Slartibartfast

Welcome back! I imagine the axles would be pretty quick and easy for a shop to replace. They're not too bad to do yourself, but the bolts holding them to the front diff are 12mm 12-point, so make sure you have a 12-point impact socket before you get into it. I rebooted my old axles and swore I'd never do it again--there must be some trick to getting them apart that I didn't know, because good lord those things fought me. I've read that the OE axles are usually better than whatever reman crap is out there, but after the time and aggravation of re-booting, I might roll those dice. Looks like you highlighted the sway bar end link (very easy, probably needs the bushing that holds the swaybar to the frame too), upper and lower ball joint (not too bad, thankfully Nissan didn't rivet them in like some makes do) and tie rod end (also easy). It'll need an alignment afterwards, so any other front end work it needs, you might as well do at the same time. If you haven't done the strut rod bushings yet, they're probably due too, and may require some welding.

I think they were Timken L68111. They weren't perfect, but they were close enough. And, yes, weld-on. Weld it good and hot, there's a lot of carbon in that bearing steel.

AFAIK any mid '93-'95 (round dash, pre-airbag) D21 should have the same wheel as yours. A really low-trim one might not have the cruise control buttons, so watch out for that. I would avoid the '96/'97 D21 wheel with the airbag. I imagine the splines in the airbag wheels are the same, but they've got a clock spring instead of the sliding contacts, so you'd have to do some screwing around to get the horn and cruise control buttons working. And then of course there's the 26-year-old pyrotechnic device in the middle of it. I'll second Adam's idea--check out other pre-airbag Nissans of similar vintage. I looked up a '94 Maxima wheel and it looks like it's got the same cruise buttons, so that's promising. Couldn't find a picture from the back, but if that's the same, it may bolt right up. The trick is finding one in better condition than what you've got now. If you try to pull the wheel off its splines without a puller, thread the nut back on a few turns before reefing on it so you don't slam it into your face when it lets go.

Hopefully that's got it and the trans settles down. If it keeps acting weird, check the fluid level, at operating temp, in neutral, engine running. It's a pain to get set dead nuts on, but too high or too low can make it act up.

The manual VQ R50 is kind of a rare bird, so you may have some difficulty sourcing parts. Last I heard new flywheels weren't available. The service manual does show some minor differences between TX10A (manually shifted) transfers for auto or manual trucks. The manual version has a lip under the input shaft seal and a couple of bits internally that I don't know the purpose of, and that aren't present in earlier manuals. AFAIK the auto version will bolt to a manual transmission without issue. If it's got the ATX14a transfer case (knob on the dash), looks like they only made one version of that. I have no idea if that box was even offered with the five-speed. If that's the one you've got, I would check the wiring in the service manual to make sure it's not relying on the auto trans computer for something. AFAIK the driveshafts are the same, but don't quote me on that. No idea on the computer or power valves, sorry. RE your other post, sounds like you know most of the issues with the VQ. I would also inspect the front strut towers. They rot out badly enough that there was a recall in some states, and Nissan "fixed" some of them in an alarmingly half-assed manner.

I removed a set of brackets from a WD21 and ended up cutting it up like you did on your donor, and even then there was some screwing around involved. Hopefully there's a little more room in the R50 quarter panel.

If you can fit the whole bracket in there, just use the nuts on the bracket instead of the riv nuts. The riv nuts are just a way to avoid having to deal with the brackets. Maybe you could remove the nuts and use the riv nuts to hold the brackets to the panel--but I would expect that to be a PITA to line up, and also weaker when you're done, and I don't know if there's enough length on the riv nuts to clamp through the bracket and still hold themselves in. From what I remember (and can see in the picture), that truck has great big honking tires on it, so any strength you can add to the tire carrier mounts will be a good thing.

Ouch. Headlight sure looks tweaked in the last shot. Might've just popped the ball out of the bracket. The grille might be alright, or at least salvageable. Super glue worked pretty well on the grille for my '95. Works great reinforced with baking soda. I used sawdust, don't remember why, but that also worked. Bumper's junk, bumper brackets probably are too. You won't know more until you start pulling it apart. Hopefully it doesn't take much to bring it around, looks like a really clean rig otherwise. When I hit a deer a few years ago, I figured the insurance would want to junk it/be more hassle than it was worth. I just put a strap around the bumper and pulled it straight enough. The rad support needed a little tweaking to get the fender to sit flat, but a couple hours' work got it close enough. One of these days I want to build a stronger bumper, so I didn't bother getting it perfect, but unless you squat down and really look at it, it doesn't show. Hopefully injuries in the Honda weren't too bad. That sounds like a recipe for whiplash.

Some options are pre-wired on these, and the '87 manual shows power mirrors as an option. I'd be curious to check behind the dash and the mirrors see if the pigtails are there already. If they are, it should be an easy upgrade. Otherwise you may need to run some wires. I would not be surprised if the power mirror pigtails were part of the harness for the power locks and windows, so if you don't have those, but the dash is pre-wired, you could get door harnesses from a higher-trim donor and make it work that way. If you have to recreate the harness from scratch, it looks like a reasonably simple system. There's a wiring diagram for it on BF-43 in the '87 manual, or BF-45 of the '89 (which I have on dropbox here). Might need to find the wiring for the rear defroster if you want to get the heaters working.

I'm not sure what the factory used. The service manual calls for their KP610-00250 sealant "or equivalent." The description on NissanPartsDeal says "gasket-liquid," which does sound like Hylomar, but it also says FIP, which I assume is form-in-place, which has me thinking silicone. Let us know what you find when you tear it down! I would expect either type of sealant to do the job provided it's applied properly and the mating surfaces are clean. Unless I had a good reason to use something else, I would use black RTV. Seals are a good idea while you're in there. A seal that isn't leaking yet may change its mind after being disturbed. My front crank seal did that after a timing belt change. I haven't opened one of these transfers, or dropped one on its own, so I don't have much in the way of specific tips. The shift linkage is removable, that might save you some trouble. If you drop the whole transfer case, a transmission jack will make your life much easier. You may need another jack to support the back of the transmission while the transfer is out. I would be tempted to try and remove the back case half without removing the rest of the transfer from the truck, if there's clearance for that vs the torsion bar crossmember. If you need to remove that crossmember, 1) make damn sure the front end is on jackstands first (the torsion bars hold the front end up) and 2) mark or take a picture of the adjusters before taking them apart. They're a bit fiddly to adjust, so having their starting position marked in some way will save you some time trying to trial-and-error it back to where it was. Oh, and you'll need some way of getting oil back into it when you're done. A hand pump will do, slowly. I fabricobbled a jar with a hose and an air chuck to make it easier. When a friend and I dropped the transfer from an Exploder a while back, we overfilled it, installed it, then removed the fill plug to drain the excess. Worked great.

Could be the driver circuits for those LEDs are spitting noise back into the electrical system, and your radio is picking that up. If you swap in standard bulbs and the issue goes away, that would confirm your suspicion.

Thanks for closing the loop! Nice when it's an easy fix.

Those do look like they might work. The only issue I see with them is that the diodes are facing straight in, and in both cases they need to be facing 90° out to light up the button face properly.

Could be a small injector leak flooding the intake with fuel vapor (which dissipates or leaks past the rings when it sits overnight). On your next warm start, try flooring it while you're cranking. That should put it in clear-flood mode (injectors off). If it's flooded, it should fire faster like that than it does normally (clears out the flooding faster when it isn't spraying more fuel on top of it). You could also do a fuel pressure leakdown test (hook up a fuel pressure gauge, prime the fuel system, see how long it takes to leak down). Also check your oil--does it smell like fuel?

I checked the hazard switch from my 6/'95 parts truck, and it has the same quarter-turn light socket as the aircon switch, right there on the top. If your '94 doesn't have that, it must've changed somewhere in between. The D21 was available in the US until 7/'97, so the socketed version should be easy enough to track down--or PM me, I have no use for the one I've got. That said, these are not that tough to open up, and if you do it right, you'll only have to do it once. Even if you get the socketed one, I would still solder the resistor and LED to the circuit board instead of trying to work around the socket. That could be done without opening up the switch. The bulbs in the sockets appear to be the same ones used in the rocker switches. And, yeah, they're not 74s; reading that link I posted properly this time says it's the HVAC head unit that takes 74s, not the switch.

It's a little fiddly, but honestly not that bad, apart from the pucker factor of working with 30-year-old plastic that needs to go back together when you're done or something on the truck won't work. And yeah, the marker light circuit lights up the front corner lights and the tail lights. I've got an aircon switch in my spares bin that I might have a poke at later if I remember to. I would be tempted to solder the resistor and LED directly to the contacts on the circuit board rather than try and re-use that little bulb holder. Nice that you can get to it without separating the housing, though. I forgot about the latching push-style hazard switches in the round dash. Looked one up on eBay and, yeah, looks like they've got the same screw-in bulb housing, so that's nice. Does the switch on your '94 not have that?

Looks like the rear ball joints are retained by a snap ring, so if you can find parts, it should be possible to swap them out. Unfortunately I'm only seeing separate bushings and joints listed for the front end on Rockauto, and whole arms only on nissanpartsdeal (the exploded diagram shows the arms with the joints/bushings installed). No idea if they match the fronts, or any other vehicle. You could compare bushing size vs your front end to see if they're in the right ballpark. Maybe pick up a set of used arms from a wrecking yard? If they're not better than what you've got, you could take them apart, get dimensions, and see if you can find joints and bushings that'll fit before you tear your truck apart. There aren't many active R51 owners on here, so you may find more info elsewhere. Good luck!

It's simpler than that. The dash illumination circuit supplies about 12v, which is what the incandescent bulbs were built for. The component LEDs I'm using in the switches want about 3v. Wiring a resistor in series with the LED limits current, which drops the voltage across the LED. Without the resistor, the LED would burn out as soon as it got power. I did not install resistors in parallel (like the Canbus bulbs do to simulate incandescent bulbs for fussier applications), and the switches do not illuminate when they shouldn't. There's no bulb monitoring going on in this circuit, and AFAIK there's nothing tricky that relies on them working like standard incandescents. The dash illumination circuit taps into the marker light circuit, so when the headlight switch is off, the dash illumination should be completely dead. AFAIK the only other components that could be supplying power are the alarm (taps into the parking light circuit so it can blink the lights when it does stuff) and the stereo (connects to dash illumination, I assume so it can dim the display at night). I would be surprised and concerned if either was leaking enough current to light up the switches, much less the switches, the cluster, and the marker lights, because, again, they all share a + feed--though at a low voltage, they may not all light up. (The dash lights ground through the dimmer switch.) That said, I have standard incandescents in my marker lights and my cluster illumination, so any stray current would have plenty of available paths to ground. If you swap every bulb on that circuit for LEDs, and end up with a ghost glow on the dash, I'll bet a couple of incandescent or Canbus-friendly LED bulbs in the front corner lights or the tail lights would sort it out. Looks like the aircon switch takes a #74 bulb.

I'm all about keeping stuff going, but between the structural rust, the rod knock, and all the other stuff you mentioned, it may be time to take that one out back.

Have someone work the wheel while you lay in front of the truck and have a listen. Maybe grab a few things and see if you can find the pop by feel. Might be something loose, might be a dry joint binding. I'm not familiar with the strut tops, but I'd check those, too. Hopefully it's something you can tighten or shoot some grease into, not something that'll need another alignment after you fix it.

You do have to take the switches apart to get to the bulbs. The bulbs themselves are tiny little buggers, about the size you'd find in a model train, with the leads wrapped around a rubber block that sticks onto some metal posts. I have converted all but two of mine (the two I can't reach without pulling the dash) to LED by removing the dead bulbs, and the rubber block, and soldering resistors and LEDs in their place. It's a bit tricky, and the switches are fragile, but it is possible. Separate the switch in the middle, where it's snapped together. This will take some screwing around to get all the snaps released at the same time. Don't try to remove the rocker on its own, you'll break the tabs it pivots on. Once it's apart, you'll see the incandescent bulb, which has a blue rubber condom over it. Work out the polarity (look at the plug--pink/blue is +, pink/black is -) and mark it so you don't solder stuff backwards. Work out how much of the metal tabs you'll need to cut to make room, so you can get the LED in the same place, with the bulb aimed at the rocker. This may take a little screwing around to get the LED where you want it and not interfering with anything else. I use 1k resistors and 3mm warm white LEDs. Test that the LED works before reassembling the switch, and make sure the rocker engages the sliding part properly when snapping it back together. IIRC there's a little ball and a spring that makes the rocker latch or pop back (depending on the switch), which may fall out when you separate the switch, so keep an eye out for those and make sure it all goes back together how you found it. One of these days I'm going to take my dash out again, and when I do, I'll convert those last two switches, and make a writeup or a short video on how it's done. Naturally this is not that day.

Check for any obvious damage to the OBDII plug, its pins, or its harness. Worst case you could check the wiring in the EL section of the service manual (free here) and check each wire. If there's damage somewhere, my bet would be the plug itself, unless someone's been playing around with the wiring. If that fails, the AT section of the manual has instructions for decoding the flashes without a scanner.

Good work tracking it down! I like the Arduino scope, that's clever. I've heard of the gear on the sensor breaking, but the one in the transfer going is a new one on me. I haven't been into one, but it doesn't look like it would be terrible to get to, apart from the fun of working over your head on something that wants to leak fluids on you. Nissanpartsdeal lists what I think is the right part. The case is sealed with silicone, not gaskets, so at least you don't have to try and keep a gasket in place while you line stuff up. If both gears are worn, but not broken/chewed up, I would be tempted to replace just the one on the sensor, to see if that gave it enough engagement to work again. It's not like it's transmitting a whole lot of torque, right? Posting pictures here usually means hosting them elsewhere, unfortunately.

It's easy to forget about the diffs. They don't need attention very often, so they get put off and forgotten about. For the most part, they seem to hold up alright anyway, so long as the oil doesn't leak out, water doesn't leak in, and you don't beat the hell out of them. Like most things, the diff will probably last longer and run better if you keep good lube in it, but it's not gonna turn into the other kind of pumpkin if you don't adhere to the schedule exactly. Reminds me, I should change the oil in my front diff at some point. For all I know, it's been in there since the truck left Kyushu.

+1 for checking connectors and giving the computer a time out. I've got a loose MAF plug on my MPFI that makes it surge and stall when it acts up. I would also re-check the vacuum lines around where you were working. I have not worked with the TBI, but I've heard it can be pretty finicky, including running poorly with the air cleaner off. I don't have a PDF of the '87 manual, but I've got a PDF of the '89 up on Dropbox, and the TBI system is the same between those years AFAIK with the exception of some codes that got moved to different numbers, just to be difficult. (The '87 lists 42 as TPS, 43 as injector circuit, and 44 as no malfunction; all the other manuals I've got lists 43 as TPS, 51 as injector circuit, and 55 as no malfunction. The coolant temp sensor code did not change, so, no worries there.) The EF&EC section of that manual can tell you more about the TBI than I can. If you run into something in the '89 manual that doesn't match what you're seeing, message me, I've got a paper copy of the '87 and can cross-check if you want.