WJ Steering Pump - loud and frothy

I replaced my stock pump with a used unit off of a 4.7 WJ. Originally I left the high pressure fitting from the XJ pump alone and had no problems. Eventually I bored out the XJ fitting to match the diameter of the WJ one as others have done because I felt no real gain in steering power with the previous setup. Now the pump whines and groans. I have bled the system with the wheels off the ground turning the wheel lock to lock numerous times until no more bubbles appear in the reservoir. After driving around for a few minutes the steering will start to groan and the fluid in the reservoir is frothy.

I’ve gathered from reading threads of others that have done the swap that the fluid cavitation is occurring for a couple of different reasons:

I have the return line plumbed to the 3/8” port in the side of the reservoir and not the ½” one on the bottom and the smaller diameter of that port could be causing the cavitation. Not sure how switching the inlet ports on the reservoir would help as the size of the line coming out of the steering box is still 3/8”.

There is air being introduced into the system somehow, possibly in the connection between the reservoir and the pump. There are no visible leaks on my pump, hoses or steering box.

The hoses coming off the steering gear or touching, this was addressed as a problem in a TSB for the WJ. Not sure how this would cause the symptoms I’m experiencing.

Any other potential causes or fixes for this problem? Last resort would be to go back to the stock XJ high pressure fitting with the smaller hole and see if that fixes the problem, but I don’t really want to do this because I’ll lose my improved steering power. There is a cooler in the system using 3/8” hose on the return line.

I think you want to use the 1/2" return. It sounds to me like the pump is starving. If you increase possible flow (drilling the fitting) you need to be sure you can supply it. Maybe the cooler in the return circuit is slowing things down more than other installs? Dunno.
It's not necessarily the case that you have air being introduced. Pump starvation = foaming just on it's own. It sucks the air in & aerates the feed line, which becomes the return & voila the reservoir is foamed.

The cooler is plumbed properly?
Having them oriented wrong can trap a bubble in the system

There was a thread someplace on here that said that it wasn't the size of the fitting that caused the cavitation when using the smaller return, but the way the returns are setup inside the reservoir is different so that is why you have to use the larger return.

I am using the large return and while I'm pretty sure that I still need to replace my steering box, my WJ pump with cooler runs nice and quiet (I went to 1/2" line right shortly after exiting the steering box, then to the cooler and back to the pump).

donthelegend said:

I am using the large return and while I'm pretty sure that I still need to replace my steering box, my WJ pump with cooler runs nice and quiet (I went to 1/2" line right shortly after exiting the steering box, then to the cooler and back to the pump).

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Good info, thanks. So I have a path forward, but how do you connect .5" hose to the metal tube on the return line fitting coming out of the steering box? I'll also have to swap out the .375" hose barbs on my cooler for .5".

Definitely use the bottom (large) connector. I fought the same problem. Switching over fixed everything.

Lurch said:

Good info, thanks. So I have a path forward, but how do you connect .5" hose to the metal tube on the return line fitting coming out of the steering box? I'll also have to swap out the .375" hose barbs on my cooler for .5".

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I took my fitting to my local hose place and they brazed a hose barb on it.

I made an adapter with threaded hose barbs, 3/8 barb x 3/8 Npt female on one side and 1/2 barb x 3/8 npt male on the other.

I think you can also get adapters that are all one piece with hose barbs on either side but I couldn't find any locally.

Edit: too clarify, I left a section of the 3/8 hose on the metal tube that exits the steering box and put my hose barb adapter into that.

Re: Re: WJ Steering Pump - loud and frothy

old_man said:

I took my fitting to my local hose place and they brazed a hose barb on it.

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That sounds like a much better/cleaner solution than what I did.

Cool, I plan on using a Earl's AN tubing adapter that uses a compression fitting to connect to the power steering hard line. That's what I used for my transmission lines and I've been happy with the performance.

I'll report back once I get the fittings installed to see if this fixes the problem.

The return hose will work fine, but remember that the high pressure side can go up to 4000 psi. For that you pretty much need very high pressure hydraulic hose with swaged connectors

Scott was it an 04 WJ V8 pump? Those require a special fluid because of the hydraulic fan clutch. Just a thought man.

This was what I had to do to get the pump to work with a bored out XJ fitting on the high pressure line matching the diameter of the WJ one. I originally didn't do this and felt little difference in power with the WJ pump using the unmodified XJ fitting. After enlarging the difference in power is night and day. I’m running 33” KM2 tires.

The problem I was having is the fluid was cavitating because the flow on the return line was restricted. This was causing the fluid in the reservoir to become very aerated and the pump would whine whenever throttle was applied or I would turn the wheels.

Parts list:

Power steering pump off of a '99-'04 4.7L Jeep Grand Cherokee
Derale single pass heat sink cooler p/n 13250
Length of .5" ID transmission oil hose

The following fittings from Earl's AN Plumbing were used:
984008 x2 - push-on fittings for the cooler
165086 x1 - tube adapter for return line coming out of the steering gear*
700109 x1 - push-on fitting for the tube adapter

*you can get fancy and get an adapter fitting that will thread directly into the steering gear return port, but the largest output size I could find was -6 which is the same diameter as the existing hard line and wouldn’t let me hook up to a .5” hose so I used a tubing adapter to a -8 push on fitting.

The key to making this work for me was to use the bottom .5" return port on the WJ pump instead of the .375" one on the side. I was also using a dual pass cooler with .25" NPT fittings which I'm guessing was restricting flow as well. I switched to a single pass cooler with .375" NPT fittings in order to use .5" hose. Results are good, still have increased steering power and the pump is quite.

Pics of the setup:

Sorry to dig up an older thread, but this is the closest situation to what I am dealing with.

I have the WJ pump swapped in, I bored out the XJ pressure fitting and am using the 1/2 inch return, however I have no cooler plumbed in.

Short little trips to the store and back are no problem but when I need to go across town I start to cavitate and end up blowing steering fluid everywhere.

Lurch I know you must have done quite a bit of research on the WJ pump... is a cooler necessary? It seems like the reason I keep blowing might be because the pump is starving possibly? I don't know where to go on this.

Following. I did the pump and haven't bored out the fitting yet.

Now in my research on this upgrade I found this thread that touched on the whining pump after boring out the fitting. Now if you scroll down to post #7 there is a guy who talks about how he bored it but not to match the same size as the WJ fitting. He drills it out to only 3/16"and says thats enough to increase flow but not so much that the pump cavitates. Worth giving a try first since its far less work to do that and if it doesn't work for you, you can always drill it out the rest of the way and do all the other work mentioned above.

http://www.jeepforum.com/forum/f9/wj-grand-cherokee-power-steering-pump-swap-1167530/

Ben824 said:

Following. I did the pump and haven't bored out the fitting yet.

http://www.jeepforum.com/forum/f9/wj-grand-cherokee-power-steering-pump-swap-1167530/

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Sweet thanks man maybe ill grab another xj pressure fitting and swap it in.

So I'm pretty sure I fixed the problem... thanks Ben. It turns out I followed the wrong advice and drilled the xj pressure fitting to the same as the WJ fitting... wayyy too big. I ended up drilling a new fitting out to 5/32 and it seems like its already way better. Not as easy of steering as what it was before haha but also not cavitating.

VIEWFINDER said:

So I'm pretty sure I fixed the problem... thanks Ben. It turns out I followed the wrong advice and drilled the xj pressure fitting to the same as the WJ fitting... wayyy too big. I ended up drilling a new fitting out to 5/32 and it seems like its already way better. Not as easy of steering as what it was before haha but also not cavitating.

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Glad that worked! So its not as much power over drilling out to the WJ size, but is it still a fairly significant improvement over the stock XJ pump?

And I will say the WJ size isn't necessarily wrong advice, there is just more that needs to be done to make that work. Remember the WJ pump is supposed to be running the power steering under the heavy weight of the WJ with a V8 but also it is running the hydraulic cooling fan for the radiator. So that pump has a lot of work to do on a WJ so it not only needs to be powerful but also to move a lot of volume to a lot of places. Well since the XJ lines are smaller than the WJ lines and the amount of places it needs to go is far less, the pump cavities because the fluid just can't move around that quick in such a short trip and small space, if that makes sense. Now with the addition of the cooler like the examples above and going to the bigger return lines, the fluid has more space to fill and slow down on its way back to the pump. Thus solving the problem of the pump cavitating. Atleast thats what my redneck engineering degree has come up with haha

So I've been poring over this for a week, and have yet to find any info actually stating the WJ pump is actually stronger than the XJ pump. In all the info I've dug up the TC pump used on Jeeps is rated at 2.4 - 2.8 gpm and 1350-1450 psi, and I can find no other info stating more, or less performance except on aftermarket "high performance" pumps. Has anyone actually confirmed, or found actual numbers stating the WJ pump is stronger than the XJ pump? Also from what I'm understanding the "high pressure" fitting as everyone is calling it is actually the flow control valve which controls the flow, aND pressure of the pump. Now if the way I understand all of this there is actually no difference between the pump used on an XJ v/s the pump used on the V8 WJ aside from a different tank, and different flow control valve. Anyone care to speculate?

In my experience, most ps pumps only but out 1200-1400 psi, as read by my gauge set at work. I highly doubt the wj puts out more than an xj, since most components are designed around this pressure. It may have slightly higher volume since some had that hydraulic fan, but it would be unnecessary for a stock system. Usually Everytime I hear this, someone had a failing pump and replaced with a wj pump and claims how much better it is. So hard to truly say.