2009 A6 3.0T Supercharger Bleed Screws

[QTwo]

HI,

I just completed a thermostat removal and replace on a 2009 A6 with the 3.0T engine. There are a couple of nice write-ups on here and the process was more time consuming vs. high level skills. That is until I went to bleed the coolant system by loosening the PLASTIC bleeder screws/bolts on the supercharger. One came out nicely, the other decided to snap off just beneath the top cap, leaving the balance behind in the threaded hole. Why use a plastic piece on such an expensive automobile versus going with a stainless or brass one?

Below is a post that I had placed in the S4 forum on the thermostat replacement walk-through. I also wanted to have it here to get some feedback from other A6 people and to also have it in here for future reference.
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I was able to complete the thermostat changeout this weekend. Didnt have to remove the water pump pulley and was able to wiggle the t-stat in to place.

Only issue was when trying to remove one of the SC bleed bolt, one of them snapped off. The screw is made of plastic (why?), and trying to use an easy out didnt work. Eventually, I was able to use a tap drill bit and turn it by hand to clean out some of the plastic at the top of the hole. This allowed the lower thread portion to come free from the side of the SC threads, but then the lower portion fell in the SC. Because I had used the easy out which removed the center and then the bit took off most of the top, I dont think much of the plastic went in.

After removing a few small plastic leftovers from the side threads, I was able to thread a stainless M8-1.0 bolt a portion of the way in the SC bleed hole. I met some resistance and didnt push further. The bolt is probably in about 3 turns. I was able to start the engine and the bolt held the pressure without leaking.

A few questions:

- Will this small plastic portion from the previous bolt cause any issues in the cooling system?
- Can I use a thread tap to clean out the bolt threads so I could screw in either a new plastic bolt? How to keep shavings from falling in, I am not sure how many threads need to be cleaned.
- Is the stainless bolt ok to use in place of the plastic? If yes, should I use threadlock and place a rubber o-ring at the top?
- Would the stainless bolt work to "straighten" the threads?

Thanks

[audis4culver]

Just saw your post... I had posted the same exact question for my S4 B8 2011. Bleeder screw bolt head sheared off and I was able to get the threaded portion out but the very end fell into the hole. I was able to force fluid from the reservoir out the bleed screw hole and the plastic tip lodged into the hole. I was so excited to see it that I didnt take my time and with my tweezers I couldnt grab it and it fell back in. After many tries to re-create it .. I never saw it again. So my thoughts are that the piece is left in the intercooler and most likely is wedged into the small fins somewhere. So.. I have convinced myself that hopefully it wont be an issue since fluid is still flowing and has multiple paths through the fins to complete the fluid loop. The piece is so small that I cant imagine it would clog anything.. but that was my question and I received one response saying that I should remove the interncooler core and remove the piece. I did by a new stock screw (8 bucks) from the dealer and I drove the car for the first time this morning and did not see any obvious issues. My wife just bought a 2015 Q7 and it too has the plastic bleeder screw - why they are plastic is nonsense. The fact that it happened to you as well, there must be many others out there that have had this happen.

[05whtaudia6]

i called the dealership, the part is under 3 bucks, i will let you know the part number once i go pick it up. i thought about using a metal screw but perhaps the two different metal wil expand differently under heat, and the plastic screw is so cheap why bother.

[B. Rock]

A couple thoughts:

-There's a heater hose that's underneath the firewall cowl/shroud. This is higher in the system than the supercharger. Why not disconnect and vent/bleed from there?

-What about some gentle heat from a heat gun (NOT a torch)? It would soften the plastic and make it more likely to twist, but maybe less likely to break?

[B. Rock]

As an update, I used an impact and it zipped both of them out no issues - surprising considering the age and mileage (09, 133k).

Also - no need to run the engine to bleed that section, just unbolt the coolant reservoir and lift it up.

[05whtaudia6]

there are three places to bleed the system
1) 1 screw underneath the plenum chamber cove

2) two screws behind the SC
3) one screw under the lock carrier cover.
also a tight fit pipe extension out of the reservoir tank helps keep the fill fluid at highest point or you can use vag 1274/10

[Big_Reyn]

I know this a old thread but does anyone know the size/thread pitch of the bleeder screws. I twisted the head off on one of mine. I am thinking that I can probably find a stronger screw in the hardware store. I didn't realize until after the fact that these engines can self bleed. Also, if anyone can chime in on the best way to remove the messed up screw I would appreciate it.

Sent from my LM-V600 using Tapatalk

[11A6]

I know this a old thread but does anyone know the size/thread pitch of the bleeder screws. I twisted the head off on one of mine. I am thinking that I can probably find a stronger screw in the hardware store. I didn't realize until after the fact that these engines can self bleed. Also, if anyone can chime in on the best way to remove the messed up screw I would appreciate it.

Sent from my LM-V600 using Tapatalk

M8x1 - I actually found aluminum banjo bolts that I'm going to get.

https://www.trialstoreusa.com/banjo-bolt-m8x1-0/

Come in red or black. Much cheaper than the 034

I like the banjo bolts since I dont' have to unscrew the thing very far when I pressurize coolant and the aluminum is the same material at the S/C so I don't mix coolant and two metals,

[tsuengr9]

M8x1 - I actually found aluminum banjo bolts that I'm going to get.

https://www.trialstoreusa.com/banjo-bolt-m8x1-0/

Come in red or black. Much cheaper than the 034

I like the banjo bolts since I don't have to unscrew the thing very far when I pressurize coolant and the aluminum is the same material at the S/C so I don't mix coolant and two metals,

Hello, I just read this post concerning the broken bleed screws in the supercharger. Did the aluminum screws that you purchase from trialstoreusa work ok for you? I am thinking about making the same purchase. Thanks.

[Jake@JHM]

Hello, I just read this post concerning the broken bleed screws in the supercharger. Did the aluminum screws that you purchase from trialstoreusa work ok for you? I am thinking about making the same purchase. Thanks.

These work fantastic: https://jhmotorsports.com/3-0tfsi-su...-a6-a7-a8.html