slurry pump bearing quick release

How to 4.7L cooling system flush (includes water pump and tstat replacement)

How to 4.7L cooling system flush

I haven't been on the forum a lot lately but my water pump started leaking from the gasket (not the weep hole/bearing) the other day pretty bad so I thought I'd do a quick write up for anyone who needs it. Be sure to follow the service manual steps, but below is how I did the job:

1. Remove lower fan shroud (it just unclips). While laying under the truck, pull apart the splash shield from the upper fan shroud, it’s just three push clips.

2. Unbolt upper fan shroud (2 bolts near the top on each side of the radiator).

3. Unscrew clutch fan from water pump shaft (I used a large crescent wrench with a rag stuffed between the pulley and belt). The 4.7L is regular threaded, lefty loosy. Some people have issues with this step, I did not as I’ve had my fan off before (although, it was never very difficult on mine). Other techniques for removal include a spanner wrench to hold the pulley, clamping the water pump pulley with vice grips, or sticking a screwdriver through a hole in the pulley. Once the fan is unscrewed it’s easiest to drop it out the bottom of the vehicle, but it is possible to shimmy it out the top.

4. Lift and remove the upper fan shroud from the vehicle

5. PRIOR TO REMOVING RADIATOR CAP: Locate and open the radiator drain petcock. It’s on the driver side of the radiator on the bottom. It’s an allen head, it just takes approximately 1 turn or so. Regular threaded, lefty loosy. You’ll feel when it’s open as it will protrude out about 1” and fluid will be draining! Be sure to have a drain pan underneath to catch the fluid. This step (with the system sealed up) sucks and drains the fluid out of the reservoir.

6. Once draining stops, open radiator cap to drain the rest of the system (as much as will gravity drain).

7. Remove the two bolts from thermostat housing (lower passenger side of engine). This will drain most of the remaining coolant. Also, remove thermostat (note orientation for later use), but replace the gasket and reinstall the housing.

8. This next part is optional, but I like to do it:

If you’re water pump is damaged in a way that it shouldn’t run (bearing failure, wobbling, etc) replace it at this time (see step 12 below), otherwise, I like to flush the system with the old pump before installing the new pump.

a. With radiator drain open, and radiator cap off, put a hose into the top of the radiator and fill the cooling system with water. Adjust the water flow to very minimal, just so it will add as much water as is draining out. Put the heater control to HOT, and the fan on (not sure this matters, or what speed, but won’t hurt to put on high), and the vent selector on floor (again, not sure this matters).

b. Start engine and run for ~10 minutes. I waited until it got around 130 deg F. I then left the hose in the radiator and the radiator draining for about another 10 minutes to keep flushing the system and to let the engine cool down a bit before I drained all the water.

9. Next you want to backflush the engine and the radiator (you could say this step is optional, but it should always be done):

a. Radiator: Disconnect the lower radiator hose from the thermostat housing and stick a garden hose into the radiator hose. Tape it up real good to “Seal” it up. Disconnect the upper radiator hose from the engine and turn water on at a low pressure. Don’t overpressurize the system (~14psi) as it could cause damage. I pushed the upper use down so all the water didn’t get all over the engine bay, you could even tape a “drain” hose on if you want to. I left the radiator drain open, doesn’t matter either way though.

b. Engine: (Very important to have the heater OFF so you don’t backflush scale/grime/etc into the heater core). Reattach the upper radiator hose to the engine and disconnect from the radiator. Insert water hose here. Reattach the lower radiator hose to the thermostat housing and disconnect from the radiator. Flush for a few minutes.

10. Take the tension off the belt tensioner and remove the belt (make note the belt routing for later use!)

11. Unbolt idler pulley (pay attention to how tight it is, as I don’t know the torque value for reinstall).

12. Unbolt/replace water pump if necessary for your job. I cleaned the mating surfaces with fine brillo then rinsed off with water and wiped dry/clean with a rag. Water pump bolts are tightened in cross pattern to 40 ftlbs. This was very tight. I used anti seize and I think it lubricated the threads so I didn’t quite go to 40 ftlbs, as I felt like I was going to strip the aluminum.

13. Install new radiator hoses or old hoses if reusing them.

14. Remove air bleeder screw on top of engine near upper radiator hose. This is another allen head. Mine was crazy tight and I was flexing the aluminum housing so I tapped the allen head with a hammer lightly a few times to “shock” it and break the seal on the threads. It then loosened easier.

15. Reinstall idler pulley (I used anti seize). I don’t know the torque for the idler pulley but don’t overdo it. Also, reinstall belt at this time.

16. Fill the entire cooling system with distilled water. Once it starts coming out the air bleed screw, reinstall the bleed screw. Continue filling until full. Reinstall radiator cap. Put the heater on again. Start engine and let run just a minute to circulate the water. Remove radiator cap (BE CAREFUL that it’s not pressurized/hot, as you just ran the engine). Then drain through the radiator and thermostat housing. This will flush out most of the minerals you added by using the hose water.

17. Close radiator drain.

18. Remove air bleed screw.

19. Reinstall thermostat with new gasket. Clean mating surfaces like did with water pump. Note thermostat must go in the correct way, not backwards. Also note there is a hole in the thermostat that allows a little bit of flow even when closed, and this needs to line up with a slot in the housing. Thermostat housing bolts torque to 115 inlbs (13 Nm). I used anti seize.

20. Fill entire cooling system with proper mix of mopar coolant and distilled water. The coolant bottle shows you how to achieve the proper mix. Total capacity is ~14 qts I believe. I poured in ~7 quarts of coolant and it was full, so there was about 7 quarts of water still in the system. Again, once it starts coming out the air bleeder screw reinstall this screw, then continue to fill until full and it stops going down in level in the radiator cap.

21. Suck out any fluid still in the overflow reservoir. Fill to “max” on dipstick with 50/50 mix of coolant/distilled water.

22. Start engine, run through a couple heat cycles (full operating temp to cool) with heater on, and top off the overflow reservoir between each cycle with 50/50 mix of coolant/distilled water.

Check for leaks and monitor temps.

Hope this helps! You can get this job done pretty quick if your really want to, but mine was really overdue for a flush so I took extra time to backflush everything real well. Everything is easily accessible on the 4.7L, it's a pretty straight forward job.