Water pump replacement on Vortec 4200 Engine residing in a Trailblazer. I started hearing a grinding noise in the front. After investigating I found that the water pump was failing. The fan and water pump pulley could be moved around by hand. So it was time to replace.
Total time spent was 30 Minutes. I didn't drain the coolant. I only used a catch pan.
Engine bay shot of water pump hidden. Ugh... (LEAVE BELT ON)
Remove radiator cap to relieve any pressure.
Remove upper radiator hose.
Remove both lower transmission lines and 1 of 2 10mm radiator fan shroud bolts.
Remove 2nd 10mm radiator fan shroud bolt. Disconnect black clip for fan clutch.
Make sure hood is propped up nice and high. I used a pry bar and wedged it. Get an open ended wrench to fit the fan clutch bolt. I used a 1 1/2". (Those specialty tools are junk). Its a little bigger, but all I had. Still worked fine.
Make sure the wrench is clear of the 4 water pump pulley bolts and fan.
Get a firm grip on the wrench, and take a hammer and smack it 1 good hard time to bust the nut loose. Make sure the hood prop is not up.
Spin nut off and press in on fan to lift over the threaded end. Continue to lift upward on the fan and shroud at the same time to remove as 1 unit.
You might hit the radiator neck, just press shroud towards engine on passenger side and continue to lift.
Once removed, loosen (do not remove) the 4 13mm bolts holding the pulley. (LEAVE BELT ON)
Remove belt out of the way, and finish removing bolts from pulley, and remove.
Remove 5 10mm bolts holding water pump to engine. Prepare for coolant spillage.
Remove water pump, and clean old gasket material. Install new gasket and water pump.
Install 4 bolts back onto water pump pulley hand tight.
Snug bolts down
Start and check for leaks. Now is the time to replace the fan clutch if necessary. Check engine will illuminate until fan clutch is reinstalled.
No leaks, Great! slide fan shroud and fan back in as 1 unit. Wiggle around the upper neck until it seats back. Press in on the fan until it goes back over the threads of the new water pump, and tighten back down spinning the nut clockwise. Adjust the fan shroud for the proper alignment. MAKE SURE THE 2 LOWER TABS ARE PLACE BACK IN THEIR POSITIONS!
Take the hammer back out and give the wrench 3 good smacks back clockwise to tighten nut.
Attach 2 10mm bolts back to upper shroud support.
Attach 2 transmission lines back to shroud on passenger side.
Attach black fan clutch connector on drivers side.
Attach upper radiator hose.
Start vehicle and let idle. Refill coolant at radiator checking frequently.
Put radiator cap back on, and rinse down excess spillage with water.