riotburn

*Disclaimer - I take no responsibility for any damage to your car, this is only meant to be a guide *

This is my first try at a DIY writeup. Just changed my thermostat and flushed the coolant on my 99.5 A4 with an AEB. This article is pretty much based off of xqwizit's write up (http://audiforums.com/forum/showthread.php?t=127029). The difference is I am more of novice and need visuals to understand so I'd thought I add this here.

Step 1: Take off cap from coolant resevoir tank.
Step 2: Take off trim to the left of the drivers side fog light.
Step 3: As seen in the first picture below, pull the rubber piece from the top left corner diagonally down to expose the drain plug.
Step 4: The drain plug is red plastic with a plus sign for a screwdriver located where the red circle is in the first picture below. You have to get at it with an angle but it'll open. Open all the way to drain the fluid. Don't pull it out though, its difficult to get back in.
Step 5: Underneath the car on the drivers side of the oil pan lookup to find the thermostat housing, a black hose with 2 10mm screws (labeled 1) holding it on. There is a support in the way of the screws. So as seen in the second picture below, remove the 14mm nut (labeled 2). Then loosed the 6mm hex (labeled 3) and swing it out of the way. (You can get at it without removing the support but I chose not to)
Step 6: Remove the 2 screws for t-stat housing. Careful when you pull it off because more coolant will come out. Then pry out the thermostat.
Step 7: Put the new O-ring on top of the housing, then the thermostat. (On the black part that came off, I did it the other way around first and had water leaking out while flushing the coolant)
Step 8: Put everything back together, and fill with a 50/50 mixture of the pink stuff and water.

Enjoy!

straggler7

Thank you. i am a newbie and this was very helpful.