

The coolant jug tells a similar story. Nosotros remove it from the car and flush it with a garden hose.

Under the Hood – Step 26

We will preinstall the lower hose on the flange. Working on the demote makes it a lot easier to button the new hose coupler onto the flange until the coupler prune snaps in identify.

If yous are reusing the old hose, you lot'll accept to make this connexion after the flange is installed on the engine.

Under the Hood – Step 27

Nosotros will also preinstall the Coolant Temperature Sensor.

Slide the new o-band onto the Coolant Temperature Sensor. Then push the sensor into the flange until you tin can slide the plastic servant clip all the way in, as shown.

Slide the nutted-studs into the mounting holes.

Nether the Hood – Pace 28

Clean the flange mounting surface area.

Install the assembly. Hand thread both nutted-studs through the flange holes into the caput. Alternately tighten both to clamp the flange evenly.

Plug in the sensor connector, until it locks in place.

Reinstall both brackets over the nutted-studs and secure them with the 6mm nuts.

Refer to the illustration of page two if y'all need a refresher on component locations.

Finishing Up

At present you tin can start re-assembling the parts removed before.
Hither are a few additional suggestions that may make the job become easier, and forbid futurity bug.

Flushing

If the inside of your cooling system looks like this, take the time to flush it out with a chemic cleaner. (DEI Cooling Arrangement affluent is bachelor from ECS Tuning – ES2608077)

Mix your fresh coolant using distilled water, available at most grocery stores. Shoot for a final l/50 ratio of antifreeze and water for best results.

Using distilled h2o helps prevent problems caused past minerals in tap or well water that settle out and reform as hard calibration. Filling We mentioned the vacuum fill tool on page four. See how it sucks the hoses flat every bit it pulls a vacuum inside the cooling system?

Filling the organisation this fashion eliminates the hassle of "burping" the system to remove trapped air pockets.

Filling and Bleeding Don't have a vacuum fill tool? Then you'll have to practice it the old fashioned way.
Fill the system through the overflow bottle. Start the engine and set the heater to HOT. Crack the bleeder screw on the coolant tube (pointer) to "burp" trapped air from the line.

Run the engine at a slightly elevated rpm until the heater blows hot.

Let the machine cool before removing the pressure cap, then height off the coolant bottle to the max fill line.

Interested in purchasing?

Audi B6 A4 1.8T Coolant Flange Replacement

The coolant flange located at the rear of the Audi 1.8T cylinder head is the source of several mutual coolant leaks. Made of plastic, it bolts to the head with two threaded studs. In addition to holding the coolant flange in place the studs back up a pair of tubing brackets, including a stand-off bracket for the turbo oil line.