Where is bleeder on Vw-Audi 4 cyl-1800 engine

In the old days engines used to be built with a bypass cooling system, either by hose or via an internal coolant port. In those days lots of vehicles were produced where the heating and ventilation system was optional and where a heater was fitted the coolant flow would be shut off by a valve during the summer.

Where no heater was fitted or when the heater valve was closed and when the thermostat was closed, the amount of coolant circulating in the engine would be minimal and there would be hardly any circulation through the cylinder head resulting in many problems - hence the need for a bypass system that would allow coolant to circulate through the cylinder block and cylinder head and back into the water pump.

When constant flow heaters were introduced, where heated coolant flows constantly through the heater and the temperature controlled by air mixing, the bypass system became unnecessary and was mostly deleted as it slowed warm up and the flow through the heater was an efficient alternative.

Basically, if there is a bypass it is acceptable to clamp or otherwise blank off coolant flow to the heater.

If there is no bypass the coolant flow must be maintained when isolating the heater, which usually means joining the disconnected hoses together.
As it is a dual heater vehicle, the rear heater will provide the bypass duty so you could simply clamp the hoses to the front heater if it is inconvenient to disconnect them.

I'm assuming for now that these are two separate problems:
1. Overheating and emptying expansion tank.
2. Leak into front passenger footwell.

Solution to 1. is likely to be a crack in the expansion tank. This happens often with these tanks. Look under the cap and you'll find two necks. The narrow one is the pressure tube that the lid seals in to. Check the narrow neck for any cracks and check the pressure cap o-ring for condition. Replace both if suspect. They're cheap from FCP Euro or ECS tuning.
The wider neck is the overflow. This drains into a small tube under the lid area of the tank. You could connect a hose to this if you were so inclined, but it normally it just drains into the engine bay (onto the left hand exhaust manifold normally on V6's!). If yours is losing the coolant from here its a classic sign of a cracked filler neck.
Make sure the cooling system gets bled properly as well - top bleeder is the right hand heater hose (factory hose if still on the car will have a hole marked by a white circle - pull the hose off the heater core connection tube to expose this hole to the coolant, undo and raise the expansion tank above the heater hose level to bleed).
On V6's the lower bleed is on the engine cross flow pipe on the rear of the engine on the opposite end to the engine temp sensor - 6mm allen key undoes from memory. Not sure where lower bleed is on 4 cyl models - possibly the coolant pipe in the vicinity of the inlet manifold.

The other possibility for 1. is a failed cylinder head gasket, but I'd be suspecting the expansion tnk ahead of this. Seek professional help if the expansion tank isn't the issue.

2. I would suggest is a blocked plenum chamber drain. You can check by pouring some water down the windscreen with the bonnet (hood) open and seeing if the plenum area fills up without draining or draining slowly. Main drain is in the middle I think and It gets clogged by leaves and debris. Cleaning is difficult, but you can try a shop vac with some heater hose taped to the nozzle to try and get in there, or some compressed air with an air gun or something to try and blow it through.
Search something like "Audi B5 plenum drains" on Google and you may find some other suggestions.
2. may also be blocked HVAC drains for the airconditioning...

I would do a compression test. Chances are the head gasket blew and thats how the coolant entered the cylinders, and how the hose blew. You may need a head gasket replacement.

bleed cooling system, probably there is air trapped in the heater core preventing warm coolant to circulate into the heater core. try this
1 open radiator cap fill coolant and put heater in hi heat
2 start engine and wait until you see the coolant start to circulate
3 squeeze hose several times watching if coolant volume decrease
4 add more coolant and repeat 3 until coolant volume stays same or start overflowing.
5 check if heater giving off warm air or repeat 3 and 4 until warm air blows on heater.
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or find the coolant bleeder screw, do 1 and 2
open bleeder screw until coolant come out, do this several times until no air comes out when opening bleeder screw, fill coolant in radiator.

possibly a heater hose leak or maybe a freeze out plug

Unfortunately, you are posting the symptom of a failed cylinder head gasket or a cracked cylinder head. When either fail, combustion gasses will enter the cooling system and push the coolant out. As the level inside the cylinder heads drops the remaining coolant will boil and cause it to appear as an overheat. To verify, first, try re-filling the system with the heater on full heat, just to make sure no air is trapped there. If the condition persists, have a hydrocarbon test done on the cooling system. Often you will find coolant in the engine oil or see steam coming from the exhaust pipe. If you have either, that is enough verification to tear the engine down and do some internal checking. Be aware that some of the cylinder heads on the L6 (4,0) engines have casting flaws called micro cracks that tend to show up around 70K miles or more. If you have one, the head should be discarded as junk and replaced.
There is a casting designation that those heads share...unfortunately I don't remember what it is but likely you can research that.
Your electric fans are working...correct?

If you can cut the heater hoses off from the heater core at the fire-wall, and then use a piece of pipe or a hose adapter and hose clamps to join or connect the two heater hoses together, then you can actually drive the vehicle until you require heat from the heater core inside the passenger compartment of the vehicle.

There are vacuum hoses, heater hoses, oil cooler hoses, etc., at the back of the engine. So you would have to tell us. There is no way we can guess. But if it is leaking coolant, it does not make any difference what it goes to. You simply follow it to the ends, remove and replace it, and then top up the coolant again.

only 2 things would cause a leak back there on that engine is a bad heater hose freeze plug blew out! or a blown headgasket

http://www.analogstereo.com/pdf/om/hyundai_tiburon_owners_manual_2003.pdf
• Mark all wiring and hoses to avoid misconnection. • Inspection the timing belt before removing the cylinder head. • Turn the crankshaft pulley so that the No. 1 piston is at top dead center
1. Disconnect the neagative terminal from the battery 2. Remove the engine cover. . Drain the engine coolant. Remove the radiator cap to speed draining. 4. Remove the intake air hose and air cleaner assembly. (1) Disconnect the AFS connector. (2) Disconnect the breather hose from air cleaner hose. (3) Remove the intake air hose and air cleaner. 5. Remove the upper radiator hose (A) and lower radiator hose (B). 6. Remove the heater hoses 7. Remove the engine wire harness connectors and wire harness clamps from the cylinder head and the intake manifold. (1) OCV(Oil Control Valve) connector (A). (2) Oil temperature sensor connector (B). (3) ECT (Engine Coolant Temperature) sensor (C) connector. (4) Ignition coil connector (D). (5) TPS (Throttle Position Sensor) connector (A). (6) ISA (Idle Speed Actuator) connector (B). (7) CMP (Camshaft Position Sensor) connector (A). (8) Four fuel injector connectors (B). (9) Knock sensor connector (C).