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Transmission Cooling

Here's what you need to know:


  • Most recommended radiator to install:   3 Row Copper / Brass Radiator
  • Cons about Plastic tanks
    • They don't cool as quickly as copper/brass
    • over time they become brittle


Engine Cooling System

Questions about the engine cooling system?  

General Cooling System Info

 There are 2 types of Cooling systems on the XJ/MJ

  1. Open style - any normal cooling system used today.
  2. 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.


Troubleshooting Cooling System

XJ's tend to have issues overheating.    XJs changed from Closed to Open Cooling systems in 1990.  

Here are some troubleshooting steps to determine the cause.

Check for Air in the system

Sometimes if you overheat, have a bad radiator cap or general leak, you can get air in the system.     The easiest way to eliminate all air is to have a Tefba Coolant filter mounted at the highest point of the radiator hose.    The Tefba Coolant filter provides an easy entry to fill the cooling system and burps air since its at the highest point.

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