Cooling system
From QuattroWorld Wiki
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 Quattroworld and Audiworld 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 8Insert non-formatted text here19 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. --71.33.203.219 00:59, 8 September 2009 (UTC) Insert non-formatted text here
