Viscous fan come loose can car be driven - 2000 Audi A4

need to know if the fan is electric or belt driven by way of a viscous fan hub
Of it has a viscous fan hub , while the fan is spinning, it will not be locked up pulling air through the radiator
other indications will be temp up at slow road speeds , high rpm in low gear and boiling off when shutting down

the water pump will be working
what won't be working if fitted is
the viscous fan hub
radiator fans ,
coolant temperature sensor
fan relaypressure test the cooling system to check for cracked plastic tanks of the radiator
fan fuses
blocked radiator cores
thermostat
head gasket
so if the fan is driven by a belt then replace the viscous fan hub
have a compression test done to check head gasket
have an auto electrician check the cooling system electronics and fans
have a specialist radiator shop do a flow test on the radiator and have an accredited service shop check the operation of the thermostat

if it has a conventional fan driven by the belt , replace the viscous fan hub ( fan clutch)
if electric fans . fuses, relays and water coolant temp sensor to be checked
if the over heating occurs at stop lights , slow moving traffic, hard pulls in low gears , and you have a viscous fan hub , it will be the hub

we need to know the make ,model, year and if you have electric fans or fan driven by viscous fan hub
fan belt may drive the fan or just the alternator , power steering water pump but not the fan

have a compression test done to check head gasket
have a flow test done on the radiator
if it occurs at lights , low speed or heavy loads at low speed check the fan operation
if it is shaft driven ( not electric) replace viscous fan hub)

hi
what fan?
heater blower motor or viscous engine fan.
assuming its the latter, you will need a special viscous coupling spanner. fit this spanner correctly and hit it opposite way to engine running. use a copper mallet or similar.
should spin off when loose. refit is opp. dont forget to give it a tap with the hammer.
cheers
Roger

you shouldnt have both. ever you have the thermo fan on the front of the radiator motor side or you have a viscous hub fan coming from a pulley driven by the belt. and ontop of that you should have a little electric thermo fan for your A/C on the other side of the radiator.

I couldn't find the plug or wire on the diagram on my online resource, either. The fan must have a cable going to it to operate, somehow, though, I agree.
Engine Cooling Fan Removal & Installation To Remove:

1. Before servicing the vehicle, refer to the precautions at the beginning of this section.
2. Remove or disconnect the following:
   • Negative battery cable
     
     
   • Fan blade/viscous fan drive assembly from water pump by turning mounting nut counterclockwise as viewed from front - threads on viscous fan drive are right hand. CAUTION
     Do not attempt to remove fan/viscous fan drive assembly from vehicle at this time.
     Do not unbolt fan blade assembly from viscous fan drive at this time.
     
     
     
   • Upper fan shroud attaching hardware
   • Upper fan shroud and fan blade/viscous fan drive from vehicle CAUTION
     Do not place viscous fan drive in horizontal position after removal because silicone fluid in the viscous fan drive could drain into its bearing assembly and contaminate lubricant.
     
     
     
   • Four bolts securing fan blade assembly to viscous fan drive.

To Install:

1. Install or connect the following:
   • Fan blade assembly to viscous fan drive.
     1. Torque to: 17 ft. lbs. (23 Nm)
   • Fan blade/viscous fan drive assembly and upper shroud into vehicle
   • Fan shroud retaining screws
   • Fan blade/viscous fan drive assembly to water pump shaft
   • Negative battery cable

The radiator cooling fan used on the 4.0L engine is
an hybrid fan design. The hybrid fan system consist
of a low speed viscous driven mechanical fan and a
electrical fan.
The hydraulic fan used on vehicles equipped the 4.7L engine, replaces both the electric fan and the engine driven mechanical fan. The hydraulic cooling fan is integral to the fan shroud and is located between the radiator and the engine. The power steering pump supplies the hydraulic fluid and pressure to rotate the cooling fan blade, while the electrical part of the fan is controlled by the JTEC. The hydraulic fan drive (motor) consists of the three major components:
- Steering flow control valve
- Fan control valve
- Two stage G-rotor hydraulic drive
The hydraulic fan and drive is not serviceable.
Therefore any failure of the fan blade, hydraulic fan
drive or fan shroud requires replacement of the fan
module because the fan blade and hydraulic fan drive
are matched and balanced as a system and servicing
either separately would disrupt this balance.

WATER PUMP
The water pump is bolted directly to the engine timing chain case/cover.

A gasket is used as a seal between the water pump and timing chain case/cover.

If water pump is replaced because of bearing/shaft damage, or leaking shaft seal, the mechanical cooling fan assembly should also be inspected. Inspect for fatigue cracks, loose blades, or loose rivets that could have resulted from excessive vibration. Replace fan if any of these conditions are found. Also check condition of the thermal viscous fan drive. Refer to Viscous Fan Drive in this group.

The water pump can be removed without discharging the air conditioning system (if equipped)

REMOVAL
Disconnect negative battery cable from battery.
Drain cooling system. Refer to Draining Cooling System in this group.
Do not waste reusable coolant. If solution is clean, drain coolant into a clean container for reuse.

The thermal viscous fan drive is attached (threaded) to the water pump hub shaft. Remove fan/viscous fan drive assembly from water pump by turning mounting nut counterclockwise as viewed from front. Threads on viscous fan drive are RIGHT HAND. Using special tool spanner wrench 6958 with adapter pins 8346 and a suitable fan wrench loosen the fan drive Viscous Fan and Fan Drive Do not attempt to remove fan/viscous fan drive assembly from vehicle at this time.
WARNING: CONSTANT TENSION HOSE CLAMPS ARE USED ON MOST COOLING SYSTEM HOSES. WHEN REMOVING OR INSTALLING, USE ONLY TOOLS DESIGNED FOR SERVICING THIS TYPE OF CLAMP, SUCH AS SPECIAL CLAMP TOOL (NUMBER 6094) SNAP-ON CLAMP TOOL (NUMBER HPC-20) MAY BE USED FOR LARGER CLAMPS. ALWAYS WEAR SAFETY GLASSES WHEN SERVICING CONSTANT TENSION CLAMPS.

CAUTION: A number or letter is stamped into the tongue of constant tension clamps. If replacement is necessary, use only an original equipment clamp with matching number or letter.

If water pump is being replaced, do not unbolt fan blade assembly from thermal viscous fan drive.
Remove two fan shroud-to-radiator nuts Fan Shroud Mounting Hardware Do not attempt to remove fan shroud at this time.
Remove fan shroud and fan blade/viscous fan drive assembly from vehicle as a complete unit.
After removing fan blade/viscous fan drive assembly, do not place thermal viscous fan drive in horizontal position. If stored horizontally, silicone fluid in viscous fan drive could drain into its bearing assembly and contaminate lubricant.
Remove accessory drive belt as follows: The drive belt is equipped with a spring loaded automatic belt tensioner. Relax tension from belt by rotating tensioner clockwise (as viewed from front) Automatic Belt Tensioner - When all belt tension has been relaxed, remove accessory drive belt.
Remove lower radiator hose clamp and remove lower hose at water pump.
Remove seven water pump mounting bolts and one stud bolt
CAUTION: Do not pry water pump at timing chain case/cover. The machined surfaces may be damaged resulting in leaks.

Remove water pump and gasket. Discard gasket.
INSTALLATION
Clean gasket mating surfaces.
Using a new gasket, position water pump and install mounting bolts as shown. Water Pump Installation - Tighten water pump mounting bolts to 54 N·m (40 ft. lbs.) torque.
Spin water pump to be sure that pump impeller does not rub against timing chain case/cover.
Connect radiator lower hose to water pump.
Relax tension from belt tensioner Automatic Belt Tensioner - Install drive belt
CAUTION: When installing the serpentine accessory drive belt, belt must be routed correctly. If not, engine may overheat due to water pump rotating in wrong direction. Refer to Belt Routing for correct belt routing. Or, refer to the Belt Routing Label located in the engine compartment. The correct belt with correct length must be used.

Position fan shroud and fan blade/viscous fan drive assembly to vehicle as a complete unit.
Be sure the upper and lower portions of the fan shroud are firmly connected. All air must flow through the radiator.
Install two fan shroud-to-radiator nuts Fan Shroud Mounting Hardware
Be sure of at least 25 mm (1.0 inches) between tips of fan blades and fan shroud.
Install fan blade/viscous fan drive assembly to water pump shaft.
Fill cooling system. Refer to Refilling the Cooling System in this group.
Connect negative battery cable.
Start and warm the engine. Check for leaks