Overview
The Mishimoto MMTS-WRA-03L is a 180 degree racing thermostat for 2.4L 4-cylinder and 3.8L 6-cylinder engines, fitting Jeep Wrangler TJ, LJ and JK models from 2003 to 2011. It is a direct fit for two and four-door models.
The low-temperature racing thermostat opens at 180 degrees F (82 degrees C), compared with 195 F (90.5 C) for standard units. Opening sooner once the engine is warm lets coolant reach the engine earlier, and running cooler helps reduce engine wear and improve reliability.
It suits highway cruising and climbing over boulders, where an effective cooling system matters. Each unit includes the Mishimoto Lifetime Warranty.
Key features
- Opens at 180 degrees F (82 degrees C) instead of the standard 195 F (90.5 C)
- Low activation temperature allows coolant to flow through the engine sooner once warm
- Designed for 2 and 4-door Wrangler models
- Suited to 2.4L 4-cylinder and 3.8L 6-cylinder engines
- Direct fit design
- Includes the Mishimoto Lifetime Warranty
Cooling for trail and highway
A racing thermostat changes the timing of coolant flow rather than the total cooling capacity. On a Wrangler that alternates between highway speeds and slow crawling, that timing matters: the engine can reach operating temperature sooner and stay there with less cycling. The trade-off is that very cold weather may keep the gauge lower than drivers expect.
Before you install one, check the radiator, fan, coolant level and radiator cap. A lower-opening thermostat helps, but it cannot make up for a clogged radiator or a worn water pump. Trail rigs that see steep climbs and long idles in heat benefit most from a complete cooling check, not just a new thermostat.
When replacing the thermostat, clean the housing seat, install it with the spring facing the engine, and use the correct coolant mix. Bleed air from the system and watch the gauge on the first few drives. Recheck the coolant level after the engine has cooled to be sure no air pocket remains.
Specifications
| Brand | Mishimoto |
|---|---|
| Part number | MMTS-WRA-03L |
| UPC | 748666008021 |
| Type | Racing thermostat |
| Temperature rating | 180 degrees F (82 degrees C) |
| Standard thermostat opening | 195 F (90.5 C), as listed |
| Engines | 2.4L 4-cylinder and 3.8L 6-cylinder |
| Body styles | 2 and 4-door models |
| Fitment type | Direct fit |
| Warranty | Mishimoto Lifetime Warranty |
Vehicle fitment
The manufacturer fitment list for this thermostat covers three Jeep Wrangler generations: 2003-2006 Wrangler (TJ), 2004-2006 Wrangler (LJ) and 2007-2011 Wrangler (JK). Listed trims across these generations include Rubicon, Sahara, Sport and X, along with Unlimited, Unlimited Rubicon, Unlimited Sahara, Unlimited X and several anniversary and edition versions.
The fit covers 2003 to 2011 TJ, LJ and JK models. JK models from 2012 onward, plus JL, YJ and CJ models, fall outside this fit. Confirm your vehicle’s year, model and trim before ordering.
What’s included
The thermostat and the Mishimoto Lifetime Warranty are included. Check the package contents against your installation before starting, including any gasket or hardware you may need.
