Audi S6 Cooling System Repair

Audi S6 Cooling System Repair

Well, the cooling system is not cool. In fact, it’s so uncool that it burned me when trying to drain the water after 5 minutes of idling. This will not do. When attempting to start the car it starts just fine but the temps are off the charts in no time at all. I suspected there may have been a reason the car was relatively cheap but I didn't expect this.

I anticipated that perhaps there is a blockage or an air bubble in the cooling system that is causing it to act up. There is also something funky going on with the heater core valve, which had been “fixed” by a previous owner. This includes a straight-through pipe rather than an actual valved heater core mechanism, meaning there is no actual control to the heater core. There is also no water going into the heater core as the car does not blow hot air, only AC.

I started off with flushing the coolant a bunch. A bunch. After about 30 gallons of water, I decided it was time to just hook up the hose, as the coolant kept pumping out bits of rust and rock. I ran some coolant system cleaner and these are the results. Note the sediment deposits everywhere and the massive amount of calcium film on everything.

Yes, this was a layer of goop. Yes, it was disgusting. Imagine your engine running with this inside of it at all times. No wonder the thing barely ran.

There were so many little bolts and screws that I will surely be missing some as it goes back together. Following this, I hopped on and ordered a bunch of new parts, including a new heater core and radiator. In the meantime, I repainted the support beams on the front of the car and the intercooler.

Note the absolute state of this water. Brown and filled with rust. After hours and hours of flushing it finally cleared up, which you can see in the final picture above. The heater core and radiator 100% had to be replaced and that is what we ended up doing. I will make another post about the heater core process. I also purchased a new thermostat housing as the previous one was pretty jacked up. Note the giant gash in the new radiator from shipping.

So I put it back together. And well… now there’s a new leak. After getting the whole front end back together and all the piping back on, there pressure tester is not building any pressure in the system. I added some water and the car is leaking from above the oil pan, which would seem to be the thermostat housing. Back to the drawing board, but at least the water is clear now.

Received my new valve replacement from Lithuania after three months. Please ignore the orange silicone. This was a slight oversight when I filled in the heater core.