I have coolant leaking out of the fan pulley. why?

Probably the water pump. You should see coolant coming from the vent hole on the pump--usually on the bottom.

Not likely. Idler pulleys are only for routing of the serpentine belt. If one of your "pulleys" is leaking coolant its likely the water pump, which also has a pulley on it. The smoke is probably leaking coolant burning off a hot part of the engine or exhaust system.

Clean off all rust,oil,coolant,etc from all pulleys

Check for coolant leaks, such as water pump or the
bottom crank damper, motor oil leaks

If no leaks,try turning the belt around

Do not spray anything on it,it should be dry

probably the water pump. front and center of the engine, the pulley that may or may not have the cooling fan attached. from under the truck a leaking water pump usually leaves some coolant residue on the timing cover and at the front of the oil pan where the wiring harness come across.

Remove or Disconnect

1. Coolant from the radiator.
2. Multiple ribbed drive belt.
3. Upper fan shroud.
4. Fan and fan clutch assembly.
5. Coolant pump pulley.
6. Radiator outlet hose clamp and hose.
7. Bolts and stud.
8. Coolant pump.
9. Gasket(s). Inspect

• All parts and replace as necessary.

Important

• Be sure all mating surfaces are free of burrs or other imperfections.

Install or Connect

1. Gasket(s) in place.
2. Coolant pump.
3. Bolts and stud.

• Sealant (GM P/N 1052080 or equivalent) must be applied to the bolt threads.

Tighten

• Bolts and stud to 41 N.m (30 ft. lbs.) , 4.3 engines.

1. Radiator outlet hose and clamp.
2. Coolant pump pulley.
3. Fan and fan clutch assembly.
4. Multiple ribbed drive belt.
5. Upper fan shroud.
6. Coolant to the radiator. Important

• Start the engine and check for leaks.

Lets start with pressure testing the system and looking for leaks. ( you need a pressure tester for this)
After you do thistake accessory belt off of water pump
and with one hand grip the water pump pulley and see if you can get it to move up or down. If it move or is leaking coolant by the weep hole (Usually found under the pump)
replace it.
If no leaks were found and the pump didn't fail the bearing test( pulley movement)its time to test the fans.
remove the electrical connectors on each fan and make a pair of jumper cables and jump the fans directly to the battery. If they run swell if not replace the one that didn't run.
Next check coolant temperature sensor (CTS)and its circuitry for continuity and resistance. Use the Shop manual for testing of CTS, relay and its circuitry.
Replace items that fail testing.

You need to locate the water pump. It is turned by a fan belt. There should be water hoses running into and out of the pump. Water pumps have a weep hole that leaks water when the pump starts to fail. It is usually hard to see as it is behind the pulley for the fan belt. If you're seeing a leak in this area it is a pretty good chance that the pump is bad and needs replaced.

water pump

it is not the crank pulley it is the water pump above the crank pulley, the coolant runs down and looks like it is from the pulley area.

drain engine coolant.relieve belt tension .and remove the drive belt.remove upper fan shroud.remove fan or fan and clutch assembly.remove water pump pulley and coolant hoses from water pump.remove water pump bolts.then remove pump from engine.pay attention to bolts location because they are different lenghts.clean water pump gasket mounting surface dont scratch .or pump gasket wont seal and leak .apply sealant to water pump bolts.install water pump with new gasket.if gasket paper put a sealant on it.torque water pump bolts to 30 ft lbs.if you got a 2.2L engine torque water pump bolts to 18 ft lbs.install coolant hoses on pump .install water pump pulley.install fan and fan clutch assembly.install the drive belt .and the upper fan shroud.fill the radiator with coolant.then run engine to check for leaks.WARNING AS A SAFETY PRECAUTION REMOVE NEGATIVE BATTERY CABLE SO CAR WONT BE CRANK BY ACCIDENT. ALSOOOO DONT FORGET TO TURN OFF RADIO FIRST BEFORE DISCONNECTING BATTERY SO YOU WONT LOSE YOUR RADIO CODE.