Jeep Power Steering Cooler Installation

Starting off with the first featured project is my installation of a Power Steering Cooler on my Jeep. A little backstory on the Jeep, my parents bought it new in 1993 when the Grand Cherokee (ZJ) first came out. When new the only options on this Jeep were the V8 engine, towing package, skid plate/foglight group, and AM/FM Cassette. Grand Cherokees were fairly expensive back in the day, this one had an MSRP of $26,000!

I was the first person in my family to drive this Jeep, I was 15 and the Jeep had 8 miles on the odometer. Approximately 200,000 miles later the Jeep was given to me. Now that's a lot of miles but the Jeep was in decent condition cosmetically. Mechanically it needed some work so it'll be featured here for quite a few projects. Remember as I said in the first post, I am not an expert just a guy sharing his projects, if you want to try one of the projects go ahead at your own risk. I suggest you buy a service manual for your vehicle as they have a lot of good safety tips.

One of my first projects was to add a power steering cooler. Grand Cherokees delivered in Europe were originally equipped with coolers for the power steering system due to the different driving demands European roads. Your power steering system is under high levels of stress when operating in high temperatures and parking lot speeds. At the speeds we drive in the United States (45-75mph) the system is not being stressed nearly as much. I guess the bean counters at Chrysler decided the coolers would be unnecessary for us in the US.

The power steering pump is mounted to the engine and raises the pressure of the power steering fluid. This fluid is sent in a high pressure line to the power steering box, inside the steering box this high pressure fluid is used to assist the steering for the driver. Raising the pressure of any fluid consequently raises it's temperature. Raising the pressure repeatedly (like rock crawling or driving in parking lots) will eventually cause the fluid to overheat and break down. The fluid also heats up when the pump is run at a high rpm for long durations. During the break down of the fluid the lubricating properties are diminished and wear occurs in the components. The power steering box in Grand Cherokees is already somewhat undersized. Depending on the type of driving you do the box can be worn out at 70K miles.

The ideal situation is to upgrade your transmission cooler to a larger aftermarket unit and at the same time install the OEM cooler over on the power steering system. I just happened to come across the OEM cooler from a wrecked Jeep for a good price. Considering that a good transmission cooler kit will run anywhere from $50 to $100 and a new steering box is $200 it's just good insurance to install the cooler.

Because every car I've ever owned has been equipped with a power steering cooler and most of the power steering components on a Grand Cherokee are located within one foot of the driver's side exhaust manifold I decided to research the install. According to my local dealership a kit was offered when ZJs were new in the mid 90's. The dealer also said the OEM cooler setup is no longer available as a kit. The parts guy did say that it looks very similar to the auxiliary transmission cooler installed on Grand Cherokees with the factory tow package. With that information I bought a used transmission cooler with the bracket from a wrecked Jeep.

The removal of the front of a Jeep varies by year but for my 1993 model the first step was to remove the fog lights. The fog lights are mounted to a metal bracket and quite simple to remove by loosening the bolt and they come off. The harness connectors may be behind the grill so remove the six screws securing the grill to it’s support behind. With the grill removed you’ll be able to remove the headlights. The headlights are held in by two clips. One clip is at the inboard top corner and the other clip is at the outboard bottom corner. A firm tug will pop the headlights out, be careful not to break the clips. With the headlight loose disconnect the headlight from the harness. The corner lights and turn signals are held in with screws located between the housings. Yes some engineer thought it was a good idea to hide the screws and make you force the housings apart to get a screwdriver on the screws.

The bumper cover itself is held to it's support with a couple of screws across the top and a few screws in through the bottom. There are also push type fasteners in the wheel wells which need to be popped out and will probably be destroyed in the removal. My local hardware store had a selection of the plastic fasteners, I was able to locate some that would work as replacements. With the cover and support out of the way the front of your Jeep will look something like this.....

In this photo you can see the OEM transmission cooler mounted on the passenger side bracket. The empty bracket is where the power steering cooler will be mounted.

Now that the front of your Jeep is bare you can test mount your power steering cooler. I found that the bracket from the wrecked '97 Grand Cherokee would not fit my '93 model. In 1996 Jeep made slight changes to the front of the Grand Cherokee model, rather than modify the new bracket I just reused my original one. This photo shows the newer bracket, I later decided to use the original 1993 bracket.


The next task is to route your hoses from the power steering box to the cooler and finally return to the power steering pump. First remove the airbox for the engine to allow access to your lines and the pump. The high pressure fluid exits the power steering pump and goes down into the steering box. The fluid returns to the power steering pump through a regular fluid hose to the reservoir. This is the line we are going to intercept with the cooler. We want to take that hot fluid out of the steering box and cool it down before it goes into the pump.

This photo sequence identifies the hoses and shows which one to cut. An important point about the power steering reservoir, it is made of plastic. Because of that it is very easy to break the inlet nipple off of the reservoir, most likely meaning you'll need to buy a new pump or get really good with super glue. To avoid that mistake first cut the hose in the middle and then slice it down the middle after removing the clamp. You won't be applying any force to the reservoir and save the neighbor kids from learning new words.

Here's the shot showing the return line cut in the middle. If you accidentally cut the high pressure line it is only a $15 part, it's really not a bad idea to replace it any way. When that high pressure line starts to leak it has a tendency to spray on the exhaust manifold and possibly cause a fire.

Make sure when buying your hose that you buy about four feet of high pressure transmission return line. Do not try using heater hose in this application. Your cooling system operates at a maximum of 15psi, the return line on your power steering system can see pressures more than 10 times that amount. The line is not cheap but you don't want to skimp on something so close to the exhaust manifold.

The new return line will go from the power steering gear box to the inlet of the transmission cooler. I connected this line to the bottom nipple on the power steering cooler and ran the return line from the top of the power steering cooler back to the pump. As you can see in the photo I used rubber line entirely, I may fabricate some metal lines for the section that passes through the radiator support. There is a possibility of abrasion in this area and I don't want to lose all of my fluid due to a leak.

The power steering system will need to be bled after this installation. The procedure for bleeding the power steering system is to fill the reservoir and rotate the power steering pump (it will obviously be much easier to accomplish rotating the pump if you remove the serpentine belt). Your really don't want to rotate the pump by starting the engine until you have plenty of fluid in the system. As you rotate the pump by hand you will see air bubbles popping up through the fluid in the reservoir. With the cooler you have added fluid capacity to your power steering system so it will take a bit more fluid. Once you are no longer seeing bubbles get inside the Jeep and turn the steering wheel back and forth from stop to stop 40 times with the front wheels in the air. Yes 40 times! If you do not get all of the air out of the steering system you may end up with a noisy power steering pump. Top off the fluid to the COLD mark and start the Jeep. Make sure you keep the reservoir at the COLD level.

Your system should be topped off and running a lot cooler! Periodically check the fluid level and check for leaks.