The thermostat is a regulating device that’s vital to the proper cooling and operation of your Honda Passport. When your 6VD1 3.2 liter Honda truck engine warms up to the proper operating temperature, the thermostat opens allowing the coolant to pass into the radiator. When your thermostat or the wax pellet that determines the operating temperature becomes worn or damaged, your Honda thermostat could fail or stick closed or open.
Such a condition could trip several warning OBDII trouble codes, from P0171 to P0174 as your Honda Passport ECU struggles to maintain the right temperature. Such fluctuations will move the ECU from it’s normal operating temp fuel maps, because your thermostat isn’t working right, this can lead to lean or rich conditions.
Today I’ll be showing you how to replace a Honda Passport thermostat in a 3.2 liter 6VD1 engine. The part number for this replacement thermostat is 89712-31614 and you will also need the replacement thermostat o-ring or gasket which is part number 89712-31620.
Before you begin our how to replace a Honda Passport thermostat DIY Guide, you would be best served by disconnecting your negative terminal on your battery and draining your radiator.
Make sure you properly dispose of your old coolant, and you follow the safety guidelines for working on your vehicle. If you aren’t sure how to be safe while working on your own car, check our list of tips here.
After you’ve allowed your Honda Passport radiator to drain, you can disconnect the lower radiator hose. This lower Passport radiator hose connects to the thermostat housing and water neck, which holds your factory thermostat.
Using a 10mm open ended wrench, carefully loosen and undo all three 10mm bolts that hold the thermostat housing on the engine. You may or may not have a hard time getting to that lower 10mm bolt.
If your bottom 10mm bolt is giving you problems, remove the top two first as shown above. Carefully pull off the thermostat, making sure you aren’t damaging the threads or the bolts.
After you’ve removed the old thermostat housing, pull off your old thermostat and thermostat grommet.
Make sure to carefully remove your old Honda Passport thermostat gasket, so you don’t scratch or etch the aluminum back half of your water pump.
Remove old thermostat gasket and prep your new thermostat and thermostat gasket for installation into your Honda Passport.
After cleaning and drying the back half of your Honda Passport water pump, you are ready to insert your new thermostat.
Apply a light film of high temp RTV gasket maker to the thermostat housing before install.
Again the lower 10mm bolt on your thermostat housing may prove difficult. If so, install this bolt first so that you can easily rotate the rest of your thermostat housing in place. Secure and tighten the 10mm bolts to specification, and allow for 2-3 hours as your RTV gasket maker cures and dries.
Once your thermostat housing is installed and gasket dry, reconnect the radiator and fill with coolant. Start your Honda Passport to complete our how to replace a Honda Passport thermostat DIY article, and make sure that the vehicle does not overheat.
Honda Passport thermostat part number 89712-31614 opens at 170º Fahrenheit, you will need to check for temperature and that your coolant fans turn on. Do not attempt to drive your Honda Passport until you are done replacing the thermostat, and you are sure there are no leaks and zero issues with overheating.
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