Slartibartfast

If the idle's steady, it makes sense that the timing would be, too. So long as it changes when load changes I'd assume that's how it's supposed to be. It was probably all over the place before because the computer was trying to make sense of the failed regulator barfing fuel through the vac line. I had an intermittent stalling issue with my '93 a while ago where it would stall out while stopped or coming to a stop, but only when warmed up (probably due to lower idle when warm). It was intermittent enough to be a pain to track down. Sometimes just turning the truck off and on again would clear it up, other times wiggling various plug seemed to do it, but then it got bad enough that I could barely drive it. I noticed that the plug for one of the idle air components felt a little loose, so I cleaned it up a little and squished the female pins so they'd be tighter on the male pins. It hasn't acted up since!

Unless something else on the truck is grounded to the frame, I wouldn't worry about it.

I think I found the binding in my front end, and it's not the centerlink. I removed the centerlink to check if it was bent or something, turned the steering, and found that it still bound up like crazy towards the middle even with nothing attached to it. Then I remembered that I read a Beer Garage writeup on adjusting that box and had a go at it at the same time as I put the centerlink in. I didn't adjust it very far, and if felt alright when I tested it then, but apparently the box didn't appreciate it. Backing it off to where it started doesn't help, and even backing it way off only slightly lessens the binding, which is not a good sign. After looking at the exploded diagrams in the manual, I'm not sure that adjuster even had anything to do with steering slop in the first place. So, yeah, apparently I'm a dumbass and I roached my steering box. Anyone recommend one reman over another?

Hmm. And it doesn't do this if the aircon is off? I wonder if the compressor's engaging while you're trying to start the engine. Is it turning over slowly before starting or turning over normally but taking a while to catch?

IIRC the last two years of the R50 had drive by wire. My dad's '03 did. It was one of the things I didn't like about that truck. I had a look at the FSM and the short answer is to try what Citron said. The sensor's got two separate pots in it, presumably so they can't both fail at once, and they're wired straight to the plug so that you can actually test them. Unhelpfully, the manual does not list their resistance, only their voltage outputs with the key on, engine off, MT in first or AT in D (no idea why). The first pot has two blue wires and a black/red wire, the second has a white with red, a red, and another blue wire (was there a sale on blue wire?). Sensor 1 (one of the blue wires, the one that's not steady 0v or 5v) should be 0.5 to 1v (measure its voltage to body ground, not to one of the 0v wires, apparently the ECU doesn't like that) with the pedal released, 3.9 to 4.7v with it floored, and sensor 2 (the red wire) should be 0.15 to 0.6v released and 1.95 to 2.4v floored. The graph shows straight lines, so yeah, if one of them drops out or bounces around then you've found your problem. Looks like you can also check all of this through OBD live data (SEN1 , SEN 2, and CLSD THL POS), but the ECU tweaks the numbers on one of them for some reason. If you do replace the sensor, the manual says to do three (!) different relearn procedures afterwards. All this starts on EC-708 of the '03 manual. I'd want to see if the sensor can be disassembled and cleaned. Maybe there's just some schmutz in there that a wiper's riding up on, and a shot of contact cleaner would resolve the problem without having to teach the computer how to tie its shoes again afterwards. Good luck!

If the splices are done properly, the rest of the circuit shouldn't even know they're there. Make sure you waterproof them. I use shrink wrap that's got some sort of hot glue stuff inside that melts and seals the joint when you shrink the tubing.

It's more drivable than it was, but that ain't saying much. The pedal thump is still there, but it doesn't seem to be impacting braking performance, so it's low on my list for the moment. The tires are shot (sidewall cracks), but I don't want to put the new ones on until I've got it aligned, and I can't get it aligned until I figure out why the steering's been bound up like the wheels are hub deep in wet concrete since I installed the Grassroots link. The front end refresh that was supposed to take a weekend has pretty well killed my summer.

If I'm reading this right: the truck shut off four times on your way home, but started again when you jumped it off another vehicle. Now it cranks, but will not start, and has no spark. Right? The jumpstarting suggests a charging system failure. If the alt died, a few lights on the dash should've come on. I'm at a loss for how that would've killed your spark. Definitely follow that amp power wire to where it's hooked up (hopefully it's hooked up at the battery) and unhook it so you don't have a live wire bouncing around. I don't know why someone would've connected an amp power lead to the factory wiring, but if they did, it could've blown fuses or even fusible links. Check the fuses in the box by your left knee and see if the fuse links on the battery + terminal are intact. There's a position sensor built into the distributor (pretty sure that's what SpecialWarr was talking about) that does tend to go out. If you crank the engine for a few seconds and then check the codes (instructions here), and the ECU didn't get the signal it expected, it should throw a code. Another thing to check: remove the distributor cap, have someone crank it, and see if the rotor's spinning. If the rotor's not spinning when the crank spins, the timing belt has failed--bad news because these things are interference. Good to rule out, especially given its lack of maintenance (who knows if the belt was done when it should've been). The factory service manuals used to be available through the Nico Club forum, but aren't anymore. There's a link in this thread to a source that worked the last time I tried it. I'd start with the EF&EC section.

I've read about the Sentras doing that. I've also read that some of the VQs suffered from excessive bore taper for some reason. I'd be interested to see what the bores in the junk engine look like.

Thanks guys. Yeah, there's an adjustment on the pushrod. I think I've got it about right but will look into it again--I've messed with it quite a bit over the course of this mess so it's entirely possible I've got it set wrong. Even if it was loose, though, I'd expect it to take up the slack before the brakes engaged, not halfway through the throw. My dad noted that the master cylinder itself moves a fair bit under braking force. It doesn't look like the firewall's moving, it looks like the booster is flexing. Having torn the old booster apart I know there's nothing inside that would stop this. I doubt this has anything to do with the weird thump but I do wonder if the pedal would firm up any if I made some kind of brace for it. I did a little research and found a bunch of Miata guys bolting little brackets to their strut mounts with feet pushing back against the end of the master. Kinda funny looking but apparently it improves brake feel. I might have to try something like that at some point... you know, for all the autocrossing I do with this truck. Also I know for sure now that my rear brakes are working! I can lock up all four on dry pavement. The rear end likes to step sideways when it locks, so I'll definitely be dialing that prop valve back down a bit. I'm still unclear as to what was wrong with the rear circuit originally. Best I can work out is that I had a bubble holed up in a crevice of one of the fittings I took apart when I was pressure testing the rear circuit.

Damn, that sucks. I haven't done valve seals on anything so I'm no help there. Can you compare to the seals on the buggered heads? Valves look good!

Wow! Looks like that cam bearing got good and hot before the camshaft gave up. Oil starvation sounds likely to me given the VQ's reputation as an oil burner. My dad didn't know his '03 burned oil until it got noisy shortly after he bought it. Maybe the same happened to the PO of yours, except they didn't catch it in time. Good to see that the rest of it's in better shape! My dad's '03 had the dark-colored engine bay, too. I figured it was primer and Nissan had saved a few bucks per unit by not spraying the engine bay body color.

The diagram of the oil pan on EM-16 in the '03 service manual shows RTV silicone (the GI section suggests Permatex Ultra Grey 82194, among other things) and no gasket.

Looks like you've got a good start on it! What was the cause of death for the engine?

I checked fluid pressures at the passenger's front and driver's rear tonight. Both are getting good pressure (I can max out the 1500 psi gauge on either). The bump persists. If the bump was due to one of the pistons bottoming out, I'd expect to still have a dead circuit, or at least see the pressure in one circuit stay flat when I push the pedal beyond the bump point, and neither circuit does that. I'm starting to think this isn't a hydraulic issue. My suspicion at this point is that what I'm feeling is the input and output rods in the booster bumping together. When I first push the pedal, the input rod moves, moving the air valve that dumps air from the footwell into the rear chamber of the booster and moves the output rod. The vacuum can only push so hard and so far, though, after which the input and output rods meet (bump) and I can push the brakes a little more manually. This would explain why it only bumps when the engine is running; with the engine off, the bump just feels like play in the linkage at the start of the pedal's travel. WD21 guys: if you press your brake pedal, slowly, as far as you can (engine running), do you get a bump towards the end? I don't think mine used to do this but I'm not sure I ever jumped on the brakes hard enough to find out... I didn't pay that much attention to the pedal feel until something went wrong.

I think so? It's been long enough that my frame of reference is kinda shot. It doesn't knock against the floor but it's definitely softer than I'd like. It feels about right after it hits where it goes bump.

That must be nice. I bench-bled the master again, reinstalled, and power-bled all four corners. The rear brakes do appear to work (haven't tried it back on the ground yet), but I still get a thump halfway through pedal travel where the pedal builds a lot more resistance suddenly, but only when the engine is running. My theory when the rears didn't work was that this was due to the secondary piston bottoming out in the master. Now that the rears appear to be working, and the pedal is still doing the same thing, I don't know what the hell is going on. Maybe it's the front circuit, but that doesn't make much sense given how easily it was locking up the front brakes before. I'm confused and I'm sick of this.

Looks like you found the squealing noise! I think those heads will clean up, and it sounds like they're in much better shape than the clean ones. Maybe the brownie crumbs on the pickup are the crud that got washed out of the heads? It looks a little milky in the crevices, though, so maybe coolant had something to do with it.. Good to hear your bottom end bearings are alright on the new motor. I've read that overheating can cause buildup on valves. Maybe that's got something to do with the white crap?

This head gasket thing had better not be catching!

Not much to go on. I'd check fuel pressure if you've got a gauge handy. Codes?

I think even the 4-banger trucks had electronic ignition here. I'm not familiar with Nissan's points dizzy wiring, but I'd be curious to see how the ballast resistor is connected. My understanding is that the points and coil get full battery voltage when the starter is engaged, but once it's running, power is re-routed through the ballast resistor to reduce the voltage to the coil (reducing load on the points and making the coil run cooler). If the coil gets full battery voltage all the time, you burn out the points or overheat the coil. Check the voltage from your coil + terminal to ground with the key on. I'm not sure why the dizzy would have an extra ground wire. Maybe Nissan didn't trust the connection between the head the dizzy for ground, and worried current would go through the bearings? Or needed a convenient engine ground for something else? The only points vehicle I have much experience with is the family snowplow ('63 IH Scout). They worked alright, but we ended up swapping them out for a Pertronix solid-state so we'd have one less thing to check when it wouldn't run right.

That explains the oddball I saw on the FB page a while back! Thanks for clearing that up.

Wow! Doesn't look like that saw a lot of oil changes. Good idea to check the bottom end bearings. Hopefully they're in better shape than the top end was.

I'd be surprised if you could tighten a timing belt enough to do that without something else failing first. Looking back at your earlier pictures it looks like it's not just the bearing that's cracked, it's the head casting it's pressed into. Good thing you've got the other set of heads on hand! I wonder if that crack was letting something (combustion gasses? Coolant?) into the head and causing the sludge buildup you found there.

The trucks with the ATX14A have a heater knob looking deal on the dash to control the transfer. I assume hi/lo is just a servo controlled by the transfer case computer. The TX10A trucks have the lever through the floor. You'll have to do some bodging on whatever actuator you go with--AFAIK there was never a factory electronically controlled TX10A, so you're looking at some custom work to get something mounted up and then to figure out how to control it so it stops in the right places. As for the pictures, unfortunately the only way to get bigger pics is to host elsewhere and embed or link them.