Wrangler JK Coolant Flush

The Jeep Wrangler I purchased needed some preventive maintenance.  The coolant in the recovery bottle looked dirty, and there were no records of it being changed.  I also noticed that the heater didn’t get that hot.  Good maintenance is especially important on an off-road vehicle so it seemed like a good time to get the caught up. 

Jeep Wrangler JK Coolant Drain
Coolant drain in red.  Located on the passenger side bottom of radiator.  



I started by draining the coolant out through the drain valve at the bottom of the radiator.  Next, I drained the coolant recovery bottle.  Once the coolant stopped dripping into the drain pan, I filled the system with distilled water, ran it and drained that as well. 

Zerex G05

Research indicates that its common for the Jeep Wrangler heater core to get plugged up, so I gently flushed it both directions with compressed air and distilled water.  A lot of crud came out. 

Finally, I refilled the cooling system with a 50:50 mix of Zerex G05 coolant using a Lisle Spill Free Funnel.  The funnel raises the level of coolant above the radiator, this aids in getting the air out of the system.  A note on the Zerex G05, it is almost clear and has a lot less color than factory.  I replaced the radiator cap with a Gates# 31525 (which was Motorad brand in a Gates box).  

Zerex G05 is the specified coolant for the JK Wranglers with the 3.8 only.  If you have a 3.6 DO NOT USE this coolant. 

Parts Needed
  • Radiator Cap - Gates# 31525
  • Coolant - Zerex G05

The cooling system took roughly 3 gallons of coolant. 

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