level9

Be careful and note torque settings in the FSM - it's very low. There's a reason they were simply Philips heads (cams out when too much torque applied). Overtightening can produce leaks. When I did mine I actually attached a Philips bit head to a torque wrench. Not the kind of job you want to do over - especially the driver side.

You can put UV dye in the oil, drive it for a bit then check with a blacklight if you must know definitively. If the gasket is bad and you are planning on keeping the car a good long while, you may as well replace both gaskets; however you'd probably want to go ahead and refresh the coolant, vacuum hoses and intake gaskets while you have the intake off if you have not done so already. Probably do the fuel pressure regulator as well.

I'm looking to get some new OEM seat belts for my '90 Pathfinder. Due to an interior color change, I'm looking to get the gray version (color code: K). My understanding is the earlier years (90-92?) the gray is more of a gray-brown whereas the later years (93+?) have more of a pure-gray. I'm looking to get the pure-gray version but does anyone know if the later years (94-95) seat belts would interchange with a '90 ? From the few pictures I can find online, the design appears different but it's hard to tell...

Pretty much what Citron said. EVAP you might want to delete if you want to free up engine bay space. Where the charcoal canister is located may be a good spot for a dual battery setup; however you still need to vent the tank fumes. If I were going to do this, I would probably unplug the EVAP line from the gas tank end and plug it with a small hose connected to a small filter and tuck it up under the chassis somewhere. Note, you might smell gas, especially on hot days as you approach your car. Probably wouldn't recommend this if you garage your car. Personally, I would keep the PCV system but would modify with a catch can between the PCV valve and rear pass. side valve cover breather. This keeps the junk out of the intake, but does require you to empty them on occasion. If you just want to delete it, you could cap the PCV side on the intake manifold, then cap the front breather port (the front of both valve covers are connected to a Y-pipe which connects to the intake boot), then route the rear pass side valve cover using 5/8" PCV/EEC rated hose to a small breather filter. Ideally, locate the filter somewhere you don't mind getting dirty as blowby (oil + gas) will be spewing out of it. Alternatively you can attach breathers to both ends instead of capping, but likely not necessary on our cars.

You might try one of the head gasket sealant products. If you are ready to toss the car, seems like you've got nothing to lose. Unfortunately (operational) WD21s are getting harder to find these days . Perhaps consider just doing the head gasket job or buying a JDM engine and swapping out? Low mileage JDMs are reasonably cheap and probably a better bet than buying another high mileage WD21. GL

According to the FSM (where you can find this info), just the EGR Temp Sensor was CA specific; however I also thought the EGRC-BPT valve was as well although the FSM does not read that way (maybe it was CA only in < 94 models and then became Fed standard). I am not sure if your CA ECU will CEL if you remove/disable temp sensor - something to keep in mind. In any case, if it is for off-road use only, why not just strip both CA and Fed equipment? AFAIK, only the cat converter is required both on and off road, but IANAL..

I had another thought since we were on the topic. You may want to start off checking/replacing the PCV valve first and see if that solves your issue. If it is severely plugged up this can contribute to oil leaks. Reason being, the crankcase pressurizes due to blowby and this can push oil out the older/weakened gaskets. The blowby will exit the wrong way - on the breather side (hoses connecting valve covers to intake boot). Evidence of a plugged PCV would be a lot of carbon buildup on the throttle body. GL

Yeah, I cleaned my PCV valve originally, shook it back and forth and it seemed fine. I saw how cheap the OEM one was and said what the hell and bought it anyway. I then compared the new OEM to the clean one and there was a quite noticeable difference in spring tension. So I just recommend replace now.. they will still mostly work once cleaned up but the after moving back and forth a zillion times over 10+ years, the spring just starts to wear out. This can sometimes contribute to increased oil consumption as you might not get quite the same/consistent level of crankcase vacuum which can hurt with ring sealing (increasing blowby, hurting fuel economy, etc.). Some cars are more sensitive than others. The use of low tension piston rings in later model years causes more problems with malfunctioning PCV systems.

Intake: Personally I don't like to use RTV here; although I'm sure plenty of people do it without issue. Reason being, the RTV will squeeze out into the intake runners and there's not much you can do about it. If you go this route, make sure you use O2 sensor safe RTV as bits and pieces will brake off over time and could foul sensors. With the intake off, it's a good opportunity to clean off the carbon buildup. I use a can of Seafoam with a flexible bottle brush like OXO Good Grips Bottle Brush to clean the intake runners. Then clean the idle control valve, EGR, throttle body and idle air bypass with CRC Throttle Body & Air Intake Cleaner. You might consider replacing your PCV valve while you are at it. Personally, I will only buy an OEM PCV valve and they are pretty cheap. Make sure to seal the threads on reinstallation with thread sealant (or O2 safe RTV would probably be fine here). Valve Covers: Be careful with removing the hoses from the tops of the valve covers unless you intend to replace them. This is part of the crankcase ventilation system and it is a special fuel/oil resistant rubber and at least the front, pass side valve cover hose would likely need to be replaced with OEM only version due to it being premolded with a very tight radius bend. Also the hose connected to the PCV on the intake is the same - premolded and I'm not sure you can bend an aftermarket hose into that radius. Before removing the distributor, mark the rotor position relative to the body with a marker. Then align it back on reinstallation. This should avoid the need to check timing as Citron mentioned; although it's never a bad idea to confirm. EDIT: Almost forgot.. you need to mark the timing adjustment bolt as well. I did not have to do this on mine as it left a very nice clean spot when I removed the bolt so it was obvious! During reinstallation, make sure to clean the surfaces and bolt the covers back down using the proper pattern as noted in the FSM. It is also recommended to torque to spec. As I recall, there is actually 2 different torque specs combined with the bolt pattern to effect a 'proper' installation; although plenty of people don't do this and have no issues, so it's up to you. Some people also use High Tack Gasket Sealant on the heads to lock the gasket in place and help prevent future leaks as added insurance. If you want to implement some performance mods while you are there I can also make some recommendations as well, but it's extra time and $$. Good luck!

If you want to boost efficiency, have already done all of the other mods/upgrades, want a fun project and happen to have money burning a hole in your pocket, then cover the roof with solar panels and wire it into the electrical system. This will reduce load on the alternator and thus mechanical drag and give you 'free' power. After generating ~750W from the solar, should be good for a solid one whole HP gain

I actually looked into this recently. Neat technology and might be a fun project. Do not expect any efficiency gains (actually you will likely lose some MPG) if you are generating HHO on the car. The power gains cannot be offset by the poor electrical conversion efficiency of the alternator (as I recall, 60% at best is typical).

Do you still read 14.4v with the car running and headlights, audio, etc. equipment turned on? A couple of grounds to check.. The main ground that runs from the battery to the passenger side fender to the block. I've found the fender ground connection to become corroded over time. Unbolt the ground from the fender, de-rust, scuff paint, bolt it back on and cover with Liquid Electrical Tape. The alternator ground: I believe it grounds at the upper radiator core support (black wire, driver side, near the hood prop).

Agreed, fronts should have gone out first. Just got the report and the fronts are 7mm and rears down to 4mm, so that can't be right... We hadn't noticed any braking issues other than the squeal from the rears just started up this week. Nissan had a TSB about ABS bugs we had patched a few months ago, so I guess I'm just going to chalk it up to that and replace the rears. On a positive note, the air filter is the same as the one in my WD21 so I was able to swap that out with an old K&N I had to save a few bucks

2013 Pathy w/ 25k miles. Up to date on all TSBs. Wife just took it in for an oil change so haven't had a chance to look yet. Dealer says the rear brakes are worn and already need the rotor machined!? For starters, it seems a little early to already need a brake job? Also, Dealer says front brakes are fine. Why did the rears go bad so fast? He blamed electronic braking control but sounds fishy to me...

Let's see.. paper thin sheet metal which will rust to dust in no time, heavy use of biodegradable plastics, extensive use of increasingly complex electronic everything whose capacitors and other parts will be dead as well as the programmers - who programmed it all with proprietary code. Honestly, I'd be surprised if most of today's cars survive long enough to become classics.