Audi S4 B7 Coolant leak Help

[raybrig]

Hi got a coolant leak on the S4, ive found the location of the leak
its a constant drip when parked up over night

its the (silver pipe) that running in front of the oil pan (left to right) its the right side where the pipe attaches to the housing
that has the drip (sorry i dont know what that is yet as not needed to know, coolant pump?)

there is one bolt that holds a (washer) that holds the part in place, im assuming that there is a O-ring inside sealing it
and its this that has failed

id be very greatfull for any help or advise as im needing to to this myself

again i assume that ill have to drain down the system pop this pipe off, replace said O ring ??
and the one on the other side too ??

so id need help with the part number required and place to source, also the drain down method
also any tips on doing this

also coolant 12+ 13 + and the amount the system holds, as if im going to go to the trouble of doing it
best to do it once

also is the car safe to drive after topping up the coolant, as it doesn't leak when warm/driven
i ask this as if i need the car urgent , before getting the parts sourced


thanks for any help or advise in advance

[raybrig]

36676

got a photo up showing the exact location, i assume that ill have to drain down the system and replace the 2 O-ring seals at both ends ??
could do with parts required or links for them

[arman123]

the metal coolant pipe part number is 079121481G

and o-ring is N90806302 for the side in picture

and other side o-ring is 079103121AH

[arman123]

Removing and installing coolant pipe (front)




Special tools and workshop equipment required




t
Drip tray for workshop hoist -VAS 6208-
















Removing




–
Drain off coolant → Chapter (https://ctrl:IDREF=idp41728/).




–
Move lock carrier to service position → Chapter (https://ctrl:IDREF=idp43216/).




https://workshop-manuals.com/audi/a4_mk2/images/a4-11643.png






–
Unscrew bolts -arrows- and remove torque reaction support from engine.




–
Place drip tray for workshop hoist -VAS 6208- under engine.




https://workshop-manuals.com/audi/a4_mk2/images/a4-11644.png






–
Unbolt coolant pipe (front) from engine -arrows-.




Installing




Installation is carried out in the reverse order; note the following:


https://workshop-manuals.com/audi/css/images/hinweis.gif Note


t
Renew seals and O-rings.




t
Secure all hose connections with the correct type of hose clips (same as original equipment) → Parts catalogue. (https://ctrl:ext-dok=idp50960/)




–
Install lock carrier with attachments → Rep. Gr.50 (https://ctrl:ext-rl=idp51952/).




https://workshop-manuals.com/audi/a4_mk2/images/a4-11645.png






–
Allow stop for torque reaction support to rest on rubber buffer for torque reaction support under its own weight and tighten bolts -arrows-.




–
Install bumper cover (front) → Rep. Gr.63 (https://ctrl:ext-rl=idp54864/).




–
Fill cooling system → Anchor (https://ctrl:IDREF=idp56272/).




–
Check headlight adjustment → Booklet803 (https://ctrl:ext-igg=idp57664/) or → Booklet805 (https://ctrl:ext-igg=idp58784/).




Tightening torques




https://workshop-manuals.com/audi/a4_mk2/images/a4-11646.png




Component
Nm


Coolant pipe
Coolant pump
10


(front) to
Sump (top section)
10


Torque reaction support to top section of sump
42


Stop for torque reaction support to lock carrier
28

[arman123]

Draining and filling cooling system


https://workshop-manuals.com/audi/a4_mk2/images/a4-11621.png

Special tools and workshop equipment required




t
Adapter for cooling system tester -V.A.G 1274/8-




t
Pipe for cooling system tester -V.A.G 1274/10-




t
Hose clip pliers -V.A.G 1921-




t
Cooling system charge unit -VAS 6096-




t
Drip tray for workshop hoist -VAS 6208-




t
Refractometer -T10007-







Draining


https://workshop-manuals.com/audi/css/images/hinweis.gif Note


Collect drained coolant in a clean container for re-use or disposal.




https://workshop-manuals.com/audi/css/images/achtung.jpg WARNING


Hot steam/hot coolant may escape when opening expansion tank; cover filler cap with cloth and open carefully.







–
Open filler cap on coolant expansion tank.











–
Release quick-fasteners -1-, unscrew bolts -2- and take off noise insulation.




–
Place drip tray for workshop hoist -VAS 6208- under engine.




https://workshop-manuals.com/audi/a4_mk2/images/a4-11622.png






–
Unscrew drain plug -arrow- at thermostat housing and drain off coolant at engine.




Filling


https://workshop-manuals.com/audi/css/images/hinweis.gif Note


t
The cooling system is filled all year round with a mixture of water and radiator antifreeze/anti-corrosion agent.




t
It is important to use only coolant additive Plus -G 012 A8F A1- (also designated as “G12+”) “meeting specification TL VW 774 F”. Other coolant additives could seriously impair in particular the anticorrosion properties. The resulting damage could lead to loss of coolant and consequently to serious engine damage.




t
“G12+” and coolant additives marked “Meets specification TL VW 774 F” prevent frost and corrosion damage and stop scale from forming. Such additives also raise the boiling point of the coolant. For these reasons the cooling system must be filled all year round with the correct antifreeze and anticorrosion additive.




t
Because of its high boiling point, the coolant improves engine reliability under heavy loads, particularly in countries with tropical climates.




t
Frost protection is required down to about –25 °C (in countries with arctic climate: down to about –35 °C).




t
The coolant concentration must not be reduced by adding water even in warmer seasons and in warmer countries. The antifreeze concentration must be at least 40 %.




t
If greater frost protection is required in very cold climates, the amount of “G 12+” can be increased, but only up to 60% (this gives frost protection to about –40 °C). If the antifreeze concentration exceeds 60%, frost protection decreases again and cooling efficiency is also impaired.




t
Use only clean tap water for mixing coolant.




t
If radiator, heat exchanger, cylinder head, cylinder head gasket or cylinder block have been renewed, do not re-use old coolant.




t
Contaminated or dirty coolant must not be used again.




t
To check frost protection level of coolant additive “G12+” you must use a refractometer -T10007-.




https://workshop-manuals.com/audi/a4_mk2/images/a4-11623.png






–
Install drain plug -arrow- with new seal.




https://workshop-manuals.com/audi/a4_mk2/images/a4-11623.png






–
Fill reservoir of cooling system charge unit -VAS 6096- with at least 12 litres of premixed coolant (based on recommended ratio):




l
“G12+” (40 %) and water (60 %) for frost protection to –25 °C




l
“G12+” (50 %) and water (50 %) for frost protection to –35 °C




l
“G12+” (60 %) and water (40 %) for frost protection to –40 °C




–
Screw adapter -V.A.G 1274/8- onto coolant expansion tank.




–
Attach cooling system charge unit -VAS 6096- onto adapter -V.A.G 1274/8-.




–
Run vent hose -1- into a small container -2-. (The vented air draws along a small amount of coolant, which should be collected.)




–
Close both valves -A- and -B- (turn lever perpendicular to direction of flow).




–
Connect hose -3- to compressed air.




l
Pressure: 6 ... 10 bar.




https://workshop-manuals.com/audi/a4_mk2/images/a4-11624.png






–
Open valve -B- by setting lever in direction of flow.




The suction jet pump generates a partial vacuum in the cooling system.




l
The needle on the gauge should move into the green zone.




–
Also briefly open valve -A- (turn lever in direction of flow) so that hose on reservoir for cooling system charge unit -VAS 6096- can fill with coolant.




–
Close valve -A- again.




–
Leave valve -B- open for another 2 minutes.




l
The suction jet pump will continue generating a vacuum in the cooling system.




l
The needle on the gauge should remain in the green zone.




–
Close valve -B-.




l
The needle on the gauge must stop in the green zone. The vacuum level in the cooling system is then sufficient for subsequent filling.




If the needle does not reach the green zone, repeat the process.




If the vacuum level drops, there is a leak in the cooling system.




–
Detach compressed air hose.




–
Open valve -A-.




The vacuum in the cooling system causes the coolant to be drawn out of the reservoir for cooling system charge unit -VAS 6096-; the cooling system is then filled.




–
Detach cooling system charge unit -VAS 6096- from adapter -V.A.G 1274/8- on expansion tank.




https://workshop-manuals.com/audi/a4_mk2/images/a4-11625.png






–
Fit pipe for cooling system tester -V.A.G 1274/10- onto adapter.




https://workshop-manuals.com/audi/a4_mk2/images/a4-11626.png






–
Pull off rubber seal on plenum chamber cover.




–
Remove plenum chamber cover -1- to front -arrows-.




https://workshop-manuals.com/audi/a4_mk2/images/a4-11627.png






–
Push back protective cover for coolant hoses on connection for heat exchanger.




–
Release coolant hose going to heat exchanger and pull back hose until bleeder hole in hose -arrow- is no longer blocked by the connection.




–
Top up the coolant until it emerges from the bleed hole in the coolant hose without bubbles.




–
Push coolant hose onto connection and tighten.




–
Tighten filler cap on expansion tank.




–
Start engine.




–
Set heater/air conditioner to “HI”.




–
Run the engine for 3 minutes at 2000 rpm.




–
Allow the engine to run at idling speed until the two large coolant hoses at main radiator become warm.




–
Run the engine for 1 minute at 2000 rpm.




–
Switch off ignition and allow engine to cool down.




https://workshop-manuals.com/audi/a4_mk2/images/a4-11628.png






–
Check coolant level.




l
The coolant level can be above the MAX marking when the engine is warm.




Tightening torque




https://workshop-manuals.com/audi/a4_mk2/images/a4-11629.png




Component
Nm


Drain plug in thermostat housing
25

[raybrig]

Thanks very much for the very detailed information, i was really hopeing i could drain the system down and pop off the pipe enough
to fit the new O-ring (to the leaking side)

but it looks like that the whole pipe is ridged, so there would be no (play) in the right side to do this ??

also thanks for the part numbers required, as ive never had to get any parts for the car (except service parts)
it there a easy On-line place to order ??

apologies in advance as ive owned the car for a year but not had to do anything besides service it

ok something i need to ask, the car drives fine it only leaks when its cold (parked-up, very slow drip) would i be able to seal around the housing
with something like silicone to make it water tight (and easy to remove for proper repair) just so as i can drive the car to the garage to get it looked at

the drive is about 40 minutes round trip

very greatfull for any advise

[arman123]

try sealing it and get the seals changed at the garage

ORIGINAL O-ring OEM AUDI VW Audi A4 Avant S4 Cabrio quattro N90806302 | eBay (https://www.ebay.co.uk/itm/ORIGINAL-O-ring-OEM-AUDI-VW-Audi-A4-Avant-S4-Cabrio-quattro-N90806302/303448603746?epid=1219592729&hash=item46a6f23c62:g:PeEAAOSw~15eVuGf)

Seal right OEM AUDI VW Audi A4 Wagon S4 Cabrio quattro A6 allroad S6 079103121AH | eBay (https://www.ebay.co.uk/itm/Seal-right-OEM-AUDI-VW-Audi-A4-Wagon-S4-Cabrio-quattro-A6-allroad-S6-079103121AH/303448603825?hash=item46a6f23cb1:g:usUAAOSwHZBeVt8 E)

[raybrig]

Huge thanks, much appreciated