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Audi A4 Water Pump Replacement
 
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Pelican Technical Article:

Audi A4 Water Pump Replacement

Steve Vernon

Time:

8 hours8 hrs

Tab:

$50 to $80

Talent:

*****

Tools:

10mm socket, 19mm 12point, 6mm, 8mm Allen socket, flathead and Philips screwdriver, floor jack, jack stands, wheel chocks, safety glasses, torque wrench

Applicable Models:

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

Parts Required:

New water pump and gasket

Hot Tip:

Patience, patience, patience

Performance Gain:

Properly cooled engine

Complementary Modification:

Replace your timing belt

Most water pump failures result in coolant pooling beneath the car. Another sign that the pump is going bad is you'll notice that the car tends to overheat at low engine speed, such as sitting at a stoplight. When you accelerate, the engine temperature will drop. Now, this is not always indicative of a water pump, but a good starting point. You may also want to try squeezing the top radiator hose with the engine warmed up and running (use a glove and watch for heat). You should feel pressure build up on the back of the hose and surge once it is released. If you feel no pressure, it's a fair bet that the water pump is failing.

With Audis, mechanics almost always recommend changing the water pump at the same time as the timing belt. There are two primary reasons for this: 1) it's convenient to change the water pump when the radiator support is already in the service position and you're working on the front of the engine; 2) for a number of years Volkswagen and Audi used plastic impellers, rather than metal ones. These plastic impellers were prone to failure, which would lead to engine overheating.

Replacing the water or coolant pump on Audi A4 is a doable job for a DIY'er but it is not a quick job. If you thought the thermostat was in an awkward and tight spot to work, wait till you see the coolant pump. Give yourself at least 8 hours to get the job done and don't forget to refill the coolant when you are finished.

You will need to begin by safely jacking up and supporting the vehicle, draining the coolant and removing the accessory belt and tensioner. Please see our article on these procedures for further assistance.

There are two covers on the front of the motor protecting the timing belt; the upper (red arrow) and the lower (yellow arrow).
Figure 1

There are two covers on the front of the motor protecting the timing belt; the upper (red arrow) and the lower (yellow arrow).

There are two lines connected to the top of the upper valve cover, a coolant line from the turbo (red arrow) and a vacuum line (yellow arrow).
Figure 2

There are two lines connected to the top of the upper valve cover, a coolant line from the turbo (red arrow) and a vacuum line (yellow arrow). You do not need to disconnect these lines to remove the cover. Just unclip them from their holders. Note: I removed them for photographic purposes

There are two clips holding the upper cover to the head (red arrows); unclip them and pull the cover up and away from the front of the motor.
Figure 3

There are two clips holding the upper cover to the head (red arrows); unclip them and pull the cover up and away from the front of the motor.

You can now remove the upper cover (red arrow).
Figure 4

You can now remove the upper cover (red arrow).

The lower cover contains the witness mark for lining the crankshaft up at Top Dead Center or TDC (yellow arrow).
Figure 5

The lower cover contains the witness mark for lining the crankshaft up at Top Dead Center or TDC (yellow arrow). Before removing the cover and vibration dampener, use a 12-point, 16mm socket and turn the crank bolt (red arrow) clockwise until the mark on the dampener is lined up with the witness mark in the cover.

Make sure that the motor is at TDC for the number one cylinder.
Figure 6

Make sure that the motor is at TDC for the number one cylinder. Check that the witness mark on the head (yellow arrow) lines up with the witness mark on the cam sprocket (red arrow). If they do not line up, rotate the engine until they do. Note: as the belt stretches the witness mark may be off up to 1/2 of a tooth on the sprocket but no more.

Hold the crankshaft bolt in place with a 12-point, 16mm socket (red arrow) and use a 6mm Allen to remove the four dampener bolts (yellow arrow).
Figure 7

Hold the crankshaft bolt in place with a 12-point, 16mm socket (red arrow) and use a 6mm Allen to remove the four dampener bolts (yellow arrow).

Remove the dampener.
Figure 8

Remove the dampener. You may have to give it a few taps with a rubber mallet but never hit it with a metal hammer. The dampener has a locating hole (red arrow) that corresponds with a nipple in the crank (yellow arrow); this insures that the dampener can only be installed one way ensuring proper alignment with the TDC markings.

Use a 19mm socket and remove the five 10mm bolts holding the lower timing cover in place.
Figure 9

Use a 19mm socket and remove the five 10mm bolts holding the lower timing cover in place.

Mark the block (green arrow) and the crank sprocket (red arrow) while the motor is confirmed at TDC, this will save you from having to reinstall the cover and dampener when confirming everything is lined up at TDC for installation of the new belt.
Figure 10

Mark the block (green arrow) and the crank sprocket (red arrow) while the motor is confirmed at TDC, this will save you from having to reinstall the cover and dampener when confirming everything is lined up at TDC for installation of the new belt.

You will need to compress the piston (green arrow) in the tensioner until there is no gap in between the mount and tensioner (red arrows).
Figure 11

You will need to compress the piston (green arrow) in the tensioner until there is no gap in between the mount and tensioner (red arrows).

While holding the tensioner in place with an 8mm Allen (red arrow), use a 13mm socket or wrench and loosen the nut holding the tensioner in place (yellow arrow).
Figure 12

While holding the tensioner in place with an 8mm Allen (red arrow), use a 13mm socket or wrench and loosen the nut holding the tensioner in place (yellow arrow).

With the 13mm nut loose, you will need to turn the tensioner counter clockwise until the piston is compressed and the gap is gone (red arrow).
Figure 13

With the 13mm nut loose, you will need to turn the tensioner counter clockwise until the piston is compressed and the gap is gone (red arrow). The piston is hydraulic and can only be compressed slowly. Take your time and do not expect to quickly force the piston down. If you have the locking tab for the tensioner, you can install it to keep the tensioner locked in the open position. If you do not you can let the piston expand and recompress it when reinstalling the new belt.

Slip the timing belt (yellow arrow) off the coolant pump and remove the three 10mm bolts (red arrows).
Figure 14

Slip the timing belt (yellow arrow) off the coolant pump and remove the three 10mm bolts (red arrows).

There are areas on the coolant pump that you can use a flathead screwdriver and gently pry the pump away from the motor.
Figure 15

There are areas on the coolant pump that you can use a flathead screwdriver and gently pry the pump away from the motor. Do not try and wedge or force a screwdriver between the flush mounting areas of the pump and engine case. Remove the pump from the motor (red arrow).

If you remove the pump to inspect it and are going to reinstall it again, you must replace the rubber O-ring (red arrow).
Figure 16

If you remove the pump to inspect it and are going to reinstall it again, you must replace the rubber O-ring (red arrow). The new pump will come with a fresh O-ring. Installation is the reverse of removal. Do NOT forget to refill the system with coolant.

If you are installing the belt and do not have the locking tab, you will need to slowly recompress the piston in the tensioner (yellow arrow).
Figure 17

If you are installing the belt and do not have the locking tab, you will need to slowly recompress the piston in the tensioner (yellow arrow). Install the belt making sure that the crank and cam sprockets remain on TDC. If one of the sprockets should turn while installing the belt, remove the belt, reset the sprocket to TDC and start over (red arrows).

You will now need to set the proper tension on the tensioner.
Figure 18

You will now need to set the proper tension on the tensioner. There needs to be a gap between the tensioner and tab of 6-10mm. You should set yours at 8mm by using a drill bit to slip between the measuring places (yellow arrows). If the piston is compressed, you can use a set of needle nose pliers or circlip tool to set the distance using the adjuster on the wheel (red arrows). Once the gap is set tighten down the 13mm nut (green arrow). Rotate the engine a few cycles by the crank bolt and recheck the clearance (yellow arrows). If the clearance is more than desired, loosen the 13mm nut and use your 8mm Allen to recompress the piston to the desired gap. If it is less you can loosen the nut and use your needle nose pliers to add gap and then retighten the nut. Make sure you rotate the engine a few times and check the gap and that the belt is aligned properly before putting everything back on the motor. Do NOT forget to refill the coolant.


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