Audi Parts Catalog Audi Accessories Catalog Audi Technical Articles VW-Audi Tech Forums
 
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
 >  >
Coolant Expansion Tank Replacement
 
Bookmark and Share

Pelican Technical Article:

Coolant Expansion Tank Replacement

Jared Fenton

Time:

1 hour1 hr

Tab:

$100

Talent:

***

Tools:

Small fluid pump or turkey baster, hose clamp,

Applicable Models:

Audi A6 (1997-04)
Audi A6 Quattro (1997-04)
Audi S6 (2002-03)

Parts Required:

Coolant Expansion Tank

Hot Tip:

Try to get as much coolant out of the tank as possible

Performance Gain:

Proper function of cooling system

Complementary Modification:

Replace engine coolant

The coolant expansion tank (CET) is one of those items that tends to start failing in cars with higher mileage. The CET has a manufacturing seam that can split due to the constantly changing temperature and pressure conditions inside the cooling system. Take a look around the CET for tell-tale signs of coolant leaking from the seam. If you do find a leaking CET, replace it as soon as possible. The good news is that replacement is easy and should take no more than an hour.

Remove the cap on the CET and check the fluid level. You'll need to remove any fluid left in the CET prior to removing the tank, otherwise it will just spill out all over the floor when removing the hoses. Remember that coolant is highly toxic to animals and the environment. Care should be taken if you are not going to recycle your coolant!

The method I like to use is a simple aftermarket electric fuel pump. These are readily available at any good auto parts store for around $20. I connect the fuel pump inlet hose down to a small diameter plastic hose that allows me to slide it inside the CET and get as much coolant out as I can. The outlet of the pump simply feeds into a clean 5 gallon container. The nice thing about this method is that it allows you to simply pour the existing coolant back into the system when you are done. You can even use a turkey baster to remove the coolant. It just might take a bit longer and might be a little messy.

If your CET has been leaking badly and there is a significant amount of coolant lost from the system, a vacuum bleeder is a must have item. In these cases, air usually gets into the system and there really isn't a way to bleed it out manually. A vacuum bleeder allows you to evacuate all the air from the system using a vacuum. You then use the vacuum inside the cooling system to draw the coolant in. All things being equal, you should have just enough coolant inside the system when the pressure inside the cooling system equalizes. See our article on Coolant Flush and Replacement for more information. You'll also need to remove the right side engine cover. See our article on Engine Cover Removal for more information.

Shown here is a new coolant expansion tank courtesy of Pelican Parts.
Figure 1

Shown here is a new coolant expansion tank courtesy of Pelican Parts. Often times, the new tank includes the level sensor. You'll want to check this before ordering.

Shown here is the location of the CET on the C5 Audi A6 2.
Figure 2

Shown here is the location of the CET on the C5 Audi A6 2.7T. Unscrew the pressure cap (purple arrow) and suck out as much fluid as you can from the tank. The idea here is to prevent a big spill when disconnecting the lower hose to the CET. Use a small fluid pump or a turkey baster along with a clean container. This way, you can pour the fluid back into the CET if you aren't replacing the fluid. Loosen and remove the three Phillips head screws (green arrows) and carefully lift the tank up to access the components below.

You'll now need to remove the coolant level sensor electrical connector.
Figure 3

You'll now need to remove the coolant level sensor electrical connector. On our project car, this was missing; however you can see the tab on the tank (green arrow). Press the tab on the electrical connector and pull it off.

Squeeze the tabs (green arrow) on both sides of the drain overflow tube and pull it off the tank.
Figure 4

Squeeze the tabs (green arrow) on both sides of the drain overflow tube and pull it off the tank.

Loosen and remove the hose clamp (green arrow) holding the lower hose to the CET.
Figure 5

Loosen and remove the hose clamp (green arrow) holding the lower hose to the CET. Be prepared for some coolant to spill out.

Now loosen and remove the hose clamp holding the upper hose connection to the CET (green arrow).
Figure 6

Now loosen and remove the hose clamp holding the upper hose connection to the CET (green arrow). At this point, you are ready to install the new CET. Installing it is the reverse order of removal.

Once the new tank is installed, make sure that the coolant level sits at the correct position indicated by the arrows on the tank (green arrow).
Figure 7

Once the new tank is installed, make sure that the coolant level sits at the correct position indicated by the arrows on the tank (green arrow). If done correctly, you shouldn't have to bleed the system.

Bookmark and Share

  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Project/Wish List]
  [Privacy Statement]  [Contact Us] [About Us] [Shipping] [Careers]

Copyright © Pelican Parts Inc. -    DMCA Registered Agent Contact Page

Page last updated: Fri 12/9/2016 03:02:03 AM