|Cooling System Upgrades
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Is your Jeep 4.0 engine getting hot under the collar?
Heavy-duty 2-core radiator
The factory plastic 1-core radiator isn't up to the job of properly cooling the 4.0 engine in hot conditions. The factory 2-core heavy duty radiator fitted to vehicles with the optional towing package is much better, and it'll even keep a 4.6L stroker engine cool. The ultimate solution is to fit an aluminum heavy-duty 2-core radiator. It's available for both the closed ('87-'90) and open ('91-'00) cooling systems the Jeep Cherokee has used over the years. You need to specify the model, year, engine type and transmission type when ordering.
Flowkooler high-flow water pump/ Robertshaw thermostat
Flowkooler water pumps solve low-speed heating problems by doubling the water flow rate at low RPM and idle. At 3,500 RPM the flow rate returns to normal to prevent too much water flow at high speed.
Dual electric fan conversion
There are two problems with the stock clutch fan. The first is that when the engine is idling, the engine temperature reaches 220*F after a few minutes and the electric fan is triggered to switch on. Clearly the clutch fan isn't up to the job of keeping the engine cool enough by itself. The second is that when the clutch fan does engage, it makes a lot of noise and imposes a lot of drag on the engine (it weighs a hefty 5lb). This costs horsepower due to the engine driving the fan. Gas mileage is also reduced particularly in conditions where the clutch fan is most likely to engage i.e. city driving.
An easy way to remedy these problems is to replace the clutch fan with an electric fan. I have done this conversion with great success on my Jeep by mounting a 14" High Performance 1500-1800cfm electric fan to the stock clutch fan shroud. For more details, click on the image to the left or go to Dino's dual electric fan conversion.