WJ Waterpump Replacement Write Up

[Brad S]

WJ Water Pump Replacement
4.0L I6

If you are like me, then replacing a water pump doesn't sound like that much fun, but you would rather do it yourself than pay someone else to do it.
Replacing the water pump on your WJ isn't going to be that hard, but a little help with the steps would probably be nice.
This write up will hopefully give you some pointers that could save you some time in the long run and make things a little easier for you.

1) Diagnosis. First thing you probably have noticed is that puddle of antifreeze on the ground in the morning. Check your hoses first and try to determine where the leak is coming from. If it is indeed dripping down the front of the engine block, check your hoses on the water pump and thermostat housing once again, just to be sure (no sense in doing more work than necessary here). If you are in the same boat I was, water and coolant is probably seeping out of the weap hole of the water pump. This is a good sign that your water pump is on its way out.

2) Replacement.

First drain your radiator. There is a petcock drain on the lower, passenger side of your radiator. It should have a rubber hose attached. I found that a little duct tape to secure the hose straight against the shroud makes it easier to drain it into a antifreeze bottle or container.

When you look at the top of your engine this is what you will see:



Not a lot of room at all between that fan shroud and the pulleys. You could possibly do the job with the fan shroud on, but I would HIGHLY recommend that you remove it - it will make your life a lot easier.

Before you remove the fan shroud, you should unbolt the fan clutch and fan from the water pump pulley. If your water pump pulley does not have any holes in it for a special tool, your best bet for removal is probably the hammer and crescent wrench. With the pulley belt still on, get a large crescent wrench and grip the large fan clutch nut. You will need to hit it several times to knock it loose. The trick to finding out which way the nut needs to turn is to watch which way the fan spins while the engine is on. Hit the nut the same way the fan spun. My fan spins counter-clockwise, thus, the nut broke loose by me hitting it counter clockwise. Once you break the large nut loose, unthread it all the way and set it down in the fan shroud.




To remove the fan shroud, you must first remove 2 radiator hoses. The top one is on the passenger side, just squeeze the clamps, pull it off and bend it out of the way. The lower one is on the driver's side, do the same.

Next, you will need to remove the 4 bolts securing the fan shroud. The picture below will indicate where they are located. Be sure to unplug the plug from the shroud as well.



You may wonder how they even got the 4th bolt screwed in during assembly, let alone how to get it back out. Some people have said that a socket with a few extensions did the trick, but with my WJ, there wasn't enough room between sheet metal and the bolt to get a socket in there. I found just by sticking my hand through lines and hoses and using a open ended wrench that I could slowly turn it out. When putting them back in, I took one look at the situation again, tested the shroud for secureness and then scrapped the 4th bolt. I figured it would be OK without it.

Once you get the 4 bolts out, you will need to work the fan shroud and fan, up and out the top of the engine compartment. Doing this will create a VAST space for you to work in.

This is a picture of the engine once you get the shroud and fan out of the way. Note, these pictures were taken on the reassembly process, so the water pump is new and the blue rubber cap is just to protect the new threads.



To get the old pump out, you will need to remove the the small hose connected to the metal tube coming out the top of the water pump. You can leave the intake hose on for right now and pull it out with the water pump. Once you disconnect the small hose, remove the 5 bolts that hold the water pump to the engine block. Be sure and keep track which holes they went in as they may be different sizes. In the picture below, you can see the old water pump, the pulley, and the metal tube as well as the locations of the 5 bolts.



Once you get the 5 bolts removed, you may have to gently tap the water pump itself with a mallet or hammer to get it to break free from the old gasket. Be sure to have a pan below the engine to catch coolant as more will poor out at this point.

When you have the old pump out, remove the pulley's 4 bolts and set it aside for reassembly. Also, remove the metal tube and set it aside as well. Examine it for corrosion and possible replacement. Mine was in good shape so I reused it on the new pump.

The next step I did was to remove and replace the thermostat as well. This is optional, but since you have it all apart, you might as well replace it since it's only a few bucks extra.

Remove the output tube as well as the small rubber hose and disconnect the sensor from the thermostat housing. There will be 2 bolts holding the housing on. Remove those and gently tap the housing to break it free from the gasket. More coolant will drain.



Be sure to THOROUGHLY clean all surfaces where new gaskets will be mated. Here is a picture of the thermostat housing after I cleaned its surface.



At this point, remove the thermostat (remember how it was positioned) and clean all gasket material from the thermostat housing area as well as the water pump. I used some degreaser and a exacto blade for the gasket material. Be sure and clean it really well and use a rag to wipe off any cleaner or coolant. Before installing new parts, make sure any old gasket material that may have fallen into the engine channels is removed.



Cleaned water pump surface.



Once you have reached this point, it is pretty much a matter of retracing your steps to install everything again. Insert the new thermostat in the same position as the old one was and reinstall the housing with the new gasket. Use a small ammount of RTV on the new gasket to hold it to the housing while mounting it. When installing the water pump, use a small ammount of RTV as well to hold the new gasket to the new water pump. Also be sure to install the metal tube before mounting the pump. I used some high-temp sealant on the threads. According to the FSM, torque the bolts to 17 ft lbs for the I6 and 30 ft lbs for the 4.7L V8.

Place the fan shroud back in the engine compartment with the fan inside just like removal. Thread the large nut back on until snug and gently tap it with the large crescent wrench. Don't try to force it tight, the engine turning the pulley will keep it on.
Reinstall the nuts to the shroud and all hoses and fill your radiator back up. Be sure to run your engine and purge the air from the system as well.

That's about it, overall the process isn't to hard. If you have any questions feel free to contact me.
Good luck on your replacment!
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[Orangeamc13]

On the disassembly, don't you have to remove the pulley from the water pump before you can remove all five of the pump bolts?
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83 CJ7 4.2, 88 XJ 4.0, 94 ZJ 5.2, 99 XJ 4.0
UNDERGROUND JEEPS

[Brad S]

I'm trying to remember... You may have to. Good Call
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[Orangeamc13]

Nice writeup Brad!
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83 CJ7 4.2, 88 XJ 4.0, 94 ZJ 5.2, 99 XJ 4.0
UNDERGROUND JEEPS