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DIY - Pathfinder Mod

Old 07-08-2015, 01:24 PM
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cyc5181
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Default DIY - Pathfinder Mod

When I searched for a DIY on this and couldn't find one, I thought to myself it must be easy enough that no one feels the need to write one. Well, turns out it's a little more complicated than oil change so I hope this will help others when they do this.

Started easy enough by draining the coolant. Then taking the intake tube and the plenums out of the way. If you need instructions on this, you can go to Motordyne and get the instructions. http://www.motordyneengineering.com/manual.pdf

After that I took the passenger coolant pipe out. That was all i did on the first day.


remove instake tube, upper/lower plenum, passenger coolant pipe



How it looks without the upper/lower plenums

Next I disconnect all the hoses connecting the oem coolant pipe to remove it. 4 nuts (12mm I think) holding it to the block. and yes, you'll need to fight with harnesses to get that pipe out. Also you need to loosen the transmission breather hose in order to get the pipe out.



from FSM


2 bolts on the back of the oem pipe holding harnesses and brackets


comparison between the oem and the PF pipe

Notice the hose connection. the PF pipe is missing the bypass connection (it connects back to the passenger coolant pipe). So the hose on the left side is useless. The one on the right side fits at the long nipple connection on the PF pipe, and the t-stat sensor is back at where the hole is (next to the additional t-stat on the left) There's another connection that blocked off next to the t-stat connection, I used that to put my water temp gauge sender unit in.


you'll need to drill a hole, and use a tap and dye tool to make threads to connect the sender unit to the PF pipe

Next comes the uncharted territory for me: removing the fuel rails and the intake manifold. Turns out it wasn't too bad, I didn't need to remove the injectors so no fuel leaks. unplug the connectors to the injectors. remove the 4 bolts holding the rails in place, and 8 bolts/nuts holding the intake manifold. There's a bracket on the back of the manifold that you need to remove as well.






From there you should be able to see the square plate with 4 bolts holding it, that's where the new connection goes.

now you're ready to re-install everything.

I first put the PF pipe in first, using the 4 nuts to hold it in place. Then I connect the new connection to the new t-stat.


how it looks with the new connection to the PF pipe

Well, everything went pretty smooth until this point. I then tried to plug the oem t-stat sensor back, only to realize the harness is now too short......... so I had to extend it. Kinda scary if you never have to cut up your oem wires.......



and now comes the scariest part...... cutting the passenger coolant pipe! I never knew the PF mod requires any cutting, always thought it's plug and play. But since I couldn't find any DIY or any instructions, I didn't know until I tried to line up the 2 pipes together!


PF pipe is longer and uses a different connection to connect to the passenger coolant pipe


another comparison of the oem pipe and the PF pipe, notice the difference in length and connection that connects to the passenger pipe.


how much you need to cut to make it work. Also remember I said earlier about the bypass connection being useless? That little nipple on top parallel to the passenger pipe now needs to be cap off.

And if you're still reading this, congrats you've done 80% of the work! And the worst is over! Now all you need to do is putting everything back together, make sure you tq the intake bolts/nuts to spec according to FSM/Motordyne.

While I had the plenums out, I also replaced the spark plugs. It's much easier to access them with the plenums out imo. There's a DIY post here on how to replace them. That's what I used as my guide.

I just finished all the work above this past weekend. Still haven't fill coolant in order to test everything. Hopefully the car runs like it has always been when I start her up. Praying I didn't miss a connection here or there, all bolts are tightened correctly (no leaks!), etc etc........ I need to finish this before next weekend so I can go to a DE event.

So far, I think I've spent about 20hrs or so on this at a leisure pace. I also installed the water temp gauge which is also new to me (took me forever to figure out what color wire is the switched 12V at the radio......... smh noob ) So in 20hrs, I've replaced the oem coolant pipe with PF pipe, installed a water temp gauge, and replaced spark plugs.

Update 7/20/2015:
Just went to an DE event this past weekend and wanted to share what I found. Weather was in the high 90s, possibly reach 100+ on track in TX heat at TWS. The car ran flawlessly. Highest temp the car reached while on the tracking running is 228F. The car mostly run in the 200-220 range, I only have time to check the gauge during the straights and that's what I had seen reading. I don't have any data on water temp before doing the PF mod so this is not really a comparison, more like a FYI. The car also has an oil cooler and a AMS radiator (don't know the size).

Last edited by cyc5181; 07-20-2015 at 06:22 AM. Reason: update
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Old 07-08-2015, 06:34 PM
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jv350z
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Good stuff. thanks.
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Old 07-10-2015, 12:45 PM
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G4nismo
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forgive me but so what is the main advantage of the PF pipe over the oem one?
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Old 07-12-2015, 10:32 AM
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cyc5181
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Originally Posted by G4nismo View Post
forgive me but so what is the main advantage of the PF pipe over the oem one?
In short, it helps coolant circulates the engine better as it provides an additional outlet to the rear pipe.
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Old 07-12-2015, 11:37 AM
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Before doing this mod, keep in mind, the new pipe on the back of the motor no longer has a bend to allow remove of the cam sensor on the passenger's side. If your sensor goes bad, you'll have to drain the coolant and unbolt the pipe to remove it.
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Old 07-12-2015, 01:45 PM
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cyc5181
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Originally Posted by i8acobra View Post
Before doing this mod, keep in mind, the new pipe on the back of the motor no longer has a bend to allow remove of the cam sensor on the passenger's side. If your sensor goes bad, you'll have to drain the coolant and unbolt the pipe to remove it.
good to know! but a little late for me, hahaha
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Old 02-01-2019, 06:33 AM
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EDIT: Thanks to bealljk for providing a video of his engine where he poured water into this area and showed it draining through to the coolant pathways in the block. For some reason on the 2 engines I have (DE and REVUP) that does not happen though, hence my post below. Maybe its different on engines in different parts of the world? I'm in the UK

Sorry to bump such an old thread but this seems to be the main one on here discussing how to install this mod.

I'm genuinely worried that most people who've done this mod are getting absolutely no benefit from it because the port on the block that you think you now have allowed coolant to flow out of (and into the new thermostat) is actually a complete dead end inside. I mean unless my DE engine is completely different to everyone else's... But here's what I see when I take that square plate off the engine



might be hard to see in the photo but I've had my hands in there and it's definitely completely sealed off. So just replacing the plate that sits on top of that with a new one that has a hose coming off it is definitely not allowing coolant to flow out of there. All it would do is allow some coolant to pool up in there once the new thermostat opens... Which is not how it works on the pathfinder or what this mod is meant to do for us.

So am I missing something? Have other people drilled inside there to allow coolant to come out? Or is this mod actually doing nothing for most people who've installed it?

Last edited by ChrisDe; 02-02-2019 at 10:15 AM.
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