Jack’s Old & Busted Blog

If you’ve googled this, you already know the heartache of replacing what should be a simple part (This is assuming you have a four-cylinder model). When you finish this procedure, you will want to punch the engineer that thoughtlessly located the thermostat beneath the power steering pump. What was going through their heads? “Thermostat replacement has been a relatively trivial task since the conception of the water-cooled internal-combustion engine,” they might have said. “How can we muck this process up completely?” In lieu of hunting the idiot engineer who made this decision and forcing him at gunpoint to replace your thermostat himself, here are some useful tips (disclaimer: This is your truck, not mine. If you muck it up even further or injure yourself by following any advice given here, it’s your own fault for following advice you found on the internets from some shade-tree mechanic.):

1. Loosen the power steering idler-pulley axle bolt. This will make it easier to move the adjuster that slackens the PS belt.
2. Remove the belt (take it completely off for now).
3. Remove the power steering pump by removing the three bolts on the front (you have to thread your socket through slots in the pulley), and the one bolt on top near the manifold (not load bearing, but it’s there for some reason).
4. Set the PS pump aside the engine compartment. You won’t need to disconnect the hoses; it’ll sit just fine.
5. Remove the plastic shield from beneath the motor and put a big bucket underneath for coolant that will leak out in the next step.
6. Remove the hose from the thermostat housing (this makes it much easier to reinstall.
7. Remove the housing via the three bolts. The bottom one is conveniently obscured by another belt, which you can deflect slightly for access.
8. Scrape off the gasket material (or gasket, if you have one - some just use silicone). Use one of those green kitchen scouring pads to give it a nice, smooth surface. do the same to the engine side gasket surface. This takes awhile to get right, but will save you the heartache of doing it right the second time.
9. This is important: the replacement 170-degree thermostat does not need the rubber o-ring thingy it comes with. It fits nicely in a flange without it. Make sure the “bubble valve” is on top.
10. Using a new gasket, smear a thin coating (using your fingers) of RTV silicone sealant on both sides. Align on housing with bolts installed. It only fits one way, cuz one hole is offset.
11. Carefully replace the housing (you removed the hose, right?). The three bolts do not need to be tight, just snug. It’s more important that they be evenly snug.
12. Reconnect hose to housing.
13. Fill ‘er up with your favorite coolant. Leave the cap off for now.
14. After checking that you have removed all tools and other stuff from the engine compartment, and that the PS pump is safely out of the way, start ‘er up and check for leaks. Let the engine warm up so you can see the coolant flowing when the new ’stat kicks in. Add more coolant to top it off. Replace cap.
15. Replace PS pump. Remember there are four bolts. Remember to tighten the adjuster pulley axle bolt after you have tensioned the belt.
16. Curse the Nissan engineer for wasting your time.