Jeep XJ Cherokee Cooling Problems and Remedies

Anyone who has ever owned a Jeep Cherokee XJ has had to deal with engine cooling problems at one point or another. The inline 4.0L six-cylinder engine has a solid reputation for reliability, lasting more than 200,000 miles, but it can also get hot when crawling rocks, hauling heavy loads, or driving up a steep, long hill in hot weather. weather conditions.

Over the decades, off-road enthusiasts have found many solutions to their XJ Cherokee cooling problems, but some have not always determined the root causes. The most common problems arise from cracked or worn hoses, a stuck thermostat, a bad fan clutch or a worn water pump. But when all these things are working properly, and the engine still overheats, other factors come into play. Rock creep or a worn motor mount are not usually seen as causes of poor cooling, but they are often the problems that can lead to persistent overheating.

Extreme rock crawling can twist the XJ’s unibody and cause radiator leaks.

Because the Jeep XJ has a unibody and no steel frame, it twists during extreme rock crawling, causing the radiator to crack and leak over time. According to Matt Dawson at Champion Cooling Systems, Jeep XJ owners are calling and complaining that their relatively new radiators are leaking just like the old ones they replaced. “It’s a common call we get from Jeep Cherokee owners that crawl,” says Dawson. “Those Jeeps without frame stiffeners or torsion in the roll cage enough to add stress over the factory radiator core, and over time the radiators will crack and leak,” he said. “We have heard of cases where the factory plastic tanks have been opened by the strain, leaving the Jeep owner stranded.”

Jeep XJ Cherokee Cooling problems may be related to something else

Likewise, a broken engine mount doesn’t sound like a related cooling problem, but on Jeep XJs, a worn engine mount can go unnoticed for a long time until they cause a crack in the factory exhaust manifold, or if it allows the engine to move so much that it forces the factory fan clutch into the radiator under load. This was the case with our 1995 Jeep XJ that started having excessive cooling problems that we couldn’t figure out.

The cooling system in our XJ worked properly, with no leaks and with a relatively new thermostat and water pump. Under normal conditions the engine would get warm but not overheat under heavy load or traveling up long highway hills on 90F+ degree days. This was a condition we lived with for a long time until we started noticing that this summer the engine temperatures would approach the boiling point (about 260 degrees) from short trips around town.

A severely worn motor mount allowed the fan clutch to move into the radiator.

Our first thought was that the fan clutch was starting to go bad, so we first opted for a very popular upgrade among XJ owners, which involves replacing the factory fan clutch with a heavy-duty unit from a Jeep Grand Cherokee. By using the larger fan clutch (Haden #2796), the fan stays engaged at 100 percent longer, providing more airflow at low engine speeds. On a factory system this works extremely well, except that some XJ owners don’t like the rushing sound of air it makes. In reality it’s the same sound as the factory fan, it just lasts longer.

The factory clutch on the left does not stay engaged as long as the new one from a Grand Cherokee on the right.

When it comes to Jeep XJ Cherokee cooling solutions, bigger is better!

Although it provided some improvement, it did not cure the overall problem. With our high mileage engine, our next thought was that the factory radiator was clogged and flowing less coolant through it. We chose to install a larger radiator. A factory replacement would have been the cheapest option, but we thought if this was the problem it wouldn’t make a significant improvement. Instead, we chose to go with a larger all-aluminum radiator from Champion Cooling Systems.

Champion’s all-aluminum radiator is a rod and tube design, which is stronger and has a thicker core.

The aluminum core and side tanks on the Champion radiator would provide higher heat dissipation over the factory copper core and plastic tanks. We used Champions #BC1193 for the XJ Cherokee, which is the same width and height as the factory radiator but has a thicker core.

According to Champion Cooling’s Matt Dawson, this radiator is a bar and tube design, as opposed to the traditional radiator tube and fin design. “The bar and plate design cooler is much like an intercooler, where each tube, flat plate and fins are stacked together and folded as a core and then welded to tanks,” Dawson said. “This eliminates the need for a header. In a rod and plate design, the header is removed to eliminate one less piece that can fail. There’s no expansion in the radiator, and it’s much stronger and more efficient at dissipating heat.”

For XJ owners, this means less strain on the radiator when rock crawling and more surface area for heat to dissipate. Additionally, Dawson pointed out that the heat sinks on their coolers have fins to improve airflow and heat dissipation. The cooler comes from Champion ready to install and has factory fittings for the transmission cooler.

Look at the big picture when it comes to XJ Cherokee Cooling

We started by removing the Grand Cherokee clutch and factory fan, as well as the factory electric auxiliary fan. Once we pulled the radiator we noticed the damage from the fan clutch. While the new Grand Cherokee clutch installs much closer to the radiator, there was about a 1/2-inch gap. At some point the factory fitting had been pushed into the radiator, causing the fins to seal closed, but not enough to leak.

The engine movement was the result of a worn engine mount. The rubber on one side of the mount had disintegrated, exposing the center bolt sleeve. It allowed the engine to move when under load but remained during normal driving. We replaced the brackets and started installing the Champion radiator.

We used Champions’ kit of three fans with an aluminum housing, temperature sensor, wiring harness and relays.

When we realized that by installing this cooler, there is not enough room for even the original factory clutch fan assembly, we chose the Champion fan and shroud kit for this particular cooler. The kit consists of an aluminum housing, three high capacity 10-inch S-blade fans and includes cables, temperature sensor, relays and cable connectors. We also chose to change the fan wiring to waterproof connectors for our own peace of mind, as well as use a relay for each fan to avoid overloading when they start.

The Champion cooler fits perfectly in the factory location by reusing the factory brackets and bolts. Since the radiator is slightly thicker, we had to grind off some tabs from the radiator core so it would fit over the radiator and leave enough room for the hood latches to close properly. This may only be for 1990-1995 Jeep XJ models, as the radiator supports for later models are slightly different.

Changes may be required.

With the radiator installed and the hoses connected, we installed the fan and shroud. This slid into place, noting that in some cases the factory A/C condenser lines may need to be moved slightly to allow clearance over the electric fan on that side. Once installed, we connected the fans to their appropriate relays according to the instructions on the kit. The system also operates from a temperature sensor, which allows them to turn on after the coolant temperature reaches 190 degrees. To do this, we removed the factory temperature sensor on the thermostat housing and replaced it with a brass tee that has the same 3/8″ NPT threads, with one male and two female ends. We also used a 3/8” NPT male to female adapter to provide clearance between the factory and Champion sensors.

To mount the temperature sensor, we used a 3/8-inch NPT tee on the factory thermostat housing. We used a male to female adapter to mount the factory temperature sensor.

Once the fans are connected and installed, they turn on at 190 degrees and keep the engine extremely cool. With the A/C on during a 90-degree day and driving the XJ uphill, the temperature never exceeded 210 degrees on our factory gauge. Idling in traffic, the temperature crept up but consistently remained a hair above the 210-degree mark. As soon as we were moving again, and more air was flowing through the radiator, the temperature would drop below the 210 mark.

The upgrade to the Champion aluminum radiator and fan kit worked better than we expected and was well worth the effort. Knowing that you don’t have to look at the temperature gauge constantly at any moment while driving allows XJ owners to enjoy their vehicles much more than they already are.

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