Front Lower Grill Part Numbers
4A0 807 368 (R), 4A0 807 367 (L), 4A0 853 667 F (Center).
May 28, 2011
October 9, 2010
Replacing the pressure accumulator (“da bomb”)
First and most important, do not confuse hydraulic oil and ATF. They are
not the same thing and ATF in the hydraulic system will ruin the seals.
This WILL lead to leaks in the steering and possibly cause the check
valves in the accummulator to stick. This leads to power brake loss unless
you have a particularly good pump working for you.
Some Audi models DO use ATF in specific systems. Check before you
assume this is safe for your hydraulic system!!!! The reservoir cap
normally specifies which fluid is correct. Also check the owner’s
manual.
The correct fluid is Pentosin hydraulic fluid. This is specified by
both BMW and Audi (proabably others). There are two types. Both are
mineral based although one is called “synthetic.” The primary difference is
the upper bound on temperature range. For the “7.1s” fluid this is 100
c. for the “11s” fluid it is 140 c. 1984 and older model years use the
7.1s fluid. 1985 and newer use the 11s fluid. This costs about $18 to
$22 per liter.
If you have used ATF or hydraulic jack oil in the past, you must get this
out of the system. You can drain the reservior by disconnecting the return
line from the pressure accummulator. Gravity does the job. I used only
one litre of fluid to flush and fill mine. Don’t forget this fluid also
circulates through the power steering. To move fluid here you need to
turn the wheels lock to lock with both front wheels off the ground.
The pressure accummulator (PA) has three hydraulic lines. Two are high
(> 2000 psi) pressure lines, the third (largest) is a return line to the
reservoir. The PA is pre-charged with nitrogen. To change it…
1. Depress the brake pedal repeatedly until you lose assist. Could be 35x
on a new PA. Remove fluid from the reservoir as it fills, if
necessary. IMPORTANT to release pressure, as this system operates
at 2000 PSI!! You can get hurt if you don’t do this!!!
2. The PA is (at least on mine) on the driver’s side. Find it by following
the return line at the bottom of the reservoir. Disconnect all three
lines from the PA. Fluid will come out of the return line so be ready
to catch it. Have a large diameter Philips screwdriver ready to
stick up inside the return line if you don’t want to drain it.
You may also have to put a clamp around the hose and tighten it
slightly – that Pentosin is slippery!!! NOTE: If the fluid is old, why
NOT drain it now???
3. The tip (facing front) of the PA has a threaded stud. Remove the nut.
Lift PA from the back at the return line connection and remove.
4. Some hoses use compression washers; more reccent ones use O-rings
which can be re-used. If washers, install the new one with new
(aluminum) washers if possible, two per banjo nut. These washers
deform to create the seal. If you don’t have new ones, at least
turn them over.
Getting leverage to tighten the banjo bolts can be difficult. A
large pair of (what I call) water-pump or slip-joint pliers can be
handy to hold the PA while getting them tight. You don’t have to
kill them.
5. Fill (and/or flush) see above the reservoir. The reservoir has a center
fine mesh screen that pulls out and can be cleaned. Since filtered
fluid is in the center (and drawn out through the bottom), if you
take the filter out, you might as well clean the canister and get the
dirt out of there. Mine had some very fine oily dust in it that wiped
up very easily.
6. Fill the reservior to minimum and start the car. The PA will now
accumulate fluid and the level will drop as the car idles; it will
take about a pint of additional fluid to top it off. Don’t fill
it to the top full mark, as some fluid returns to the reservoir when
the car is turned off.
7. With the front of the car off the ground, turn the steering lock to
lock five times (as per the manual) to fully bleed the circuit.
8. Check for leaks.
The hydraulic pump supplies two systems: it runs a circuit for the
power steering, and also runs the circuit for the brakes. There is a way
to test a PA by examining the pressure at which the power assist goes
away. Usually on a broken one, this is easy to do since with the engine
off there will be less than one stroke of the brake pedal before assist
is lost. On a weak PA (i.e. one that has lost some nitrogen), it could
be several strokes before loss of assist occurs. The normal minimum
number of strokes is 20. A new one could be 35. That’s what mine is now.
You can decide when it becomes important to replace by measuring the
number of strokes.
Al Powell
UrS4/6 Central Hydraulic Fluid Flush
I was having two annoying problems with my ’94 Audi S4.
1. The red brake warning light indicating low hydraulic pressure would come
on in the morning after the car sat overnight and stay on for 20 seconds or
so. This gradually got worse until the light came on after the car had sat
for a few hours and was staying on longer, indicating the bomb wasn’t
holding pressure and was taking a long time to recharge.
2. There was a “slack” spot at dead centre in the steering where there was
no steering feel or feedback. It felt like worn tie rod ends, but all
suspension components were tight and the rack preload was properly
adjusted.
I solved both these problems by changing the Pentosin in the central hydraulic
system and cleaning the screen in the reservoir.
The procedure I used is as follows:
1. Lift the car (I use ramps) and remove the belly pan. Take the car off the
ramps.
2. Discharge the pressure in the “bomb” (brake servo hydraulic accumulator)
by repeatedly pumping the brake pedal (with the engine off) until the pedal
effort gets hard and the pedal engagement gets very high. It took 48
pumps to discharge the pressure from my 9-year-old bomb. Don’t restart
the engine after the bomb has been discharged. WARNING! Working on a
charged bomb can lead to severe personal injury – pressures exceed
2000 psig.
3. Jack up the left front of the car until the wheel is off the ground. Support
the car securely on a jack stand – you’ll be turning the steering lock to lock
later on in the procedure. I removed the wheel, but it is not necessary. I
left the right front wheel on the ground.
4. Remove the cap and float assembly from the hydraulic fluid reservoir. Put
the assembly in a plastic bag to keep it clean.
5. Crawl under the car and locate the bomb (ahead of the front left wheel
well). It is a black semi-spherical metal container that looks like, well, a
bomb. There is a rubber hose secured with a gear clamp to a barb fitting
on the back of the bomb (see Photo 1). This hose connects to the bottom
of the reservoir. I used it to drain the reservoir.
6. Place a large drain pan under the bomb.
7. Use a pinch clamp on the hose to close it off while you remove it from the
bomb. This is not necessary, but it prevents getting a face-full of Pentosin
or getting Pentosin stains on your favorite Hawaiian shirt. Loosen the gear
clamp and remove the hose from the back of the bomb. Loosen the pinch
clamp and drain the reservoir into the drain pan.
8. Turn the steering wheel lock to lock at least 5 times. This forces the fluid out of the rack – you’ll hear it splashing into the drain pan. When no more fluid comes out, the rack is empty.
9. Remove the screen strainer from the reservoir. This is the plastic tube the float assembly sits inside. Just pull it out – it is not clipped in, the pressure from the spring on the float assembly holds it in place. Note that there are two sets of fine stainless steel screens on the lower end – one on the outside and one on the inside. Flush these well with a degreaser – I used a water-soluble citrus engine cleaner followed by a hot water detergent rinse, followed by a hot water rinse and a methyl hydrate flush to remove the water. Let the screen dry – you don’t want to contaminate the new Pentosin.
10. Add a bit of fresh Pentosin CHF 11S (Audi P/N G 002 000) to flush out the old stuff. Stir what’s left around and suck it out into a vacuum jar. Photo 2 shows the colour of the stuff I took out of my reservoir – this is after it was diluted 3:1 with new fluid.
11. Install the hose back onto the bomb and tighten the clamp.
12. Insert the strainer back into the reservoir.
13. Fill the reservoir with fresh Pentosin CHF 11S (this is the synthetic stuff, not the mineral oil used in pre 1989 Audis). Make sure it is full to the “max” mark. This will fill both chambers in the reservoir. You’ll need about 1.5 litres of new oil for this procedure.
14. Turn the steering wheel lock to lock 5 times. This will fill the rack. Check the reservoir level – it should have dropped. Fill it back up and crank the steering wheel again.
15. When the level no longer falls, make sure it is at “max” and install the float switch and reservoir cap. Put the transmission in neutral and start the engine. Check the oil level and top up – running the engine will pump oil into the bomb.
16. Crank the wheel lock to lock several times to bleed the steering rack. Top up the reservoir to “max”.
17. Shut off the engine. Check the hose on the bomb for leaks.
18. Put the wheel back on, re-install the belly pan, and enjoy!
Fred Munro
’94 S4
September 9, 2002
October 7, 2010
DIY fuel injector cleaning
Very good DIY for fuel injector cleaning. Shows how to clean your injectors and install new filters, “O” rings, pintel caps, etc.
DIY Injector cleaning
Bosch Injector flow rate, part code and resistance table
I got this from a guy off the S2forum.
Bosch Injector Flow Rate & Resistance
Cliff Notes:
Bosch Number: cc/min @3bar Resistance (ohm)
RS2 = 0280150984 359 14.5
Ford Cobalt Blue Top / SVO (94/95 Thunderbird SC/ Mercury XR-7 SC)
0280150968 359 14.5
These figures are not exact like this Electronic Fuel Injector (EFI) Flow Data Table but its another source.
You can find the “0280150968″ Blue Top Ford Injectors (which I believe is also used in the GMC Typhoon/Syclone trucks) cheap ~$100 on Ebay or “cheap” at a junk yard.
Both the Audi and Ford Injectors are the old Bosch EV1 style injectors.
October 4, 2010
URS6 Front Mounted Intercooler for Euro Bumper
Courtsey of audifans.net
Had a couple of days on my knee’s fitting the FMIC kit I gathered up off of Ebay and various suppliers.
Stainless pipes were from Kiowa.
Clamps from Viper-performance.
Samco’s from Ebay user- amberper.
Silicone hose from Ebay user – 1_regals_motorsport
IC from Ebay user – mx5-tuning
Stainless steel and Tig welding – in house 
I also managed to find a decent place for the Power Steering cooler piping to sit – it worked out a treat
I used teck screws to fit it in position using the rubber mount washers, that come with them, as shock mounts for the brackets.
The car will be booked into MRC in the new year for a stage II re-map
Some pic’s below of the proceedings:-
January 8, 2010
How-to integrate an aftermarket head unit with stock Bose components
Thanks to Andrew WK of Audiworld for this.
I decided to go ahead and put together some information for everyone on integrating an aftermarket head unit using the Metra harness. This is using a 1995 S6 Avant with Gamma head unit as an example. I’ve found alot of FUD regarding integration with the stock Bose components, so I figured it was time to layout the facts.
What you need:
1. Metra 70-1785 harness (for easy connection to Audi harnesses)
2. Head unit with 4x >2.2v preamp outputs (for the Bose amp connections)
3. 2x ground loop isolators (prevents popping on track change)
4. High quality crimp tool (for wiring the Metra to your HU harness)
5. 5x Insulated crimp caps 14-18gauge (for the wiring connections)
6. Audi radio removal tools for your car (to get your radio out)
Head unit suggestions:
1. 4x preamp outputs of 4v
2. ability to turnoff internal amp
3. time-delay configuration for each channel
Some key points to note. You will need to wire your power antenna/remote amp trigger connection to turn on/off the Bose amps with the head unit. The GLI’s (ground loop isolators) are connected between the LF/RF/LR/RR pre-amp outputs and the harness connections to each channel on the Bose amps. The GLI’s will eliminate the pop when changing tracks by preventing a discharge of the Bose amps, as modern stereos don’t use common ground. I got a pair from Bestbuy that seem to do a great job. Here’s a picture of the GLI’s installed with the Metra harness (this is a 2-piece harness):
Only 5 connections in the bottom double Metra harness will be used. They are constant +12v (battery), switched +12v (ignition), illumination, Amp Trigger and Ground. I have also labeled a photo of the harness below. Make sure you twist your wire connections tightly. You can solder them too, if you like. Here is a labeled photo of the diagram on the Gamma unit to show exactly which connections are used for the installation:
Backside photo of the 2nd piece of the Metra harness. I removed all the extra wires that weren’t needed.
I’ve built harnesses for a Kenwood with 2.5v pre-amps and the Alpine CDA-9887, which I’m currently using. They both sound excellent with no popping ever (my stock gamma in both cars used to pop occasionally on track changes). The Alpine sounds far superior to the Gamma, especially after configuring balance/fade and the time delay for each channel. I want to try out the Alpine Imprint sound tuning kit with the Bose components. I will update this after I Imprint tune the system to let you know how things turn out, as of right now I see no need to do a Bosectomy. Here’s a finished shot (ignore dust):
The head unit fits perfectly, as the gamma uses a standard sized opening. It just slides right in and maintains a tight pressure fit. You can use the Crutchfield car configuration function to determine stereos that will fit this opening. I’ve tried to include everything, feel free to post any comments or questions and I’ll update accordingly. See my picposter for a few extra photos of stuff.
January 3, 2010
Pictures from Audi Specialist 2Bennett
So I took a day trip to 2Bennett, but they were closed. However I did snap a couple photos. Check them out.
March 21, 2009
Cooling system hose and sensor part numbers with heater core and flap motor info.
Cooling system hose and sensor part numbers with heater core and flap motor info.
After losing a considerable amount of coolant and not wanting to chase leaks hose after hose, I redid all of the hoses, heater core, sensors and plastic stuff in my cooling system. This is a compiled list of numbers and some info I didn’t find anywhere else here, yet.
Thanks to Kevin Day (kday) for his thread from a few years ago with part #’s (which jump started my project), and others threads with all of the info that made my project a success!
MOST IMPORTANT THING HERE: SEARCH! If you haven’t already. There is a huge amount of how to/tips and tricks info on this site about this stuff. A little SFTA and you will have a lot less headaches!
Things I have omitted from here:
-The block to turbo hose connection at the freeze plug, the o-rings on the water manifold and the metal pipes, as they are not common leak points.
-I have omitted the radiator and head gasket part numbers, but they are widely available (FAP99 and AutohausAZ are good sources).
-I also have omitted the water pump as it should have been replaced with the timing belt.
HOSES AVAILABLE FROM MOST AFTER MARKET SUPPLIERS:
4a0 121 101b – radiator to expansion tank and water manifold
4a0 121 109a – expansion tank to water pipe
4a0 121 109b – water pipe (from x-tank) to radiator
4a0 121 055c – thermostat housing to water pipe
4a0 121 055d – water pipe (from t-stat housing) to radiator
N 020 262 1 – banjo fitting on water manifold to turbo coolant line. – I just bought an 8″ piece 5/16″ bulk line from my FLAPS
034 121 063 – block (behind t-stat) to water pipe (heater/after-run pump line)
4a0 121 082 – after-run pump to water manifold
HOSES FROM DEALERS ONLY:
4a0 121 081 – water pipe (heater/after-run pump) to after-run pump
4a0 819 373c – heater pipe to heater control valve
4a1 819 373f – bleeder screw assembly (hose)
4a0 819 371c – heater core to ‘T’ fitting (HVAC sensor port)
4a0 819 371b – ‘T’ fitting to heater flange (on back of block)
HARDWARE:
4a0 819 809 – heater valve
034 121 143e – coolant flange (plastic)
N 900 351 03 – coolant flange o-ring
035 121 113b – thermostat (87′C)
035 121 119 – o-ring t-stat housing
074 121 121b – t-stat housing
443 819 031c – heater core
034 965 561c – after-run pump
4a0 121 403 – expansion tank
025 121 142 – clip for HVAC sensor in ‘T’ fitting
0 132 801 003 – flap motors in heater box (see notes below about this)
4a0 959 101a – blower motor
431 819 225 – heater box gasket (seal between box and bulkhead)
SENSORS/THERMOSWITCHES:
191 959 481c – 2 stage fan switch in bottom of radiator (stock temperature ranges)
054 919 369b – after-run pump switch
034 919 369c – MFTS (Multi-Function ThermoSwitch)
034 919 369m – coolant temperature sensor (ECU)
025 906 041a – HVAC sensor (in ‘T’ fitting)
NOTES:
Some things that might be of assistance:
-The first place to look for coolant leaks that I have found are the after-run pump, expansion tank, t-stat housing/seal, heater flange, heater valve, turbo coolant line and HVAC sensor ‘T’ fitting.
-I had to cut off a lot of my old hoses as they were original.
-The block to water pipe hose behind the thermostat is easier to work with by removing the water pipe. This pipe is bolted on to the transmission bell housing with a 16mm head bolt.
-The replacement heater core I got has slightly smaller diameter intlet/outlet ports. This is fine as the hose clamps can bite down enough to make a good seal.
-I replaced everything in the heater box while it was out ’cause I didn’t want to take it back out again! It is not hard, but is a bit time consuming. It can be removed without removing the center console. Follow the Bentley procedure, but instead of removing the console, do this:
1)remove glove box and both footwell ducts.
2)remove 90′ defroster air duct connector tubes (they snap out)
3)pull heater box out just enough to get at the red and blue flap motor plugs and unclip plugs. I used a small pick with a 90′ bend at the tip as it was hard to get my hand at the right angle to unclip them. Some say that removing the radio makes it easier to get at the plugs but there is a metal bracket in the way on my car
4)heater box can now be removed.
-I used bulk closed-cell foam gasket material from Home Depot for the footwell ducts, panel duct and heater core seals.
-When rebuilding the heater box, I opted to use one type of flap motor. Audi lists a different part number for each of the three flap motors (hot-red, cold-blue and fresh air-black). They are all the same motor with different color/style plugs. Each motor has a different price ranging from $60-$200. I saved about $170 by ordering 3 of the cheapest one (the fresh air motor) and clipping the old plugs off of the old motors (with enough wire left for splicing!) and soldering them on the new motors.
-I used silicone RTV sealant to seal the heater core opening. It stinks. After 3 weeks, it has ‘gassed out’ a lot, but I can still smell it. Probably there is something better out there.
-I used genuineaudiparts.com for my dealer only parts source. They are the least expensive I have found.
I hope this is useful.