Intercooler draining & bleeding for AMS or stock

**BernanksBeard** · 12-09-2015 04:59 PM

I installed my AMS system recently, and wrote this up for a friend. Decided it should be shared. With these techniques I was positive the intercooler loop was air free before ever running the engine. Did have to put the car back on the level ground to bleed the intercoolers.

Draining and filling the S4 intercooler loop
*** before starting, open hood, open and close drivers door to cycle OEM pump. Listen closely, u shouldn't be able to hear any water sounds (trickling/bubbling) Remember how quiet it is when bleeding system later (this also answers the question "how do I know if my system has air in it?")****
1. Open the reservoir cap
2. Open the intercooler bleeders, they don't need to come all the way out, there is a slit through the threads for air. And rubber o-rings under the bleed screws
* notice with bleeder and reservoir cap open, air sucks into intercooler and the coolant level in the reservoir rises. You don't want that to happen under any other circumstance besides draining.
* the intercooler bleeders are tough to open, easy to strip, and plastic. I went through one of those kits with like 20 different Philips bits until I found the right shape to match the bleed screw, I think it was a PZ3 bit. When retightening bleeder just snug it. Heat cycling the engine will make it harder to loosen in future
3. With reservoir cap and both intercooler bleed screws open enough to allow air to suck in, open radiator drain valve and drain until reservoir is empty and stop there and close the radiator drain and reservoir.
4. Then I disconnected a hose to the OEM heat exchanger and fully drained the intercooler loop from the first disconnected hose. It should still be a decent amount of coolant so have a pan ready. You should get some small residual coolant coming from the driver side hose connected to tee under reservoir.
5. You are now ready to do the job..
After completing job and preparing to refill the system, make sure u have a funnel that can seal against the reservoir so u can fill funnel an inch higher than the top of reservoir to finish bleeding. Keep in mind, if installing a divorced system the following doesn't officially apply.
6. This is for AMS system... Open bleeder on AMS tank/pump unit, heat exchanger, OEM reservoir and intercooler bleeders (I never closed intercooler bleeders from when I drained the system).
7. Pour coolant into OEM reservoir slowly and it will also feed and bleed really slow out of reservoir and into the system. Took me over an hour before filling system all the way up to intercoolers, but I'm sure it can be done quicker.
8. Coolant should reach the AMS pump/tank bleeder first, close bleeder and fill until coolant is leaking out of heat exchanger bleeder, then close that bleeder. Then continue filling until OEM reservoir is completely full and 1 inch (or more) above the reservoir. I had my wife hold the funnel down to seal it against reservoir with out making a mess, probably wasn't necessary but my car is spotless and remained so. It takes a while to fully reach the intercoolers.
9. Once u have a steady flow of coolant out of intercooler, close the bleeders. Keep the funnel filled up at this point.
10. Open and close the driver door to activate the pump. You will hear all sorts of water trickling/bubbling while cycling through the system, that's the air moving into all the high points.
11. When the pump shuts off, rebleed from AMS tank, then heat exchanger, then intercoolers. Close them all up and cycle the pump again. Repeat this process until u no longer hear any water sounds. Took me about 5-6 times of cycling pump until fully quiet and I no longer was removing any air. At this point I would bleed intercoolers one at a time.
12. Heater core seems to be as high as the intercoolers, so you probably need to use the funnel. Find the heater core hose with a bleeding hole in it. Pull the hose back until the hole is exposed to the coolant, and bleed.
13. Once satisfied, all bleeders closed, open radiator drain until coolant level is at min line. Then close OEM reservoir cap.
14. The engine loop has its own auto bleeding system and will remove air on its own. Get the car up to full operating temp idling and keep an eye on coolant level. In cold weather, u won't be able to heat up the coolant in the radiator, that is why you won't see coolant expand all the way to Max line. Run full heat and listen for any water sounds.
15. Drive hard trying to heat up all the coolant including what's in radiator and continually inspect coolant levels and keep listening for water sounds. If u can hear water move through the pipes u still have air trapped some where.

When I finished, my coolant level never dropped, so I must have done a pretty good job bleeding it the first time.

For the B8.5 the fog lights made me completely re-route the piping from pump to heat exchanger. I twisted the hose up over top of the secondary air injection pump. I used a heat gun to reshape the SAI filtered return pipe. I have a hard time posting pics on the forum, I'll try it later. Hopefully you guys find this helpful.

**BernanksBeard** · 12-09-2015 05:36 PM

Modified the bracket that holds the pump to allow the hose to come in real tight on that corner. After reshaping the SAI hose, I made my own clamp to hold it in place and prevent any annoying vibration sounds.

**S4'ed** · 12-09-2015 07:20 PM

Or, when refilling, just use a vacuum coolant refill tool (Ebay $60) and be done in 5 minutes.........

**AudiS4TW** · 12-09-2015 10:43 PM

Great write-up!

Sent from my iPhone

**mrmomo313** · 09-10-2016 01:23 PM

Does this sound like air in the system? I probably shouldn't have had the dealer do my coolant flush.. The pump did not sound like this before the flush.

**cspcrx** · 09-10-2016 02:17 PM

That's what my AMS sounds like. High pitch sound when the door is opened. I do notice it changes pitch a bit from when the door first opens.

**mrmomo313** · 09-10-2016 06:18 PM

Yea the pump starts up normally at first but if you listen carefully it starts "chugging" for lack of a better description... Didn't do that before. Have a feeling it wasn't bled properly.

Coolant level is much lower than min after cool down from operating temp. Should be just under min if it was done correctly..

Edit: was just a little airleft in there. Added a tiny bit of coolant and all seems well now.