Mishimoto MMRT-JL-18 Aluminum Coolant Expansion Tank for 2018-2026 Jeep Wrangler

Vehicle Fitment

• 2018-2026 Jeep Wrangler JL (Sport, Sport S, Willys Sport, Willys, Sahara, Sahara Altitude, High Altitude, Rubicon, 4xe - 2.0L I4 Turbo / 3.6L V6 Pentastar / 3.0L EcoDiesel V6, 4WD)
• 2020-2026 Jeep Gladiator JT (Sport, Sport S, Willys, Mojave, Rubicon, Overland - 2.0L I4 Turbo / 3.6L V6 Pentastar / 3.0L EcoDiesel V6, 4WD)

Fitment Notes

• Does NOT fit the Jeep Wrangler JL Rubicon 392 equipped with the 6.4L HEMI V8 - the 392 uses a different expansion tank configuration.
• Fits all other Wrangler JL trims and all Gladiator JT trims across all supported engine options (2.0L, 3.6L, 3.0L EcoDiesel).
• Compatible with both the factory Jeep radiator cap and the included Mishimoto high-pressure radiator cap.
• The worm gear clamp included in the kit secures the coolant hose connection to the tank - do not reuse the OEM clamp.

Features

• TIG-welded aluminum construction permanently eliminates the seam cracking and coolant leaks common in the stock plastic expansion tank.
• Internal OEM-style baffling prevents coolant aeration and fluid slosh when the Jeep is off-camber, articulating, or moving through rough terrain.
• Integrated sight glass replaces the factory dipstick for fast, accurate coolant level checks without removing any components.
• Wrinkle black powder-coated finish provides long-term corrosion resistance and an aggressive under-hood appearance that suits the JL/JT platform.
• Increased fluid capacity over the factory plastic tank provides a greater coolant reserve during towing, trail use, and sustained off-road driving.
• Direct-fit design - installs without cutting, modification, or special tools.
• Backed by Mishimoto's Lifetime Warranty.

Specifications

• Fitment: 2018-2026 Jeep Wrangler JL / 2020-2026 Jeep Gladiator JT (excl. Rubicon 392 / 6.4L)
• Material: TIG-Welded Aluminum
• Finish: Wrinkle Black Powder Coat
• Baffling: Internal OEM-Style Anti-Slosh Baffling
• Fluid Level Indicator: Integrated Sight Glass
• Capacity: Increased vs. OEM plastic tank
• Radiator Cap Compatibility: OEM Jeep and Mishimoto
• Installation Difficulty: Easy

Included Components

• 1x Mishimoto Aluminum Coolant Expansion Tank (Wrinkle Black)
• 1x Worm Gear Clamp
• 1x O-Ring
• 1x Mishimoto Radiator Cap
• 1x Mishimoto Lifetime Warranty

Product Description

The Mishimoto MMRT-JL-18 is a direct-fit aluminum coolant expansion tank engineered specifically for the 2018-2026 Jeep Wrangler JL and 2020-2026 Gladiator JT. The factory plastic expansion tank on both platforms is a well-documented failure point - thin-wall plastic construction is inherently vulnerable to seam cracking after repeated heat cycles, and even a small crack can escalate from a minor drip to a full coolant loss situation on the trail or during a tow. Mishimoto's TIG-welded aluminum replacement eliminates this failure mode entirely, delivering a tank designed to outlast the Jeep itself.

Two design features set this tank apart for off-road use specifically. Internal OEM-style baffling keeps coolant from aerating or sloshing when the Wrangler or Gladiator is at severe angles - a condition that can introduce air into the system and cause inconsistent cooling system pressure in trail environments. An integrated sight glass replaces the factory dipstick, allowing a quick visual coolant level check at a glance without removing the cap or digging for the dipstick. The wrinkle black powder-coated finish adds corrosion resistance and pairs naturally with the rugged aesthetic of both platforms' engine bays.

Installation is rated easy and can be completed before a weekend trip - the kit ships with a worm gear clamp, O-ring, and Mishimoto high-pressure radiator cap, covering everything needed for the swap. Note that this tank does not fit the Rubicon 392 (6.4L HEMI V8) variant of the Wrangler JL, which uses a different cooling system layout. All other JL and JT trims across the 2.0L, 3.6L, and 3.0L EcoDiesel engines are fully supported. Backed by Mishimoto's Lifetime Warranty.