How to Replace Thermostat 1996-2004 Nissan Pathfinder

Hi, I'm Mike with 1A Auto. We've been selling auto parts for over 30 years!

In this video we're going to be removing, and installing a new thermostat in a 2000 Nissan Pathfinder. If you need parts for your vehicle, click the link in the description and head over to 1aauto.com. All right we're going to pop the hood right here, pull that lever. There's a release right here. If you go the center, and to the right a little bit, right there. We're going to grab the pop rod, and put it right there. We're going to disconnect the negative terminal in the battery with a 10 millimeter wrench, loosen it up. Get it a little looser. We're going to pull that out, and set that aside.

All right pull these two clips over here, right here, and right here. There's two clips over here, and then this one gets pulled up from down underneath. Pull up, pull the air filter up. We'll use a straight blade screwdriver, pull this hose off. Over here, I'm going to disconnect the connector right here. There's a button on the back side. Push it down. Pull the connector off. This is the connector from the mass airflow sensor. Disconnect that. Little retainer right here. Pull that off.

Take this clip off here, so we can move the throttle cable out of the way. We'll take this one off too, and that one there. Just push it out of the way. We can use a straight blade screw driver. Loosen up the one clamp on the throttle body. We can loosen this up. Pull that out of the way, and then pull these hoses off using some Channel Lock pliers. Just cinch the clamp, and then twist it back, and forth. Do the same for this one. We can pull this box out of the way. I need to take this lower cover off. I have a 10 millimeter bolt here. They may have been other bolts here, this vehicle is missing some. I'll take this one off. Use a 10 millimeter socket, and extension, and a ratchet. Over here there's a bolt. There's one right here. There be one right there, and right there, and right here, and pull it down. This lower part of the fan shroud had to come off. I'm going to take and grab the center right here. Pull it past that little nub right there. We should be able to slide this out. Up here on the fan shroud, as you can see there's a little tab right there. Can you see it? You're going to push down on that tab. You can pull out, and it's going to release the lower part of the fan shroud.

Then do the same for the other side. Little tricky to get your hands up in here. Let's see. I'll take that piece off. You can rotate it, and pull it down, pull it out. These little clips right here on both sides. We're going to drain the coolant. This vehicle does not have a pep cock on the radiator, so what we're going to do is disconnect the lower radiator hose. We're going to have something to drain the coolant into. We'll grab it, grab this clamp with some Channel Lock pliers, and move it to the side. I'm going to use one of these picks, like a right angle pick. We actually sell a kit of these at 1aauto.com. You can take, and get it right in here. Go all around the hose. That'll loosen it up. Be careful not to get it all over you. You don't want to take a shower in it. Once that's drained, leave that out of the way. A little bit or rust on this clamp up here. I'm just going to spray it with some rust penetrant, before I try to take off the clamp. Let me get some Channel Locks to hold it, so it doesn't twist while I'm doing this. Just like this. Loosen this bolt up. As I loosen the bolt, it loosens up on the clamp.

Pull that clamp aside. I can grab the radiator hose, twist it a little bit, peel it off. Next we're going to take those hose off right here. There's a clamp right here. You just grab it with your fingers, pinch it, and pull that off, and it'll pull the hose off over here. That goes to the coolant, reservoir, and we'll just set that aside. Next I'm going to take this 10 millimeter bolt out on the fan shroud with a 10 millimeter socket, and a ratchet. We'll take this one as well. Pull that bolt out. Then the fan shroud should be loose. I'm just going to pull this up over here. Once I pull that up, then I'll be able to clear this hose over here. Pull it up over there, gently pull it out. Before we pull the belts off, we're going to take this fan, these nuts for the fan, and we're just going to loosen them up. We're not going to take them out completely, we just want to crack them free. It'll be easier to do it while the belt it still on there. We take our 10 millimeter wench, get in here, just track it free, track this one free. Track this one free.

Sometimes you might have to hold the belt if it's really tight. Then this bottom one. Once those cracked free we can take the belts off. Okay, first we're going to take off this AC belt. The tensioner is right here. It's not an automatic tensioner, so it's a manual tensioner. We're going to have to start by loosening this nut right here on the front of it. It's a 14 millimeter, just loosen it about a half a turn. Then the adjuster if over here. I'm going to use a 14 millimeter socket, and start loosening it. As we loosen it the belt is getting looser. The tensioner is going down.

We can take the belt off here just like that, and bring it around the fan. We are reusing these belts, because they're new. If we were replacing them, this would not make a difference, but we want to label these from where they came off, so you don't put them in the wrong part. We're going to put AC on this one, because it's the AC belt. We'll label the others as we go. Next we're going to take off the drive belt. This drives the alternator, and the water pump, and that's it.

The tensioner is right here. We're going to use a 14 millimeter socket, and a ratchet, and I'll just crack this free. Just go about a half turn. Then the adjuster is over here on the side. The adjuster for this is a 12 millimeter, so we're going to use a 12 millimeter socket, and extension, and a ratchet. We're going to loosen this up. That's going to bring the tensioner up, and take the tension off the belt. Once there's enough tension off the belt, you should be able to slide it off. Take it off here, and go around the fan just like this, just like that. This one is the drive belt, so we'll label it drive. We're going to get this power steering pump belt off. We need to raise the front of the vehicle. We have a 12 millimeter wrench that we're going to loosen this nut up just a little bit. Crack it free maybe a half turn, maybe a whole turn. That's about good. Then the adjuster is over here on the side. Somewhat hard to get to with a 12 millimeter. You can loosen it with a wrench, or a ratchet wrench. You might be able to get a small socket, and ratchet in there. Try it with a 12 millimeter socket, and ratchet. Just loosen this. As we're loosening this, you can pull on the belt, and that will pull the power steering pump down.

This is loose enough I can do it by hand. Just keep pulling it down. All right. Now I'm able to fold the belt up and over, and off the power steering pump. Then I'll take it off the crank, and pull it down. Now that we have the belt off, I'm going to take the rest of the nuts off of this fan, and pull the fan out of our way. Can use a 10 millimeter wrench if they're still tight. I'm going to get the last one almost out, make sure you're holding the fan, so it does not fall out. You don't want it to hit the radiator, because it could damage the radiator.

We'll grab the fan, pull it gently, and you can pull the fan out. This water pump pulley will come right out. We're going to take this bolt out right here for the bracket that holds this lower radiator hose on. It's a 12 millimeter. I'm using a 12 millimeter socket with an extension, and a ratchet. We're going to loosen up the clamp with a 10 millimeter socket, and a ratchet. It's a little rusty, so spray a little rust penetrant on it, and let that sit for a second. I'm going to hold this bracket with some Channel Lock pliers, and then loosen it up.

Pull that clamp out of the way, and get in there with our pick. Should be able to twist, grab the hose and twist. Use our pick again. Go all the way around--that'll break the seal on the hose. Now it's loose. Just pry it back, and forth, you should be able to pull it off just like that. We're going to pull the thermostat out. We've got three 12 millimeter bolts on this. Take these bolts out with a 12 millimeter socket, extension, and a ratchet. I'm going to pull that last bolt out. As you can see we have a lot of room here. We pulled some of this stuff out just to make the video better, but you don't have to take everything out that you don't see.

You can do this with more of the stuff in the way, but for the sake of the video we pulled it out. Okay. I'm going to take a pry bar and stick it under here. Just going to pry out on the thermostat housing just like that. It's actually glued on, and I can pull it off. We actually sell these pry bars at 1aauto.com. Just going to grab this with some Channel Lock pliers just like this. Just grab it, and pull it out. There's our old thermostat.

I'm going to clean up some of the sealer with a rag, and some brake parts cleaner. Just get that all clean. If there's a little bit of RTV to scrap, you can scrape it off here. This gasket scraper. We sell these at 1aauto.com. Now we're going to scrape the gasket material off the housing using the same scraper. We're going to install the new thermostat. There's a little breather right here. You always want that breather at the top, so the air bubbles can go through there. Insert that right like that.

We're going to take the housing. We're going to use some gray RTV engine sealant, and just put a thin, real thin bead all along. Very thin, go around all the holes just like that. Make sure your thermostat is pushed in. We'll take our housing, and line the holes up, and push that on. Put our bolts in. Take a socket, and get the other ones started. Get this other bolt in. That one started, and then this last one. With my ratchet snug these all down. I'm going to torque these bolts to 150 inch pounds. Make sure you're using an inch pounds torque wrench, not foot pounds.

We're going to put the power steering pump belt on. Normally you have the coolant fan on here. We had the fan off at this time, make it easier to see. We're going to wrap this belt around the crank, on the back side of the crank pulley. That's where the V channel goes. Then over here on to the power steering pump. We'll start it at the top, and then we'll try to locate it down just like that. We're going to tighten up the adjuster screw right here. It's a 12 millimeter, I'm using a 12 millimeter socket with a ratchet.

I'm just going to tighten this to get more tension on the belt. Now we can reinstall this hose. Turn this ... Now we'll reinstall this hose. Stick this here. We can tighten that hose clamp down, there's a 10 millimeter socket extension, and a ratchet. We'll tighten this hose clamp down. We'll clamp that down so it's snug, and install this bolt here. Install this bolt here. It's a 12 millimeter bolt, we'll tighten it down with a 12 millimeter socket, and extension.

We're going to install the fan next. We're using a ratchet wrench to tighten these nuts down. You're not going to be able to get a torque wrench in here. Just do the best you can. Once we put the belts on, you can snug them up a little bit more. Next we'll take our drive belt, pull the tape off that we labeled it with. Now when you're putting this on, you'll still have your radiator shroud here. You can sneak it past there, and go around the fan just like so. You're going to have the belts start at the crank, it's going to come up to the water pump. It's going to go back here on the alternator.

Once it's around all three of those, you can put it under our tensioner pulley. Now we got to tighten up the tensioner pulley right here. We'll take a 12 millimeter socket, and extension, and a ratchet, and we'll tighten up the tensioner pulley. Right here when we push down on it, we're looking for about a quarter inch of deflection. That one probably about good there. If you find that the belts squeal, you may want to tighten it up a little bit more, and you may have to tighten if they stretch a little bit.

Now I'll tighten this bolt up for the tensioner. Lock that down. That's pretty good and tight. Now we'll take our AC belt that we labeled. Pull the tape off. We'll slip it over the fan. It's going to go around the crank down below. It's going to come up around, and on the compressor, and then up and over the tensioner. Oops, it slipped off the crank just like that. Now I'm going to tighten the tensioner right here with this adjuster, and you need a 14 millimeter socket, and an extension, and a ratchet, and tighten this up. Make sure it's around your pulleys in all the grooves.

The same here. We're looking for about a quarter inch of deflection. We'll tighten this a little more. That's about good. All right. Now we'll tighten this nut down. That's snug. If any of these end up squealing, or loosen up in a couple of days of driving, then just snug them up a little bit more. After you install the belts, you're going to want to tighten these nuts up for the fan. Get in there with your 10 millimeter wrench, and make sure those are snug. Now we're going to put our radiator fan shroud on, and slide this over. It's a little bit tight over here. Just snug it under here just like that.

There's some pins--it lines up down here, and then same on the other side. Make sure that's in, and then we'll put the two bolts in. Take this bolt right here, and this one right here. We'll tighten these two up with a 10 millimeter socket, and a ratchet. Same with this one. We'll put this hose on, the radiator hose. Get this clamp lined up. Use a 10 millimeter ratchet and tighten this down. Make sure that's snug. Pull this throttle cable down, click that in place, and then this goes in over here like that. Take the air filter, put the air filter back in. We'll take the air box. It's going to slide in under here. There we go. Click that in there. Click this in here. Click this right here. Click this one right here. We'll click this hose on here. There's another coolant hose. This goes to your overflow. It gets clicked in over here, here, pushed on there. Then this is going to go right here. Connect that snorkel to the throttle body, and these two little breather hoses.

Grab my pliers squeeze this, put that on there. Then this one can go on here. This clamp with my Channel Lock pliers. Push that one. We';ll take this, we'll tighten that up right here. Tighten this up, this one clamp up with an eight millimeter socket, and a ratchet, and an extension. Make sure it's all the way down. Looks good. Snug that up. This goes underneath this clip just like that. This wire right here goes over to here. If this clip wasn't broken, it would secure right there, and this plugs into the mass air flow sensor like that. Now we're going to put this lower fan shroud on. Get this lined up here.

Get the top part lined up, and now clip in. This will clip in, and then this should clip in. There it goes. Locked in, make sure that tab is in there. Looks good. Put this lower shield back up. This shield does not have all the bolts, so we may have more than what we have here. We may have bolts there, there and there. This one does not have those bolts. Put this one here. Good. I'm going to connect the negative post to the battery. Tighten it up with a 10 millimeter wrench. Okay.

Now we're going to want to add our coolant. You can use a funnel, add your 50 / 50 mix of coolant in there. We're going to fill it up, and then bleed it. Whenever you replace any internal engine components, or you're draining the coolant for any reason. You're going to want to add your coolant here into the radiator. You cannot add the coolant just the reservoir, because the engine will not get any of the coolant. Add it to the reservoir. If you're checking your engine coolant on a regular basis, you can just check the reservoir, and top that off.

We're going to add our 50 / 50 mix of coolant, and water. As we're adding this, it's a good idea to look underneath the vehicle, and check, and see if there's anything leaking out. Ours looks good. Okay so there is some air in the system still, even though we have the coolant all the way filled. The radiator is full of coolant. The engine still has some air pockets in it. What we're going to do is we're going to start the vehicle and let the engine run for about 10 minutes.

All right we let the vehicle run for about 10 minutes. As you can see the coolant temperature, we want to keep monitoring it while we're letting it run. We want it about half way in between the cold, and the hot. This vehicle doesn't have temperature readings, so you just have to use your best judgements. If you start seeing it go up to about 3/4 above, not in the half way back. You're going to want to stop, shut the vehicle off. Let the vehicle cool down, and then re bleed it, re check your levels, and start over.

All right we let the engine run for about 10 minutes, and the engine got up to operating temperature, and the thermostat opened, and all the air bleeded out of the engine, and came out our funnel, and everything is all bled, everything is good. At this point, what I'm going to do is with this funnel, stick this plug in here, and then I can pull the funnel up, and make sure the level is right up to the top of the radiator. With the engine still hot I will put this radiator cap on, and we will let the engine cool down.

We are going to want to check before we just let it cool down, the coolant reservoir, and make sure the coolant reservoir has enough coolant in it. I like to go about an inch above the fill line when doing this procedure, because it is going to suck back in some coolant, and then you can adjust once the engine is cool. I'm going to add this coolant to the reservoir. If you don't have one of these funnels, that's okay. When you're bleeding the system, you can leave the radiator cap off while you're running the engine.

You're just going to have to monitor it closely, so that you don't lose coolant. You're going to have to stand here with your coolant bottle, and keep adding coolant. If it starts coming out, then shut the engine off, and start the bleed procedure again.

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