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 time or another. The inline 4.0L six-cylinder engine has a good reputation for being reliable and lasting more than 200,000 miles, but it can also get hot when you crawl rocks, pull heavy loads or drive up a steep, long hill in hot weather. weather conditions.

Over the decades, terrain enthusiasts have found many solutions to their XJ Cherokee cooling problems, but some have not always identified the root causes. The most common problems arise from cracked or worn hoses, a fixed thermostat, a bad fan connection or a worn water pump. But when all these things work as they should and the engine still overheats, other factors come into play. Rock creep or a worn engine 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 at extreme rock creep, which causes the radiator to crack and leak over time. According to Matt Dawson at Champion Cooling Systems, Jeep XJ owners call and complain that their relatively new coolers are leaking just like the old ones they replaced. “It’s a regular call we get from Jeep Cherokee owners crawling,” says Dawson. “Those jeeps without frame stiffeners or twisting in the roll cage are enough to add stress to the factory coolers, and over time the coolers will crack and leak,” he said. “We have heard of cases where the factory’s plastic tanks have been opened by the stresses and left the jeep owner stranded.”

Jeep XJ Cherokee cooling problems may be related to something else

Similarly, a broken engine mount does not 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 which started to have excessive cooling problems that we could not figure out.

The cooling system in our XJ worked correctly, without leaks and with a relatively new thermostat and water pump. Under normal conditions, the engine would get hot but not overheat under heavy load or when traveling up long highway slopes at 90F + degree days. This was a condition we lived with for a long time until we began to notice that this summer the engine temperatures would approach boiling point (about 260 degrees) from short trips around town.

A hard-worn engine mount allowed the fan clutch to move into the radiator.

Our first thought was that the fan clutch was starting to get bad, so we first chose a very popular upgrade among XJ owners, which involves replacing the factory fan clutch with a powerful unit from a Jeep Grand Cherokee. By using the larger fan coupling (Haden # 2796), the fan stays connected 100 percent longer, which provides more air flow at low engine speeds. On a factory system, this works extremely well, except that some XJ owners do not like the rushing sound of air that it gives. In reality, it is the same sound as the factory fan, it just lasts longer.

The factory clutch on the left does not stay connected 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 did provide some improvement, it did not cure the overall problem. With our engine running high, our next thought was that the factory’s radiator was clogged and less coolant was flowing through it. We chose to install a larger radiator. A factory replacement would have been the cheapest option, but we thought that if this were the problem it would not make any significant improvement. Instead, we chose to go with a larger radiator made entirely of aluminum from Champion Cooling Systems.

Champions radiator completely in aluminum is a rod and pipe 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’s copper core and plastic tanks. We used Champions # BC1193 for XJ Cherokee, which has the same width and height as the factory cooler but has a thicker core.

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

For XJ owners, this means less strain on the radiator during rock crawling and more surface for the heat to be dissipated. In addition, Dawson pointed out that the heat sinks on their radiators have slats to improve airflow and heat dissipation. The radiator comes from Champion ready to install and has factory fittings for the transmission radiator.

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 auxiliary electric fan from the factory. Once we pulled on the radiator, we noticed the damage from the fan connection. While the new Grand Cherokee clutch is installed much closer to the radiator, there were approximately 1/2-inch gaps. At some point, the factory connection had been pushed into the radiator, which caused the fins to close tightly, but not enough to leak.

The engine movement was the result of a worn engine mount. The rubber on one side of the bracket had broken and exposed the center bolt sleeve. It allowed the engine to move when loaded but remained during normal operation. We replaced the brackets and started installing the Champion radiator.

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

When we realized that by installing this radiator, there is not enough space for even the original factory connection fan unit, we chose the Champion fan and shield kit for this particular radiator. The kit consists of an aluminum housing, three 10-inch high-capacity S-blade fans and includes cables, temperature sensor, relays and wiring connections. We also chose to change the fan wires to waterproof contacts for our own peace of mind, and to use a relay for each fan to avoid overload when they start.

The Champion cooler fits perfectly on the factory site by reusing factory brackets and bolts. Since the radiator is slightly thicker, we had to grind away a few tabs from the radiator core, so that it would fit over the radiator and provide enough space for the latches for the hood 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 cover. This slipped into place and noted that in some cases the factory’s A / C condenser lines may need to be pushed away 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 be turned 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 T-coupling in brass 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 space between the factory and Champion sensors.

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

When the fans are connected and installed, they turn on at 190 degrees and keep the engine extremely cool. With A / C on during a 90-degree day and driving the XJ uphill, the temperature never exceeded 210 degrees on our factory instrument meter. At idle 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 flowed through the radiator, the temperature would fall 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 do not have to look at the temperature gauge all the time while driving allows XJ owners to enjoy their vehicles much more than they already are.

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