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Installing a V8 WJ Grand Cherokee power steering pump in a 5.9 Grand Cherokee ZJ
The power steering pump in my 5.9 was on its last legs, it was becoming difficult to turn at idle, so I decided to swap it out. In the process of putting in a new pump I thought I would try an upgrade. I purchased a PS pump for a 2004 4.7L V8 Grand Cherokee WJ (AC Delco Part# 36P1499 -$78.00+core). I had read on the XJ forums of people using this pump since it puts out more pressure and is an upgrade from the stock pump. The XJ and ZJ pump are exactly the same, the only difference is the reservoir, so I thought it would work on a ZJ as well. The pump looks similar to the stock ZJ pump with some subtle differences. The actual high pressure fitting is substantially larger and the orifice in the fitting is much larger as well. The first you need to do is remove the reservoir on the WJ pump, this will give you access to the high pressure fitting. I removed the fitting with a 1" socket
.You will be swapping in your high pressure fitting from the ZJ pump, so I removed that fitting as well with a 22mm socket. Once the fittings are removed you will see that the actual opening in the WJ fitting is substantially wider than the ZJ fitting.
In order to keep the flow rate similar to the WJ you'll need to drill it out. I simply clamped it in a vice and stepped up in size bits till I finally got to 5/16, which is a little smaller than the WJ opening, but close enough.
After I had drilled it out, and cleaned it I installed the ZJ high pressure fitting into the WJ pump.
Some mis-information that I read about the XJ swap is that you can and should use the XJ/ZJ reservoir so the stock high pressure line will fit - which is false. The ZJ/XJ reservoir will not work on the WJ pump. You can see how there is more material on one side of the reservoir port on the WJ pump vs the ZJ pump, requiring a longer connecting tube on the WJ reservoir.
WJ Pump with extra material on one side of port
Stock ZJ pump reservoir port
The reality is the WJ reservoir works fine with the 5.9 ZJ high pressure hose. There are actually two return ports on the WJ pump. The one that you want to use is the larger bottom one -which you can see with the blue nipple on it.
The second return port is closer to the middle of the reservoir, I simply left it blocked off with the rubber nipple that came on it. The lower return port on the WJ pump is wider than the stock ZJ return port, so I simply stuck some needle nose pliers in the hose and stretched it out. I also upgraded my pulley to a steel one -which is Cardone 3P36147.
Simply bolt it up bleed, and its ready to go!. You can see that the low speed fan switch comes pretty close to the pump, but does not hit.
At a later date I am going to simply rotate the hose coupler up slightly to give it more clearance. It seems to work well, and turns the tires easily at idle.
02-19-2020, 10:28 PM
Installing a V8 WJ Grand Cherokee power steering pump in a 5.9 Grand Cherokee ZJ
