A6 C5 Fuel tank removal
#1
A6 C5 Fuel tank removal
I was under time constraints, and didn't get to take many photos.
This is more a procedure than a "how to".
Backstory:
Girlfriend's 2002 A6 3.0 automatic had a fuel smell near the right rear door and/or wheel... worse when driving vigorously, to the point of being evident through the sunroof if the fuel level was high.
The bubblegum recall had been done.
I drove an imaginary slalom pretty aggressively up and down my street a few times and then backed it up on ramps quickly. The right side of the fuel tank was WET with fuel. After examining the flow patterns and working with an inspection mirror, I decided there was a leak on TOP of the right rear "lobe" of the tank. Yay. I couldn't determine any characteristics of the leak with the tank in place beyond approximately where it was.
So I undertook pulling the fuel tank.
Audis being what they are, I had to lie on my back under the car scratching my head for a while to figure out the best sequence in which to remove things in order to get the tank out most effectively.
What I ended up doing was actually lowering the tank about 12" without disconnecting the fuel lines from the car... so it's not really a "removal", but could be by disconnecting 3 more hardlines.
Here's the procedure:
BEGIN WITH A FUEL TANK AS CLOSE TO EMPTY AS POSSIBLE!
1) Raise car. Verify that jack stands will not interfere with fuel tank or filter as it is lowered.
2) Remove nuts from exhaust clamps at forward end of cat-back exhaust (17mm socket, prybar, x4)
3) Loosen and twist/rotate clamps on exhaust pipes to release bond between clamps and pipes
4) Unbolt middle and rear exhaust hangers from body (x8) (13mm socket)
5) Remove exhaust
6) Set parking brake
7) Mark orientation of driveshaft to diff input flange
8) Loosen driveshaft to differential bolts (x6) (6mm hex driver)
9) Release parking brake
10) Remove rear wheels (17mm socket)
11) Disconnect parking brake springs and cables from calipers (prybar, pliers, 3/16" common screwdriver)
12) Remove calipers and use mechanic's wire to hang from brake hard line fitting (15mm open-end wrench, 13mm socket and wrench)
13) Disconnect parking brake cables from control arms (cotter pin puller, 3/16" common)
14) Disconnect parking brake cables from subframe (11mm box end wrench, 13 mm socket)
15) Remove wheel speed sensors from hub carriers (5mm hex driver, prybar, patience)
16) Remove wheel speed sensor wires from clips on control arms
17) Unplug harness connector from ride height switch on left side
18) Remove protective tube from mounting points on subframe (x2) (10mm wrench and flex socket)
19) Bend all wires and cables forward
20) Remove bolts holding spring top plates to body (x2 per side) (13mm socket or wrench)
(approximate time to this point: 2.5 hours)
21) Remove heat shield covering driveshaft (x8 nuts) (10mm deep socket or wrench)
22) Disconnect driveshaft from diff input flange (may require tapping side of CV joint while rotating). Support rear driveshaft on jackstand. DO NOT allow the driveshaft to hang. This will stress the center universal joint and the center support bearing.
23) Support rear suspension with a jack under differential
24) Remove bolts holding subframe to body (x4) (18mm?)
25) Lower rear suspension and remove
26) Unbolt center support bearing from body (deep 13mm socket or wrench)
Note the left/right position of the CSB bracket within its mounting slots. Remember this so that it can be put back in approximately the same position.
(*)When the CSB bracket is removed, put shims and nuts back onto studs from which they were removed
27) Bag and tie driveshaft CV joint to prevent contamination
28) Support center of driveshaft on a jack stand; bagged CV joint may touch ground
29) Remove right rear wheel house liner (Torx T-20(?), 10 mm socket)
30) Remove two bolts holding filler neck assembly to body (13mm socket)
31) Remove panel under spare tire well (x3 acorn nuts) (10mm socket)
32) Remove forward two bolts holding expansion tank to body (13mm socket or wrench)
(*)Leave rearward bolt just started 1-2 threads
33) Disconnect hose from expansion tank on LEFT side of car (opposite filler neck) (large common or 8mm socket)
34) Unclip 5-6 clips holding fuel lines forward of tank to body (3/16" common)
35) Remove rear seat (no tools)
36) Remove fuel pump access panel (x3 screws) (#2 Phillips)
37) Disconnect fuel pump wiring
38) Extricate wire ring from rubber grommet around fuel filler
39) Remove gas cap and use a rag or small towel to plug the fuel filler
40) Push fuel filler into body from outside and unseat grommet around the perimeter
41) Support fuel tank on a jack. I used a 2x8 that fit under the forward end of the tank with a few wood blocks supporting the rear end of the tank. I placed the jack at the overall balance point of the tank and lumber.
42) Remove the support plate and tank strap bolts (x8; 13mm socket)
(*) If you car has had the bubblegum recall done to the rollover valve, the left forward tank strap bolt will require a 10mm 12 point triple square driver and will have an additional shim approx 1/8" thick between the strap and body.
43) Lower fuel tank slowly. The tank must come straight down, but the jack wants to lower it in an arc. You'll have to pull the jack as you lower the tank in order to make sure that it comes straight down.
(Approximate time to this point: 6 hours)
At this point, the tank assembly (which includes the filler neck assembly and expansion tank from under the spare tire well) will be free of the body, but will still be connected to the body by the high pressure supply, low pressure return and evaporative emissions lines at the right front corner of the tank.
When I had the tank dropped, I found the broken nipple shown in the attached photos.
I repaired the nipple with epoxy, then reconnected the hose, built a "containment dam" out of strip caulk and poured the dam full of epoxy to encapsulate the repaired joint. With any luck, it'll never have to come out of the car again...
I hate it when books say this BUT:
Installation is the reverse of removal.
The Bentley says to replace a good many of the bolts we had to remove to do this. I didn't. I reused the driveshaft to diff flange bolts but only tightened them to 25 ftlbs vice the Bentley spec of 41 ftlbs. No problems so far.
I also was not able to find a torque spec for the subframe to body bolts.
More as you ask it and/or it comes to me.
This is more a procedure than a "how to".
Backstory:
Girlfriend's 2002 A6 3.0 automatic had a fuel smell near the right rear door and/or wheel... worse when driving vigorously, to the point of being evident through the sunroof if the fuel level was high.
The bubblegum recall had been done.
I drove an imaginary slalom pretty aggressively up and down my street a few times and then backed it up on ramps quickly. The right side of the fuel tank was WET with fuel. After examining the flow patterns and working with an inspection mirror, I decided there was a leak on TOP of the right rear "lobe" of the tank. Yay. I couldn't determine any characteristics of the leak with the tank in place beyond approximately where it was.
So I undertook pulling the fuel tank.
Audis being what they are, I had to lie on my back under the car scratching my head for a while to figure out the best sequence in which to remove things in order to get the tank out most effectively.
What I ended up doing was actually lowering the tank about 12" without disconnecting the fuel lines from the car... so it's not really a "removal", but could be by disconnecting 3 more hardlines.
Here's the procedure:
BEGIN WITH A FUEL TANK AS CLOSE TO EMPTY AS POSSIBLE!
1) Raise car. Verify that jack stands will not interfere with fuel tank or filter as it is lowered.
2) Remove nuts from exhaust clamps at forward end of cat-back exhaust (17mm socket, prybar, x4)
3) Loosen and twist/rotate clamps on exhaust pipes to release bond between clamps and pipes
4) Unbolt middle and rear exhaust hangers from body (x8) (13mm socket)
5) Remove exhaust
6) Set parking brake
7) Mark orientation of driveshaft to diff input flange
8) Loosen driveshaft to differential bolts (x6) (6mm hex driver)
9) Release parking brake
10) Remove rear wheels (17mm socket)
11) Disconnect parking brake springs and cables from calipers (prybar, pliers, 3/16" common screwdriver)
12) Remove calipers and use mechanic's wire to hang from brake hard line fitting (15mm open-end wrench, 13mm socket and wrench)
13) Disconnect parking brake cables from control arms (cotter pin puller, 3/16" common)
14) Disconnect parking brake cables from subframe (11mm box end wrench, 13 mm socket)
15) Remove wheel speed sensors from hub carriers (5mm hex driver, prybar, patience)
16) Remove wheel speed sensor wires from clips on control arms
17) Unplug harness connector from ride height switch on left side
18) Remove protective tube from mounting points on subframe (x2) (10mm wrench and flex socket)
19) Bend all wires and cables forward
20) Remove bolts holding spring top plates to body (x2 per side) (13mm socket or wrench)
(approximate time to this point: 2.5 hours)
21) Remove heat shield covering driveshaft (x8 nuts) (10mm deep socket or wrench)
22) Disconnect driveshaft from diff input flange (may require tapping side of CV joint while rotating). Support rear driveshaft on jackstand. DO NOT allow the driveshaft to hang. This will stress the center universal joint and the center support bearing.
23) Support rear suspension with a jack under differential
24) Remove bolts holding subframe to body (x4) (18mm?)
25) Lower rear suspension and remove
26) Unbolt center support bearing from body (deep 13mm socket or wrench)
Note the left/right position of the CSB bracket within its mounting slots. Remember this so that it can be put back in approximately the same position.
(*)When the CSB bracket is removed, put shims and nuts back onto studs from which they were removed
27) Bag and tie driveshaft CV joint to prevent contamination
28) Support center of driveshaft on a jack stand; bagged CV joint may touch ground
29) Remove right rear wheel house liner (Torx T-20(?), 10 mm socket)
30) Remove two bolts holding filler neck assembly to body (13mm socket)
31) Remove panel under spare tire well (x3 acorn nuts) (10mm socket)
32) Remove forward two bolts holding expansion tank to body (13mm socket or wrench)
(*)Leave rearward bolt just started 1-2 threads
33) Disconnect hose from expansion tank on LEFT side of car (opposite filler neck) (large common or 8mm socket)
34) Unclip 5-6 clips holding fuel lines forward of tank to body (3/16" common)
35) Remove rear seat (no tools)
36) Remove fuel pump access panel (x3 screws) (#2 Phillips)
37) Disconnect fuel pump wiring
38) Extricate wire ring from rubber grommet around fuel filler
39) Remove gas cap and use a rag or small towel to plug the fuel filler
40) Push fuel filler into body from outside and unseat grommet around the perimeter
41) Support fuel tank on a jack. I used a 2x8 that fit under the forward end of the tank with a few wood blocks supporting the rear end of the tank. I placed the jack at the overall balance point of the tank and lumber.
42) Remove the support plate and tank strap bolts (x8; 13mm socket)
(*) If you car has had the bubblegum recall done to the rollover valve, the left forward tank strap bolt will require a 10mm 12 point triple square driver and will have an additional shim approx 1/8" thick between the strap and body.
43) Lower fuel tank slowly. The tank must come straight down, but the jack wants to lower it in an arc. You'll have to pull the jack as you lower the tank in order to make sure that it comes straight down.
(Approximate time to this point: 6 hours)
At this point, the tank assembly (which includes the filler neck assembly and expansion tank from under the spare tire well) will be free of the body, but will still be connected to the body by the high pressure supply, low pressure return and evaporative emissions lines at the right front corner of the tank.
When I had the tank dropped, I found the broken nipple shown in the attached photos.
I repaired the nipple with epoxy, then reconnected the hose, built a "containment dam" out of strip caulk and poured the dam full of epoxy to encapsulate the repaired joint. With any luck, it'll never have to come out of the car again...
I hate it when books say this BUT:
Installation is the reverse of removal.
The Bentley says to replace a good many of the bolts we had to remove to do this. I didn't. I reused the driveshaft to diff flange bolts but only tightened them to 25 ftlbs vice the Bentley spec of 41 ftlbs. No problems so far.
I also was not able to find a torque spec for the subframe to body bolts.
More as you ask it and/or it comes to me.
Last edited by blaqswan; 07-03-2013 at 12:49 PM.
#2
Photos attached:
-The exhaust out of the car
-My g/f and her conquest
-Under the car where the rear suspension used to be
-The Rube Goldberg rig I built to support the tank in place overnight, yet allow me to slide the jack in and lift it back into position.
-The exhaust out of the car
-My g/f and her conquest
-Under the car where the rear suspension used to be
-The Rube Goldberg rig I built to support the tank in place overnight, yet allow me to slide the jack in and lift it back into position.
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08-03-2013 11:08 AM