Slartibartfast

White smoke and one dead hole sure sounds like a head gasket issue to me. +1 on the leakdown test to tell you for sure. And +1 for doing the timing belt etc while you're in there. Cam seals, crank seal, bypass hose, belt, tensioner, pump. I skipped the crank seal the first time I did mine, and naturally it started leaking the moment I had it back together.

Maybe you got the early 27 spline hubs? The hubs and CVs switched to 28 spline between '89 and '90. Don't think I've ever seen a Ridge Line hub. Hopefully that's the last speed bump to it going back together!

Spark but no fire on carb cleaner suggests it's either massively flooded, or the timing is way off. Do you have a timing light? The ignition timing should not have changed if you haven't moved the distributor, assuming everything's as it should be behind the timing cover. I'm also assuming the last guy had it set up properly, given it ran before you opened it up. Confirm that you've got 40 teeth between cam dimples, 43 cam to crank. If you had the sprockets off to do the cam seals, confirm that you reinstalled the sprockets on the correct sides. Left and right are marked from the driver's perspective, not the mechanic's. I've never had an issue with it, though I have heard of people washing the oil off the cylinder walls by using too much. Some starting fluid has oil in it, that's probably better for extended use if you have to run it on spray. I mostly just use it to make sure a small engine's worth buying a carburetor for. I don't know if it's the ether or the stuff they add to stop people from huffing it, but starting fluid gives me a headache real quick. Not that carb cleaner is healthy, but it doesn't hit me like that. I see guys on Youtube using brake cleaner, and they seem to get away with it, but I don't want to know what's coming out the tailpipe when that stuff burns!

Towing 5k lbs with an out-of-warranty CVT seems sketchy to me. Looks like some people do it, though. Do some research on what they do to keep them alive. Fresh fluid and a cooler might help. Looks like load distributing hitches are a thing for these, probably a good idea if you're cutting it close on the tow capacity. I've never driven an R52, but I'd expect the VQ to get up and go pretty well. My dad's '03 had an earlier VQ, and it got up and went just fine. I imagine it would be screaming at you if it was in some kind of limp mode, though I would still check and see if it's got any trouble codes. I would also check that it isn't in some kind of eco mode that's nerfing the throttle response.

Looks like they've got the same lift as the VG30 cams, but a little more duration. Mr. 510 called them the best stock cams from the US market (or words to that effect) in his VG34 thread, so if a set happens to fall into your lap, I'd call that a win! This chart of stock cam specs shows the Z31 cams second only to the Euro cams, which again have the same lift, but a little more duration. Looks like the Euro cams moved the power band up just a little (traded a little low-end for a little high-end?), but nothing crazy.

Clean is a good start, but given their history, you should at least put a straightedge on them. The flatness spec (from EM-24 in the '97 manual) is 0.01mm (0.004"). Put a straightedge across the head (corner to corner, diagonal and parallel) and see if you can get a four thou feeler gauge in between anywhere. If the feeler fits, resurface or replace the head. Don't cut more than 0.02mm (0.008") off the head. If the cam doesn't spin freely in the head, because the head is warped to where the cam bearings don't line up anymore, replace the head. The difference in lobe height between the VG30 and VG33 is only around 0.3mm on the intake, 0.6mm on the exhaust. You're gonna need calipers to see that. Measure from the tip to the base circle on the far side (the full height of the egg, if that makes sense). The '95 manual says the VG30 lobes (intake and exhaust) should be 39.537 to 39.727mm. The '97 manual says the VG33 lobes should be 39.242 to 39.432 on the intake, 38.943 to 39.133 on the exhaust.

I've never worked with the 2WD parts, but I had a look at the parts diagrams on NissanPartsDeal, hoping to see the same part number between them. Instead I found six of them. 4WD shows 40202-0W094, 40202-0W091, and 40202-0W092. 2WD shows 40202-1W091, 40202-1W092, and 40202-1W094. Naturally I have no idea what's different between those six part numbers, or if it's significant enough to stop one from fitting the other. If you can't find a used one, NPD does have one of the 2WD part numbers still available. Punch in your info and see if they reckon it'll fit.

This TSB. The 190 tstat that the TSB says not to use was for unspecified earlier models. I have no idea why Motorad is listing one for VG applications now. Maybe there's a demand from people who don't know how the cooling system works. Or maybe the increase in heat across the engine is not as high as Nissan expected, as seems to be the case with yours. (Or maybe the increase the TSB is talking about is more of a worst-case-scenario, assuming hard use in hot weather.) Everything I've checked says the VG R50s ran 180 tstats. The '97 R50 FSM specs a 180. This listing shows a 180F/82C tstat as fitting '98-'04 Fronty (w/o supercharger), '00-'04 X (w/o super), '96-'01 R50, '93-'01 Quest, and '89-'94 Maxima. The TSB above says to use the 180 from a Quest or a Maxima, which makes sense, as those are the only vehicles on that list that were in production when the TSB was written in '94. How are you logging your temps?

Good work. Annoying that it doesn't know what's up, but that's OBD1 for you! You can test it with a plug, yes. I use an old spark plug for this so I don't have to take the existing plug out. I like doing it that way because it makes it harder to zap myself. When I don't have a plug handy, I stick a screwdriver where the plug would go, hold it by the plastic handle, and hold the shank maybe a quarter inch from the manifold while cranking. Otherwise you can just hold the wire (by the insulation!) so there's maybe a quarter inch spark gap between the intake and the end of the wire. This is easier with the coil wire. Speaking of zapping yourself, I haven't heard of anyone being properly injured by it, but that doesn't mean it's a good time. The ignition system should be putting out something like 28,000V. Be careful where you put your fingers, and don't hold onto a damaged wire. You could also start with the carb cleaner if you're more comfortable with that. If it kicks on spray, then you know it has spark, and you can skip messing with the plug wires.

I'm 90% sure I put a 170 in my VG30 when I had it apart. I have noticed it struggling to hit temp when it's real cold out, but I think I remember it doing better when the tstat was new, so it might just be aftermarket junk that's on its way out out after 30k miles. I bought a 180 tstat from Nissan for the VG33 to see what that does. It'll probably be summer by the time I get that engine in the truck, so I'll know pretty quick if 180 was a mistake.

I just stumbled across some info on the 190F thermostat. It does exist, but Nissan warns of cats and dogs living together if it's used in a VG. The problem with the 190F thermostat is that the VG does not run at the temperature of its thermostat. The VG's thermostat is located on the lower rad hose, the cold end of the system, so the engine actually runs 10-15C hotter than its thermostat. Nissan's target for max engine temp is 90C (194F). 76.5C (170F) plus 15C is right on target at 91C. 82C (180F) plus 15C is pushing it at 97C, but apparently Nissan was comfortable with this, because NTB94-020 recommends swapping in a 180F thermostat to help the heater keep up with winters on Hoth (like Adam did), and (as Adam noted) they later spec'd 180F thermostats for the VG33E. 88C (190F) plus 15C is 103C, and apparently that's out of Nissan's comfort zone, because they warn that it could cause overheating, detonation, engine damage, computer trouble, and a voided warranty. The 190 thermostat was used in earlier (pre-VG) Nissan engines. They had the same 90C/194F max temp target, but their thermostats were on the upper rad hose, so they didn't have that 10-15C offset to factor in. TL;DR: 170 is stock, 180 is OK, and 190 is not recommended.

Sorry to hear the computer is clueless as usual. Did you check after a failed start? I think it's supposed to hold onto codes for a certain number of starts, but I don't remember that for sure. An ignition issue on one cylinder shouldn't impact the other five. If you didn't pull the dizzy, and the tooth count between cams and cam/crank is correct (and it was when you started), then it shouldn't be timing. If you messed with the plug wires, confirm that they all went back where they're supposed to. I wouldn't expect the cap/rotor to suddenly and completely die, but given you had the cap off, I would pull it and just make sure it's not wet inside and the rotor is present (you didn't remove it to clean it and forget to put it back) and correct (mounting bolt hasn't fallen out or something). Other than that, we're back to checking for spark and fuel. If you're sure it's getting fuel past the injectors, pull a plug wire, crank it, confirm that you have spark. If you don't, check at the coil wire to see if the cap/rotor are the problem. If you have spark, but aren't sure fuel's getting past the injectors, spray some carb cleaner or starting fluid into the intake. If it runs when you spray fuel at it, then you know it's a fuel issue.

I wonder whether the benefit from those is from the new/different modes, or more from overriding whatever "optimization" the ECU does. I've been annoyed by that meddling in almost every E-throttle vehicle I've driven. Small adjustments ignored, smooth inputs made jerky. I much prefer the cable throttle in my '93. The old VG30 may be gutless, but at least it tries to do what I'm asking!

Depending on the calibration of your torque wrench, you may have gotten it perfect!

Looks like progress! Bet that manifold leak was noisy. If it was blowing hoses from exhaust gas getting into the cooling system, that suggests you were right about the head gaskets. Check for cracks and warpage while it's apart. The oil in the valley probably came from the valve cover gaskets. That depends on how far you go. The VG30 and VG33 service manuals have identical specs for the valve springs, so the stock springs should handle VG30 cams just fine. JWT even recommends the stock springs with their S1 cams, which if post #7 in this thread is correct, are a larger jump in lift from the VG30 cams than the VG30 cams are from the VG33 cams. JWT's S2 cams do spec harder springs. And yeah, if you're pulling the heads apart anyway, that would be a great time to clean out the gunk and lap the valves. Mr. 510's VG34 thread has some info on porting if you want to give that a go.

AFAIK Teflon tape is fuel-resistant, but it's meant for tapered pipe thread. I haven't had a fuel pump out of an R50, but looking at pictures of them, I'm not seeing tapered pipe thread connections. I'm seeing hoses clamped to nipples and quick-connects, neither of which take Teflon tape. Generally quick-connects take O-rings. If the O-rings are bad, you could probably pick them out and install new O-rings. I remain skeptical of your vacuum theory.

I've heard of people rolling bearings into engines from underneath. Not sure I've heard of anyone doing it on a VG, but I don't see why it wouldn't work, provided the crank isn't beat to hell. I'm not sure fighting with it on your back with oil dripping in your eyes would end up being less work than pulling the engine, though.

I would expect a quick-connect that's loose enough to leak from being slightly tilted would be leaking bad enough to cause all kinds of other issues once the truck was driving around, going over bumps, going up hills, whatever. Manifold vacuum at idle is, what, 10 psi? And it would be pulling through tiny little injector orifices. The rail should be between 34 and 43 PSI. I don't think manifold vacuum is doing anything for the fuel system that the pump wouldn't, unless something is badly wrong with the pump--and again I wouldn't expect that to clear up once it was running. That said, air in the pump, or air pushing through the regulator, might explain the noise. The next time it acts up, try cycling the key a few times. (On, wait for the pump to stop, off, on again.) The pump should run for a few seconds each time. It's a return fuel system, so if the lines have somehow drained back into the tank while parked, this should prime them again. If it fires right up after cycling, or if it makes the weird noise while trying to prime, or if the pump doesn't run at all, then you know you're on the right track.

And here I thought it was Ford that only ran downhill. That is a weird one. I have no idea what in the fuel system would change with inclination like that. If the fuel level was really low, maybe the angle could make the fuel run away from the pickup--but if that was the case, it wouldn't keep running after it used up the ether. If you slowly rev the engine in park, can you find a speed where it makes the noise? I don't know the R50 computer, but I wouldn't be surprised if the computer was demanding a higher idle for a moment after a difficult start. If you can replicate the noise by revving it to a certain speed, might be an idler pulley on its way out, a loose heat shield, something like that. If you haven't pulled codes yet, do that first, on the off chance the computer knows something. If that doesn't help, check the fuel pressure. Try and get it to act up while you've got the gauge on it. Also see how fast the needle falls when you shut it off. Maybe a leaky injector is flooding it? Though again I wouldn't expect nose up/nose down to make a difference there, and I wouldn't expect throwing more fuel (ether) at it would bring it around. Intermittent issues like this can be a real pain to track down, because they tend to hide until you put the tools away. Good luck!

'95 manual says 72-80 lb/f for the flywheel bolts. For some reason it's in the "cylinder block" section. EM-36. Good luck with the case! Hopefully no surprises inside.

+1 on this. If you have all three, check timing, especially if you've had the distributor out. It's easy to install it at top dead exhaust instead of top dead compression. I've done that. Might also be worth running codes. The computers in these are not very perceptive, but you should get a code if it hasn't heard from the dizzy in however many seconds of cranking, or if there's no ignition pulse to the coil. Either way, that would give you a road map for what to check next.

Confirmed the size. 12mm 12 point.

Ah, gotcha. PM sent!

The one I borrowed had a U joint in it (I think it was this one, or very similar). The wobble was helpful. But I think I got an axle off the parts car with just a shallow socket and a separate impact-rated U joint.

I'll dig them out later and PM you a picture. How did it end up missing all four?