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Audi A4 Radiator Replacement
 
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Pelican Technical Article:

Audi A4 Radiator Replacement

Steve Vernon

Time:

4 hours4 hrs

Tab:

$110

Talent:

**

Tools:

T20, T30 Torx, 5mm Allen, flathead screwdriver

Applicable Models:

Audi A4 (2002-05)
Audi A4 Cabriolet (2003-06)

Parts Required:

New radiator, coolant

Hot Tip:

Work on a cool car

Performance Gain:

Proper engine temperature

Complementary Modification:

New hoses

The radiators in the Audi A4 like any other car can wear out with time and age. The unit itself is expensive to replace, so before you buy a new one, pressure test the cooling system first and verify the location of any leaks. It will be easier and cheaper to replace a radiator hose or clamp than replacing the whole radiator.

You will need to safely jack up and support the vehicle, remove the front bumper and the under body tray to replace the radiator on the A4 so please see our articles on those projects before beginning work on this project.

A couple of safety precautions/instructions you may want to observe before beginning:

If you cannot work on a cold car allow the cooling system to cool down to a coolant temperature of less than 90°C. Open the cap of the cooling system slowly; turn a conventional coolant cap as far as the first detent and turn a screwed coolant cap approximately 1/2 turn and release the pressure. Wear protective gloves, protective clothing and eye protection. NEVER pour coolant into beverage bottles, cups, etc... Someone might accidentally pick that cup up and start to drink.

If the coolant in the car is new there is no reason to replace it as long as you drain it into a clean container. Coolant is expensive and not too great for the environment, so if the coolant in your car is good, try and save it for reuse.

Before you start, disconnect the ground terminal from the battery and make sure it cannot accidentally make contact with it while working.

With the front bumper removed you can begin removing the radiator.
Figure 1

With the front bumper removed you can begin removing the radiator. Begin by removing the two plastic air trim pieces on both sides of the radiator. Use a T20 Torx and remove the four screws holding the trim pieces to the radiator (red arrows).

After the screws are removed (red arrow), you will need to unclip the pieces from the radiator.
Figure 2

After the screws are removed (red arrow), you will need to unclip the pieces from the radiator.

Either unplug or remove the air temperature sensor from its mount (red arrow).
Figure 3

Either unplug or remove the air temperature sensor from its mount (red arrow). You can squeeze in the end of the sensor and slip it out from the mount or release the clip on the connection and separate the wiring connection.

Slide the air diverter for the intercooler away from the front of the car (red arrow) and use a T20 Torx and first remove the single screw holding the line in front of the condenser in place (yellow arrow) and then use a T30 Torx and remove the single screw holding the line in the front (green arrow).
Figure 4

Slide the air diverter for the intercooler away from the front of the car (red arrow) and use a T20 Torx and first remove the single screw holding the line in front of the condenser in place (yellow arrow) and then use a T30 Torx and remove the single screw holding the line in the front (green arrow). Move the line out of the way.

Disconnect the sensor from the left side of the condenser by releasing the tab and pulling it straight off (red arrow).
Figure 5

Disconnect the sensor from the left side of the condenser by releasing the tab and pulling it straight off (red arrow).

Use a T30 Torx and remove the four screws holding the condenser to the radiator (red arrows).
Figure 6

Use a T30 Torx and remove the four screws holding the condenser to the radiator (red arrows).

Remove the four T20 Torx screws holding the lower air trim piece on the bottom of the radiator (red arrows).
Figure 7

Remove the four T20 Torx screws holding the lower air trim piece on the bottom of the radiator (red arrows). You will need to transfer all the air diverter and trim pieces to the new radiator. With the trim piece gone make sure to support the condenser as it will be hanging free and you do not want to pinch or stress the lines.

Drain the coolant from the radiator.
Figure 8

Drain the coolant from the radiator. On the lower left side of the radiator is a drain valve as well as the coolant temperature sensor. The drain valve is in a very difficult area to reach and it is much easier to slide the clip holding the temperature sensor in the hose connection off and pull the sensor out. If you need additional assistance please see our article on coolant temperature sensor replacement. Be prepared to catch and reuse or dispose of the coolant in a manner in accordance with the regulations in your area.

Release the quick release wire on the lower hose connection (red arrow) and separate the connection from the lower radiator outlet (yellow arrow) by wiggling and pulling the connection straight back.
Figure 9

Release the quick release wire on the lower hose connection (red arrow) and separate the connection from the lower radiator outlet (yellow arrow) by wiggling and pulling the connection straight back. The plastic connections on both the radiator and connections are a known weak point and can break surprisingly easily; use care and take your time when separating.

Here is a classic example of what can happen when separating the connections.
Figure 10

Here is a classic example of what can happen when separating the connections. The overflow hose on the upper left outlet from the radiator was broken on our project car (red arrow). This is a common problem and the leading cause of radiator replacement; again use caution and care when working on the radiator and connections.

Lift the quick release wire on the connection and separate the hose connection (red arrow) from the upper outlet on the left side of the radiator (yellow arrow).
Figure 11

Lift the quick release wire on the connection and separate the hose connection (red arrow) from the upper outlet on the left side of the radiator (yellow arrow).

On the upper section of the radiator are two plastic clips that assist in holding the radiator to the upper cross member.
Figure 12

On the upper section of the radiator are two plastic clips that assist in holding the radiator to the upper cross member. To remove the clips you must first slide the clip on the top (red arrow) over and hold it in place while lifting the plug out from the cross member (yellow arrow). Do this for both sides.

The radiator includes cooling for the transmission.
Figure 13

The radiator includes cooling for the transmission. You will be removing both of the transmission lines from the radiator and some fluid is going to spill out; make sure to place a catch tray under the front of the vehicle. It helps if you can pinch off the line first, but even then a little fluid will escape.

Use a 5mm Allen and remove the single screw on the lower right side transmission line bracket (red arrow).
Figure 14

Use a 5mm Allen and remove the single screw on the lower right side transmission line bracket (red arrow).

You need to separate the line from the radiator.
Figure 15

You need to separate the line from the radiator. They tend to get stuck. Use a large flathead screwdriver, tilt the radiator forward and gently pry the line from the radiator (red arrow).

On the upper right side of the engine bay remove the two fasteners from the cross member (red arrows) and pull the intake air (yellow arrow) from the engine bay.
Figure 16

On the upper right side of the engine bay remove the two fasteners from the cross member (red arrows) and pull the intake air (yellow arrow) from the engine bay.

Use a 5mm Allen and remove the upper transmission line (red arrow) in the same manner as the lower one demonstrated in pictures 14 and 15.
Figure 17

Use a 5mm Allen and remove the upper transmission line (red arrow) in the same manner as the lower one demonstrated in pictures 14 and 15.

You can tilt the radiator forward and then lift it up and out of its mounts on the lower cross member (red arrow).
Figure 18

You can tilt the radiator forward and then lift it up and out of its mounts on the lower cross member (red arrow).

In this picture you can see the two lower rubber grommets that the radiator sits in(yellow arrows).
Figure 19

In this picture you can see the two lower rubber grommets that the radiator sits in(yellow arrows). Note that the A/C condenser is supported by a small piece of rope and is NOT left hanging by the lines (red arrow). Installation is the reverse of removal. Do NOT forget to refill the coolant to the appropriate level.


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Comments and Suggestions:
Blakeusa Comments: Having a hard time getting the trans lines and o rings back together into the radiator both lines on passenger side.. is there a trick to getting the aluminum line back into the radiator?

Should they go all the way in with the oring inside?

Thanks
September 7, 2016
  Followup from the Pelican Staff: Confirm something isn't in the hole stopping the line from going in. Apply clean trans fluid to the O-rings, then be sure the line is straight when pushing it in. - Nick at Pelican Parts  
Allenb6 Comments: Hi when putting back upper return line to transmission after replacement of radiator transmission fluid shot out of line does upper hose sit even mine seems to be slanted going in
Thank you in advance
August 17, 2016
  Followup from the Pelican Staff: I don't understand your question. A line popped out after installing a radiator? Check if the fastener is missing. - Nick at Pelican Parts  

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