hawairish

The pinion is not disturbed, but because the carrier gets pulled with ring attached, the backlash needs to be set again. Ideally you’ll check backlash first in a few spots before undoing anything so you can try to hit those numbers again (or otherwise hit within the spec range).

So get this: I just took a closer look at my previous thermostat, which I had no reason to check previously because FSM says it's supposed to be a 170F unit, but it's a 180F unit. I guess my solution is to use a 180F unit. As far as I can tell, all the wiring is solid. I specifically inspected the loom for any damages the other weekend because all 3 of the codes conveniently relate to all three of the harnesses in the same wiring pigtail. I presume the wiring is fine because I was closely and constantly monitoring live data on my scanner and everything always seemed reasonable at all times. Now I need wrap my head around this. I'm guessing the previous owner installed an aftermarket 180F unit; looks like one on RA. The OE 170F unit fits 00-04 R50 and 03-08 350Z. FSM specs closure at 160F, which could explain why my temp seemed to regulate in the low/mid 160s in steady driving conditions. The 05-08 Frontier/X/R51 uses the 180F unit on its VQ40, but the housings is identical to VQ35 unit. I'd be using the R51 unit, essentially. Just trying to figure out why my ECU may ultimately need the 180F unit if it's supposedly "programmed" for a 170F unit. When researching the P0128 code online, I did see occasional mentions about some auto manufacturers needing to flash ECUs after thermostat changes, but that seemed like a bunch of fluff. But maybe that's the case here and my ECU now expects a 180F unit? I do see a few Nissan TSBs specifically about P0128, but nothing that pertains to my truck. Oddly, I see the VQ40 doesn't have a water control valve. I noticed the JDM R50 VQ35 doesn't have it either. Makes me wonder if there's any benefit to capping the intake manifold passage to the WCV. Such a crap design, too...spills coolant all over the top of the manifold around the knock sensor that's also buried in there. WTF Nissan.

@adamzan Aftermarket unit. It did test fine with water in a pot on the stove measured with thermometer and I ran a few tests to confirm open/close. Seemed gradual enough each time. But I think main thing here is that it stayed closed and sealed (confirmed) below 170F. The code suggests a stuck-open thermostat would cause the problem. I can see covering the radiator as necessary where you're at, but winters here are usually 50-70F/10-20C. Shouldn't be that detrimental here. Drove the truck for hours straight through freeway mountains over the past few weeks and still threw the code. I wonder if poor coolant circulation could cause this. FSM makes absolutely no mention of the water pump for this code, and I absolutely don't want to mess with that unless I'm 100% certain it's a problem. Maybe I'll temporarily replace a hose or two with some vinyl tubing and see how it flows.

Yeah, it's a silly code. The reason I don't believe there's an air pocket around the temp sensor is because the sensor and water control valve are on a crossover pipe that runs between the heads and has an output that wraps around the passenger side of the engine to the upper radiator hose, which exits higher than the crossover pipe. In the pic below, the sensor is by the dragon logo, and the WCV housing to its left. The Y-pipe by cylinder 3 runs to the heater core. The heater core return line is the black pipe running along the firewall. The little vertical tube with a rubber cap on it is the vent tube That is the high point of the system. As such, with enough drives (I spent a good chunk of Monday driving around to perform the drive patterns to get the truck emissions ready), I'd expect any air to roll out of the crossover tube pretty easily. The only place I'd expect trapped air at this point would be at the WCV on the intake plenum side if the coolant did not reach 203F to dump it into the crossover pipe and circulate it. Air on that side is inconsequential, though. Full system flow: Breather tube is on the "from heater" line. "To|From intake manifold collector" runs through the throttle body opening. I do have a radiator funnel and was using it exactly as you mentioned. Ran the truck a few times and let it sit. Eventually when I determined the vent tube was clogged and drilled it out (the tube and pipe is steel, so I'm guessing the persistent coolant level over the years just corroded where sat), I still had the funnel attached and about half full. I could tell coolant was circulating somewhat because crud I couldn't vacuum out eventually surfaced in the funnel. The thermostat is actually a triangular thermostat housing assembly that can only be installed one way; the thermostat part of it isn't replaceable, but yes, the valve was upward. Mine has a water inlet port for the oil cooler on ATs. The WCV is a normal thermostat shape, and it's installed flat; it's installed in a manner that allows coolant to flow across the thermostat body without being obstructed by the supporting vanes (as described in the FSM, no less). Everything said, I have also not seen any leaks whatsoever. All gaskets replaced, tightened to FSM spec. I was throwing these 3 codes: P0128 - this mess P0171 - Bank 1 fuel injection system too lean P1148 - Bank 1 closed loop control (faulty passenger upper O2 sensor) Part of my overhaul in August included new spark plugs, reconditioning the fuel injectors (cleaned, new o-rings, new pintles, new filters), and replacing all 4 O2 sensors. Long story short is I've been having all sorts of fuel/O2 issues since the overhaul, which is blowing my mind since I set out to prevent all these issues and chase some other code that popped up once a year that I can't recall. I just tore the engine down again (four times in as many months?!) maybe 2 weeks ago to troubleshoot all 3 codes. My thought process, given all the codes, is that if the passenger bank was in fact running lean, then maybe half the engine wasn't getting hot enough. The spiral seemed a faulty O2 sensor causing lean condition causing insufficient engine heating. P0171 suggests a lot of things, including a leak in the exhaust; that seemed the most plausible while other suggestions seemed implausible. There's a massive backstory bull$h1t fiasco regarding trying to replace the catalytic converters during the overhaul and even up to last week, but let's just say I finally replaced the gaskets on the cats. I'll note the passenger cats and exhaust manifold were very sooted over...a far cry from a too-lean condition, but possibly sooted from when I was initially dealing with a rich condition months prior. I also pulled all the plugs, injectors, and coil packs again, cleaned everything again, and moved them all around to different positions. The code has not resurfaced. P1148 was pretty specific to the upper passenger O2 sensor. I monitored the voltages on all the sensors with my scanner over the course of several drives and observed that the nominal voltage for it was not fluctuating as it should per FSM. All other sensors were fine. I'm still bitter about having the most difficult sensor to replace be the one that failed. The other 3 are easy. Replacing this one sucks tremendously and basically requires pulling the cats. New sensor is functioning as expected. Code has not resurfaced. One additional notable: I installed an aftermarket transmission cooler during the overall and initially ran it in series with the OE cooler built into the bottom of the radiator. I eventually bypassed the aftermarket cooler and reverted to using only the OE cooler when dealing with some other performance issues that surfaced. I still threw the P0128 code in the stock configuration. Just the other week I hooked the aftermarket cooler back up and bypassed the OE cooler. All said (and sorry for a long post), only P0128 persists now, fortunately. I was scrambling to get it emissions ready because my tags expire at the end of the month. The P0128 code resurfaced as Pending code on the drive to the emissions station, which fortunately doesn't prevent passing. As far as I can tell, the system is finally in top shape (my test drives on Monday were yielding 14-15 MPG, which is worlds better than it has been and pretty solid for my configuration), so this code feels like a lot of tail chasing. I may just block part of the radiator and call it a day. What I'd really like to know is if I can just tweak the coolant ratio to reduce efficiency so the temp will be hotter.

Hey fellas, this one has me stumped and I've been fighting it for several weeks. Been throwing P0128 codes, which indicates that the engine temp is not reaching normal operating temps. This is on my 04 R50 3.5L and I believe it's been doing it since August when I did a bit of an engine overhaul. Here's what I can tell you: Installed new thermostat and water control valve. Also installed new gaskets, upper/lower hoses, and replaced coolant. I run 50/50 per FSM. I refilled with a gallon of concentrate, a gallon of distilled, then topped it off/overflow with pre-mixed 50/50. I've idled and revved the engine per FSM, put it on ramps, and otherwise attempted to get any air out several times. Repeated hot/cold engine cycles and top-offs. The rear breather tube was clogged, so I drilled the crud out and got it to a point where coolant eventually spurted out. (For those not familiar, there is a vent tube above the engine at the center of the firewall.) That is the high point in the system. FSM says coolant should come out that, but seems impossible considering it's a few inches higher than the radiator neck. The FSM and internet suggest the #1 culprit is a thermostat stuck open. Again, brand new, but I pulled it for testing. Was closed when cool; the neck held water. It opened at 170F as spec'd in hot water. Closed again in cool water. Thermostat is working perfectly. I also tested the water control valve because I had everything apart. Was closed, then opened at 203F as spec'd, closed at anything cooler. Water control valve is working perfectly. Pulled the temperature sensor. Per FSM, measured resistance at several temps from 68F-194F and it remained in spec at all points. Temperature sensor is working perfectly. With engine off, noticed a tiny screech noise when turning the fan clutch by hand, and there was a little wobble when it was warmed up. Installed new fan clutch, new fan blade, and new radiator cap two weekends ago thinking maybe the clutch had too much load at lower RPM. New clutch didn't feel much different, but it's clear it's performing differently (better) than the old clutch was. ECU seems fine. It reports changes in coolant temp and they seem accurate enough. I was also monitoring other sensors; ECU responded as expected. Cycled heating and cooling modes in the cabin; blows hot/cold respectively. My scanner shows that the truck only hits about 132-140F when idling for about 10-15 mins. On steady drives, observed operating temp is around 158-166F. I presume operating temp needs to be above 170F; internet says 195-220F is normal. Temp gauge reads slightly below 50%, and always has for as long as I've owned the truck. Ambient temps around me are about 50-70F this time of year, but it was "underheating" during the fall, and it's been underheating on recent long (6-8hr) freeway hauls, too. Heater seems to work just fine. Since I've been fighting to resolve two other engine codes, I've needed the truck to hit 158F at idle and I've only been able to do so by obstructing the radiator about 40-60%. I could only get it to hit 180-190F at nearly 100% radiator obstruction and revving over 2K for a several minutes. Now, while I'm super pleased that I have an extremely optimal cooling system, the engine code is frustrating me. Anybody got ideas on how to increase coolant temps beyond blocking the radiator? Does it seem likely I've still got air trapped somewhere? I haven't tried tipping the truck sideways, but I might.

That's the problem, unfortunately...if you re-gear, you have to hope that the current spacers are too short so that you can add a shim to it. Otherwise can only shave it down and then maybe shim up if needed, or replace with shims. Best option has been to get the whole diff (R200, or H233B 3rd member) since it'll already be set up for the gears in it. For the H233B swap on my Frontier, I needed to move the R&P set to another housing with ABS on the snout and lucked out the existing spacers kept in within spec. I don't think I'll be as lucky if I ever get around to putting the 5.13s into the R50. Nissan did actually change the thread size of the pinion, but it went to the size we run now. The older 3rds that had 9 bolt holes to mount and 10mm bolts on the carrier had pinions with smaller shafts and nut threads. Learned that the hard way on the Frontier swap when trying to get 3.9s from an 87 D21 to work in a 93 axle. But, later W/D21 and everything up to 04 are the same size. Same pinion nut and bearings between WD21 and R50, too. Silly Nissan. That's an odd score line, but I wouldn't sweat it if the seal clears it. How did the old seal look, and was it leaking?

Got a pic?

@gsg, echoing @Slartibartfast's reply. Also curious to know how it boiled down to the control module. A faulty TFCM would disable signals to solenoids, reducing line pressure and reverting to 2WD operation by default. Something would likely need to be mechanically stuck to keep in 4WD I'd think. Also, note that the presence of the 4WD light at startup indicates a fault present in the TFCM; it doesn't necessarily mean it's in 4WD. A decent scanner can read directly from the module to retrieve any fault codes, but there is also a scanner-less self-diagnostic mode that will flash trouble codes. View the FSM chapter here: https://www.nicoclub.com/service-manual?fsm=Pathfinder%2F2004%2Ftf.pdf ATX14A sections starts on page TF-41, but see page TF-61 for the self-diagnostic mode instructions. If you do it right, it'll reward you with a series of flashes of the 4WD light and 30 extra lives in Contra. You may have more than one code; it'll blink them all before repeating the list.

Late response. 1" drop would not be advisable. Dropping the subframe and getting longer bolts is trivial, but if you omit the engine spacers then the engine lowers 1"...which means hoses, wires, intake tube, exhaust pipes, radiator fan all to flex/move relative to everything else. Putting a 1" spacer on the engine mount is easy...but since the motor mounts have integrated studs, you'd need to find a way to extend them or change the perch. Then, on top of all that, your stock steering shaft probably wouldn't have enough flex at the rag joint to accommodate the drop and the slight angle it would create (the shaft does extend, but it'd be near/at limit).

Funny thing is that when I rebuilt my D44 earlier this year, I felt like I needed a puller because the flange was RTV'd to the splines. I dislike working with RTV, but that's what manual called for. Dialing that axle in sucked. And yeah, dealing with crush sleeves seems like a pain. I've fortunately not had to deal with it. I'm also surprised that the R200 lacks a crush sleeve. It uses a fat spacer instead with "adjustable" spacers. By adjustable, I mean buying spacers that you can no longer get from Nissan, a.k.a. not adjustable.

Just replied to your PM. Summing up here for anyone else, RTV/sealant use isn't spec'd anywhere except the fill and drain plugs, but consider it optional. It is common on other diffs, as you noted, and won't hurt anything and may actually be recommended depending on the nature of the leak (if one). I usually just apply a little diff oil to the seal before tapping it in, and the same on the flange splines. I wouldn't worry about preload much here. Expanding on what Slartifbartfast mentioned, preload and pinion depth are set with a thick spacers/shims as opposed to a stack of thin shims. At the factory, they change a spacer to dial things in, and that spacer doesn't distort like stack of shims might, nor does it collapse like spacers on the other diffs mentioned. So, provided you torque the pinion nut to spec, you'll most likely be in the original preload ball park. The numbers Slart provided appear accurate for WD21, though I find it interesting they're much higher than newer H233B diffs (mine is 109-144 ft-lbs). I usually target the midpoint.

Add MIL, "Malfunction Indicator Lamp" to the verbiage. CEL = SES = MIL. Nissan uses MIL to describe their SES bulb.

Gotcha. Sorry, was browsing from the mobile site and couldn't see your location or truck. That kit looks suitable; looks fairly identical to the set I rented a few months ago. The straight socket is great for the lowers, while the crowfoot ones more suitable for the uppers due to working space.

On the VQ 3.5L, passenger side is B1, driver side is B2…and I’m fairly certain the same is true for the VG 3.3L engine. It is determined by whichever side has the forward-most cylinder.

I recommend renting a kit from a local auto parts store if you have no long-term need for them. Just be sure to check how much time they allow for loaning-out. Beyond that, if really wanting to own a kit, get something with a variety since each sensor takes a little different effort to remove. B2S1 should be fairly easy to access. B1S1 is the pain. Both S2 are easy access.

Wouldn't be viable. The WD21 axle is 4" narrower than yours, so if the goal was to get an older LSD because of the higher break-away torques (presuming the LSD wasn't worn), you'd have to do a 31-spline axle shaft swap, which I've documented here on the forum somewhere. Not worth it. Otherwise, easiest route is an LSD from a 00-04 D22 Frontier, 00-04 WD22 Xterra, or any R50 since they'll all match your axle shafts. The numbers aren't great, but if you can acquire pieces, they can be built up and I've documented that around here too. This would also be a good time to go to 4.63 gears if you've 4.36 and plan to put larger tires on later on.

Late response, but nice. Hopefully you charged them an arm and a leg to return ship the extra set. The front springs will have a wider opening than the opposite end. The rears will have the same sized ends. Possible they sent the front and rear set?

@rodskaeg If you've got an AT with that low of miles, I can understand keeping it. Hopefully it's as simple as changing the output shaft and tail housing. You probably wouldn't even need a new gauge cluster. I'd expect that the cluster still has provisions for the 4WD light, though you might just need a bulb and some donor pins to add to your harness (if not pre-wired). You should get familiar with the Factory Service Manuals if you haven't already (https://www.nicoclub.com/nissan-service-manuals). The Electrical System will have the diagrams and pinouts for the "meters and gauges". @Slartibartfast I did mean to term it with the VG/VQ interchange, but specifically to confirm that you can put a t-case from an AT or MT VG truck into a VQ truck (well, specifically a 01-04 R50 Pathfinders). But in that sense, it also confirms the MT-->AT compatibility if you grind the lip down. I presume the lip exists on MTs to cup some gear oil for seal lubrication, and I presume gear oil is present because the MT trucks require a liquid gasket on the mating surface. No liquid gasket needed on AT trucks because it's double-sealed; one seal on the transmission side, another on the t-case side (both end up on the main gear). This is setup is why the lip doesn't exist on the AT case, and why it needs to be ground down if using an MT case on an AT truck...it'll contact the transmission seal. On a related note, I highly recommend crawler gears! That's why this MT Xterra case came into the picture; I installed 4:1 (3.97:1) gears into it, along with a tapped output shaft for running a slip-yoke eliminator. I'm more familiar with this front cover than I'd like to be because I eventually needed to mill <1mm off the backside to address a binding issue, but a shakedown trip to Moab confirmed how awesome they are.

@rodskaeg What year truck is yours? If you have the 3.3L, the VSS is located on the t-case as XPLORx4 mentioned, but for the 3.5L, it's on the transmission (technically, on the tail housing). Wiring wise, I agree that a TCM wouldn't be needed. Aside from the engine-dependent VSS, the TX10 just has a Neutral switch and 4wd switch. Both could be omitted, or you could add an indicator somewhere in the cabin for 4wd if needed (neutral switch is more of a safety signal so you don't leave the case in neutral and the transmission in Park where the truck could still roll; turns on an "ATP" cluster bulb). You may even want to check if the truck was pre-wired; check under the chassis under the passenger side by the muffler for open harnesses. Doubt it was, but it's a quick look. Saw your other reply, too. Seems like you've got the right understanding of what's needed. My only thought about swapping the transmission output shaft and tail housing is that it'd be far simpler to just grab the whole transmission and t-case combination, as opposed to tearing down two transmissions and everything that entails. It might cost more, but the right unit might save significantly more time and effort and would include practically everything, including the shifter, linkage, and shifter 'gate' bracket, etc. You'd need both driveshafts, and the entire front drivetrain. Crossmember should be the same, but you'd need to confirm for you model year. Lastly, there's interchange between VG- (3.0L/3.3L) and VQ-equipped transfer cases...they all fit to the tail housing, but there are subtle differences that require you to use an R50 linkage AND the R50 t-case arm. For instance, I have t-case from an 02 Xterra 5MT on my 04 AT. The front bearing cover has a lip that I grinded off, but the Xterra linkage and arm prevented me from putting the case in 2H. Not sure if this is VG/VQ related, but something to keep in mind.

Hey @XPLORx4. Torque specs are 65-80 ft-lbs for the flange nuts. Let me know if I didn't pass our install guide over previously with those and other specs and I'll resend. While we've not heard other complaints of shifting, we're sorry to hear it happened on your truck. Do you recall how much torque have been applied previously, and whether it was tightened with the vehicle resting on the ground? Our observations during installs is that the strut mount "hat" (the OE component with embedded rubber) initially prevents the two mating surfaces of the strut spacer from being parallel until there's sufficient weight on it to flex the rubber. As for your fixed-plate idea, it may be something we can help with. I think I'm imagining it differently than you are describing, though. I follow the plate combinations for +/0/- offset, but would the plates exist inside the upper mount under the flange nuts, or elsewhere? A previous consideration of ours was to use a thicker plate with two holes, instead of using separate flat washers. This "washer" would greatly increase the surface contact area inside the upper mount, which would clamp things much better. That approach may also allow for other means to further fix the position. Anyway, feel free to carry this convo here or reach out to us directly if we can help.

Coarse stepped ones. The two larger ones have sizes that are basically perfect for the rivnuts, though I rely on calipers to confirm the diameters. You want the hole to be the same size or a hair smaller; too large and the rivnut will likely spin.

Any similar tool will do...tons of options on Amazon still varying from $30 and up. Seeing a Beetro 14" unit that's at the low price range and has the essential metric sizes. Most kits come with both SAE and metric sizes, which is a plus if you have other uses. Mine still sees occasional use so I'm keeping it around.

Got everything back together today. Cylinder 3 misfire. It's just dumping fuel...probably something stupid like I didn't fully clip in the coil, but I was too exhausted to troubleshoot any further.

Also had the engine torn down to change out the thermostats, gaskets on the rear water pipe, knock sensor, rebuild the fuel injectors, PCV, valve cover gaskets, etc. If you're going to rebuild them, get a kit with o-rings, pintle caps, and filters. Also get a filter removal tool; I was unable to remove a filter without one. Carb and choke cleaner with one of those pulse controllers off Amazon worked well to clean them, but it was a little on the messy side. And while not a Pathfinder, I tore down my Frontier on Sunday and got it to the body and paint shop. Time to bring it back to life! These pics are of the "good" side. The hood, roof, and passenger bedside are really bad. Paint shop will also do a spray-in bedliner (had a drop-in). Should have it back in a month, then will put new windshields, lenses, and rear bumper on. Btw, driving it without windshields is a blast. Driving without mirrors...not so much.

Bulk update for the past weeks of "What did I do..." Truck's still apart, coming up on a month now, but it's pretty close to being back together. Maybe all done this weekend. Here's how things were looking... Transmission was nasty. I bought myself a pressure washer at some point and zapped this clean. I can't believe don't have a pic of the cleaned unit with the 4:1 case installed. I did do this, though... Maybe it'll make for a nice junkyard find one day! Cleaned out the underbelly! What a mess. Was loaded with Sedona red clay. You can't see it, but I also sheared a flex plate bolt at the 6 o'clock position. That sucked to extract. I had intentions to replace the RMS, but like many people have discovered, it's not the seal, but the stupid gasket strip of the seal bracket. After reading up on what all it actually entailed, I said screw it. Cleaned up the area and laid down some gasket maker all over it. Should be fine/I'll regret it some other day. I did pull down the lower oil pan to clean up all the oil build-up over the years. Everything's way cleaner now. Once I had the transmission attached, I changed out the motor mounts. Almost didn't because of how terrible access is on the passenger side, but I'm glad I did... Installed a transmission cooler... Ran into a snag with some crappy catalytic converters off ebay last weeked...they absolutely do not fit the truck. After numerous failed fitment attempts, I eventually built a jig with the OE assemblies and fitted the new stuff into the jig to see how bad was and maybe if it could be reworked...nope. It's terribly misaligned, practically every component of it. The amount of incompetency feels deliberate. OE units jigged up: New units on the jigs. Holy gaps/alignment/crap! Since the upper cats weren't marked L/R, I tried every combination and rotation possible. What you see is the "best" combination, and also the only one that was close to being feasible. At this point, I'm just planning to clean up the OE units and put them back on. I'm past the return date, so these are a loss likely. Not even worth the effort to rework; the catalytic honeycombs are probably crap anyway. The OE units are probably still fine, but this main overhaul was just to totally refresh everything, since I kept throwing a P0430 (catalytic converter efficiency) over the years. The upstream O2 sensors were the original sensors, and judging by their condition, it may be the real cause of the code. L to R: LH & RH upstream (both OE), LH & RH downstream (both aftermarket). I don't blame the previous owner for never changing them. They're such a pain. The heat shields alone probably added an hour to the job, because they block the sensor hex. I still need to get the cats and a new exhaust on...hopefully no surprises there. The other day I also realized that t-case shifter arm is different between an R50 and a WD22 Xterra, which is what my donor t-case came from. The Xterra arm is longer, which prevented shifting into 2H. Swapping the arms was a bit of a pain...the pins that hold the arm onto the shaft are wedged in place. Took penetrant, heat, and a hammer and punch to get it out. I was able to get them swapped tonight, so shifting operations are back to normal.