A Bad Thermostat in a 1995 Montero

The Montero hit the U.S. market for the 2003 model year, but its overseas version, known as the Pajerno, gained all the glory by winning the Paris-Dakar rally in 1983. The Montero, however, garnered the attention of off-road enthusiasts in the United States thanks to its rugged and simple nature. As time progressed, Mitsubishi began adding some refinement to the rugged Montero. By 1995, the Montero came standard with features that were high-end for its era, including air conditioning, power windows, cruise control and a six-speaker AM-FM-cassette stereo system. A relatively powerful 177-horsepower, 3.0-liter V-6 was also standard on the 1995 Montero LS and a 214-horsepower, 3.5-liter V-6 came standard in the 1995 Montero SR. Replacing the thermostat on both engines is a similar straightforward task that can save you money.

Instructions

1

Allow the vehicle to sit until the engine is cool to the touch. If you recently drove the Montero until it reached operating temperature, it may take several hours to cool.

2

Raise the front of the Montero with a floor jack and slide jack stands under the SUVs frame rails. Lower the vehicle onto the jack stands.

3

Crawl beneath the radiator and find the drain plug a small thumbscrew on the bottom of it. Position a drain pan under the drain plug and remove the drain plug by unscrewing it from the radiator. Allow all of the coolant to drain from the radiator and into the drain pan.

4

Inspect the O-ring on the end of the drain plug for brittleness, looseness or cranks. If any of the listed defects exist, replace the drain plug with a new one. Tighten the drain plug into the bottom of the radiator.

5

Raise the Montero off the jack stands with a floor jack and remove the jack stands. Lower the SUV to the ground.

6

Trace the upper radiator hose on the 3.0-liter engine or the lower radiator hose on the 3.5-liter engine toward the engine until you meet the metal housing connecting the hose to the engine -- this is the thermostat housing. Remove the two bolts securing the thermostat housing, using a ratchet and socket.

7

Pull the thermostat housing from the engine, with the radiator hose attached, and pull the thermostat from the engine. Pull the gasket from the thermostat housing-to-engine mating surface. Scrape the mating surface on the engine and thermostat housing, using a plastic gasket scraper.

8

Insert the thermostat into the engine, spring side first. Set a new thermostat gasket on the engines mating surface and align the bolt holes on the gasket with those in the engine. Set the thermostat housing on the engine and hand-thread its bolts. Tighten the thermostat housing bolts to between 12 and 14 foot-pounds on the 3.0-liter engine or 17 foot-pounds on the 3.5-liter engine, using a torque wrench and socket.

9

Find the bleeder valve on top of the thermostat housing and open it by removing the bolt at the center of it. Open the radiator cap and fill the radiator slowly with 50-50 premixed ethylene-glycol-based (green) coolant until the coolant bubbles out of the bleeder valve. Thread the bleeder valve bolt into the bleeder valve then tighten it to between 9 and 15 foot-pounds with a torque wrench and socket.

10

Add more coolant to the radiator until it reaches the bottom of the radiator fill neck, if needed.

11

Start the engine and allow it to idle. Watch the coolant level in the radiator and refill the radiator each time the level drops. Once the upper radiator hose feels hot, verify that the coolant level is at the base of the filler neck and refill it with 50-50 premixed coolant, if needed.

12

Reinstall the radiator cap and shut the engine off. Allow the vehicle to sit until the engine is cool to the touch. Check that the coolant level is between the Low and Full marks on the coolant overflow tank. Pull the cap on the coolant overflow tank upward to open the tank and add 50-50 premixed coolant, as needed. The total coolant capacity of the 3.0-liters cooling system is 2.5 gallons, but the amount needed to refill your Montero will vary.

13

Take the old coolant to a local used automotive fluid recycling center for disposal. Some auto parts stores take old coolant free of charge.