NISSAN Pictures of how I changed the Thermostat on my 87-95 Nissan Pathfinder.

I buy a thermostat from Napa for $8.
How difficult can it be?
Pretty damn difficult, that's how difficult.


Mechanical Thermostat
This is a spring loaded valve.  At a specified temperature, 180° F, the valve opens.  This allows HOT water from the engine to circulate through the radiator to cool.

Pathfinder Thermostat Pathfinder Thermostat

But first, lets pay some bills:

  1. I Used:
    • Make a gasket paper
    • Make a gasket RTV silicone stuff
    • 12 mm socket
    • Magnet on a stick

    Pathfinder Thermostat Repair Materials: Gasket Paper, RTV Silicone, Magnet

  2. I drained the radiator out of the stupid leaky as hell drain COCK (I had to remove the skid plate to get to it).
    Pathfinder Drain Radiator Coolant through Draincock

  3. Removed the upper radiator hose and fan shroud.
    Pathfinder upper radiator hose and fan shroud

  4. Unbolted the lower hose pipe, removed the pipe from the thermostat hose, and removed the hose from the radiator.
    Pathfinder radiator thermostat hose pipe

  5. Before I remove the thermostat housing, it might help to mark which side is up - with liquid paper or something.   Luckily, mine has this little "flange" or whatever on the up side.   Also I was taking these pictures and that helped a lot.   Removed thermostat housing - 3 bolts, 12mm.   I actually did it with the fan shroud still in.   Big mistake.  The shroud is so easy to remove and install and makes a huge difference.
    Remove Pathfinder Thermostat Housing Bolts

  6. Used one of those telescoping magnet pointer things to find the bolts that held the thermostat.  . One of the bolts is in the pan of coolant under the car, one is behind the water pump pulley, and the third bolt is actually balanced on the main pulley behind a belt where I can not see it from any angle.

  7. Removed the thermostat - I grabbed it with a pair of pliers.  It came out easily, I just needed a grip.
    Remove Pathfinder Thermostat with Pliers

  8. Cleaned pipes with putty knife, sandpaper, wire brush
    Clean Pathfinder Radiator pipes corrosion

  9. Made a new gasket - The guy at Napa said I didn't need a new paper gasket.   He said the "Water Pump and Thermostat RTV Silicone" was all I needed.   But darnit, there was a paper gasket and silicone in there originally, so I traced the old one and cut out a new one.
    Pathfinder Thermostat make a gasket paper

  10. Installed the new thermostat with the "jiggle valve" up.
    Pathfinder Thermostat installation jiggle valve

  11. Gooped up the housing gasket with RTV silicone gasket maker (no pic because I was trying to hurry (and I was covered with silicone)).

  12. Tried to install the thermostat housing.

  13. Got the magnet and started looking for the bolts I dropped.

  14. Cleaned the semi hard silicone off the gasket and started over.

  15. Installed the housing.

  16. Iceed my back and curseed the bastard who designed this nightmare.

  17. Reinstalled the pipe and the lower hose.
    - Made sure all the clamps are on the hoses BEFORE I installed them (oops).
    - That "extra" bolt holds the pipe.

  18. Installed fan shroud - gently, slowly, watch those nice radiator fins.

  19. Installed upper hose - I routeed that little reservoir hose below the upper hose.

  20. The silicone says hardens in 24 hours.  I waited 20 hours before I filled it up and started the engine.

  21. Next I sold out to make 02ยข so I can fulfill my lifelong dream of owning a 1986 944 with blown head gaskets.

    But no minivans!

  22. Then I finished my beer.

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Think: Cars are expensive, powerful, and heavy.   Before I start work, I face the possibility that I will destroy my vehicle, my own life, and innocent pedestrians' lives.   If anyone messes with a 4000 lb machine capable of 100 mph, these are real possibilities.   If I get in over my head, I call a professional mechanic.   The information on this website is provided only for entertainment purposes, and it is not intended as advice on how to service a vehicle.   For all you know I made this up.   Don`t believe everything you read on the internet.

Disclaimer: The technical information in these documents is provided without any warranty whatsoever and at no cost.   All information is in general terms and is not meant to apply to your particular situation, be current at the time you read it, or even be correct in the first place.   Improperly maintained vehicles can lead to serious injury, death, or unavoidable accidents. The author is not responsible for any errors on this site, and does not make any claim at all about the validity, safety, or veracity of the information contained on this website. Any work you choose to do or not to do on your vehicle is done at your own risk. The information on this site is not intended to serve as a replacement for professional advice, professional workmanship, dealer service, union labor, or psychological counseling.   The author disclaims any and all liability directly or indirectly arising from the application or use of any information or idea contained on this or any other web site.   By opening this page, you agree to never sue anyone ever or allow anyone to be sued on your behalf.   The appropriate professional should be consulted regarding your specific condition. does not take responsibility for the information posted on other sites to which it links.

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Last modified: 11/22/2014