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Vortec 4200 Water Pump Replacement - Trailblazer

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Old 02-09-2008, 09:37 PM   #1
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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.

Step 1: Engine bay shot of water pump hidden. Ugh... (LEAVE BELT ON)

Step 2: Remove radiator cap to relieve any pressure.

Step 3: Remove upper radiator hose.

Step 4: Remove both lower transmission lines and 1 of 2 10mm radiator fan shroud bolts.

Step 5: Remove 2nd 10mm radiator fan shroud bolt. Disconnect black clip for fan clutch.

Step 6: 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.

Step 7: Make sure the wrench is clear of the 4 water pump pulley bolts and fan.

Step 8: 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.

Step 9: 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.

Step 10: You might hit the radiator neck, just press shroud towards engine on passenger side and continue to lift.

Step 11: Once removed, loosen (do not remove) the 4 13mm bolts holding the pulley. (LEAVE BELT ON)

Step 12: Remove belt out of the way, and finish removing bolts from pulley, and remove.

Step 13: Remove 5 10mm bolts holding water pump to engine. Prepare for coolant spillage.

Step 14: Remove water pump, and clean old gasket material. Install new gasket and water pump.

Step 15: Install 4 bolts back onto water pump pulley hand tight.

Step 16: Install Belt

Step 17: Snug bolts down

Step 18: 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.

Step 19: 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!

Step 20: Take the hammer back out and give the wrench 3 good smacks back clockwise to tighten nut.

Step 21: Attach 2 10mm bolts back to upper shroud support.
Step 22: Attach 2 transmission lines back to shroud on passenger side.
Step 23: Attach black fan clutch connector on drivers side.
Step 24: Attach upper radiator hose.
Step 25: Start vehicle and let idle. Refill coolant at radiator checking frequently.
Step 26: Put radiator cap back on, and rinse down excess spillage with water.


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Old 09-14-2013, 03:10 PM   #2
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Just thought I'd register so I could post a hearty "THANX" and make a few comments about my experience.

1. The instructions could not have been easier to work with.

2. I read the entire process first, then cut and pasted it into Word. Next, I deleted all the photos, then printed it out. It all fit on one page with the margins set to minimum.

3. The process was SPOT-ON.

4. I found that my radiator top spigot was starting to deteriorate. I HATE plastic radiators.

5. Wiggling the fan & shroud assembly out was a bugger, getting it back in was worse!

6. I had to chock the pump pulley with a heavy screwdriver nuts and the shaft slipped between one of the to keep it from turning as I smacked my big wrench to knock loosen the big nut for the fan clutch.

The whole process took me about 2 hours including a quick run to the parts house to pick up the parts, and a test run back again to pick up a can of R-134 to charge up my A/C.


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