Questions about the engine cooling system?
General Cooling System Info
There are 2 types of Cooling systems on the XJ/MJ
- Open style - any normal cooling system used today.
- Closed style - no radiator cap and utilizes a pressure bottle. used in 87-90 XJs.
- Change engine coolant every 12,500 miles or 12 months.
- Thereafter change engine coolant at the beginning of every winter season.
- Maintain ethylene glycol and water solution at a mixture of 50/50.
Cooling System Specs
Temp F (C)
|2.5L||192-198 (89-92)||12-15||10 (9.4)|
|4.0L||192-198 (89-92)||12-15||12 (11.3)|
|4.2L||192-198 (89-92)||12-15||10.5 (9.9)|
(1) - Without A/C 23 qts. (2.1L) for recovery tank.
(2) - Includes 1 qt. (.9L) for recovery tank.
Coolant Temperature Sensors
- the 99 XJ has only 1 coolant temp sensor which is located on the Thermostat Housing
Cooling System Upgrades and Tech Write-ups
- Replacing the Mechanical Fan with another OEM Aux Fan - External Write-up on NAXJA
- Replacing the Mechanical Fan with an Electric Aftermarket Fan - Writeup by Marcus
- Installing Dirtbound Offroad's 3 electric fan XJ kit