Captain Obvious

One of the rear wheel cylinders on my 77 280 was leaking a little so I bought rebuild kits for both sides. I've got kits from both Wagner and Tru-Torque, and the basic P/N is 96618. Pulled the pistons out of my wheel cylinder and pried off the old seals. Then I noticed that the hole in the center of the old seal is much larger than the hole in the new one and it would be an enormous stretch to fit one of the new ones onto the piston. Also, the new seal is thicker and doesn't fit the groove in the piston. I've got a set of old cylinders from a parts car and the pistons and seals in them are the same as what's in my car. In other words, I have the correct cylinders and pistons on my car. I didn't try real hard to stretch that new seal onto my piston, but I don't think it's going to work. Did they change the piston design somewhere along the line and I missed the memo? Did I somehow get the wrong rebuild kit, and if so, what's the correct one? Here's a pic showing the old and new Hard to tell in this pic, but the new seal is thicker than the old one: Here's one of the packages and you can see the other part numbers it's compatible with: What the heck???

I would be careful with the brake cleaner and the AAR... There's some wiring in there and I don't know how the insulation will like being soaked with the solvents. Use a little and quickly shake out the excess, but I wouldn't dunk it in a can of carb cleaner. I remember that cool pic you were talking about from Fastwoman... I did some digging and found it in the "Post pics of your engine bay" thread. http://www.classiczcars.com/forums/thread45781.html Even though the routing is a little different, the function is still textbook "78 style". AAR pickup is off the flex tube upstream of the dirty PCV overflow. I like it too!

Sorry I couldn't be of more help. So if you do end up pulling the dash... What year are you working with? I just pulled dashes out of both a 74 and a 77, and the 77 was easier. The 74 required disconnection of a bunch of electrical connectors at the steering column, and by the time 77 rolled along Datsun had gotten a little smarter and rerouted all those connections to the firewall. The only electrical connections you have to mess with in 77 are three large connectors all located at the junction box above the passengers right knee. Leave all the HVAC stuff in place. You don't have to mess with any of it to pull the dash. In fact, you can even leave the faceplate with the map light and fuel warning light in place. Leave the glove box in place as well. Don't forget to disconnect and reconnect the speedo cable. What else...? If your clock doesn't work, it's a lot easier to remove with the dash out of the car. If you find an evaporator core in the top of your HVAC system, then you used to have A/C.

Gotcha. Well my 77 still has all the original 77 routing, and I'm nipple-less, so I guess my car never got the treatment. I wonder if anyone ever came up with a way to plumb to the dirty side of the air cleaner without confusing the L-jet.

Here's a pic of the water control valves. The spring loaded over-engineered device on the right is controlled by the temp slider, and the flying saucer shaped diaphragm actuator on the left shuts off all the water when you turn the A/C on regardless of where the temp slider is positioned. I'm no expert on the HVAC system, but I'm still thinking that maybe you shouldn't have any vacuum stuff in there at all unless the car has A/C. Maybe your car had A/C at one time, but a previous owner removed some (but not all) of it? You've got the vacuum switching valves in the engine compartment Is the hose going to the diaphragm the one having troubles with?

Thanks for that info. So was there actually a recall for this? Was everything supposed to be updated to 78 specs?

280~Master, you are running the stock configuration for 76, which is the same as 77. Interesting to note that you have the unused nipple on the flex tube at the front of the throttle body. Seems your flex tube has been replaced at some point with a newer one. I wonder if maybe Nissan stopped making the original tube without the nipple, and just started supplying only the one with the nipple. They would only have to stock one part that way. Anyway, you've got the correct setup for 76, but you could re-route for 78 if you chose to. BTW - Nice tape on the AFM... Looks just like mine, except I'm rockin' green instead of red!

Yup. You got it. You are now using the "78 scheme". Your throttle body will still be a mess, but your AAR will thank you.

I will wear my new mini-mag-glass with care. Not sure what you consider "early" Z, but I've found a mistake on the factory diagrams for 74 (and maybe 73... don't remember) temp switch wiring. If you're doing anything with those docs, let me know and I'll provide details.

No apologies necessary! None!! This document is fantastic, and even counting the tail chasing this time, this document adds so much value that I'm way ahead of the game! I'm not aware of any other issues at this time. Thank you!! I applaud all the efforts, and I'm just glad I could help make an already fantastic document a tiny bit better.

I think I have retraced my steps on where I first found copies of the color wiring diagrams... I think I first heard about both 77 and 78 here: http://www.classiczcars.com/forums/thread44992.html But the 77 version appears to have originated earlier here: http://www.classiczcars.com/forums/thread13131.html So from the above two threads, it appears that wal280z did the 77 version back in 2004 and awolfe did the 78 version in early 2012.

I picked up this diagram some time ago but unfortunately I don't remember the thread that originally turned me on to it. I'm pretty sure that it was on this forum though. I believe (especially because of the ClassicZ mention in the legend area) that the owner of the document hung out here. I was hoping that he would pop up... As for the problem that I chased? It's in the fuse block: For comparison, here's a snip from the 77 FSM: Important to not also that the 78 color diagram is correct. It's just the 77 that has the problem.

Very common issue with our L-Jet systems. Search around here and other Z sites and you'll find lots of people with the same problem. Lots of band aid solutions too as well. As for whether it's rich or lean? The common belief is that it's running lean.

The vacuum control lines only exist on the cars with A/C. The non-A/C cars are completely cable actuated mechanical only. That's why I asked if the car had A/C or not. I'm not sure what lines he's talking about here. I'm not sure if he's talking about the vacuum control line to the ON-OFF A/C derived water ****, or is he mistaking the hard copper line to the temp control valve for a vacuum line? In any event, I'll jump to the end of the chase here and say that I've recently messed with my system, and it all depends on how small your hands are and how long you can work while laying on your back with your head up under the dash. I don't think there's any vacuum line that you cannot get to if your hands are small enough and you are flexible enough to deal with the contortions. However, I've decided that if I ever have to do major work to the heater system again, it would be easier to just pull the dash. It's just not that hard to pull it, and working on anything heater related after that is just so easy that it's not worth it (for me at least) to try to do anything significant with the dash in place. Here's my bottom line... If you've got one tube that is leaking and you want to address just that one, then maybe preform the contortions. But my guess is that if there's one that needs to be replaced, then there are probably several others that should be as well.

I picked up a color wiring diagram for 77 on the forum here somewhere... Is the owner of said document still around? I've found some mistakes. I just spent two hours chasing my tail and I want to prevent anyone else from doing the same!

Now that's something interesting that I never played with... Who knew? (Probaby everyone but me)

Bruce, Let me see if I can help. What's going on here is that he fills the dampers up to (and not above) the fill-to line scribed into the stalk, drives around for just a couple hundred miles and then checks the levels again only to find that the level has dropped significantly below the fill-to line. He has stated that he is not overfilling the tubes to capacity and then displacing fluid up and over the top when he puts the stalks in. What makes the situation interesting enough to warrant two pages of forum is that he is not overfilling the dampers and then wondering where the oil went... He's filling them to the correct level and then wondering where the oil went.

Are you talking about the vacuum control lines (which only exist on the cars with air conditioning), or are you talking about the hard copper line that comes out of the top of the water control valve? (Or something else completely?)

Haha! Lucky shot! I had my eyes closed to boot! If you do what you described above, then you will end up with exactly how Datsun did it in 77. The only difference would be the existence of the (unused) nipple on the accordion boot. Would that fix your oily throttle body? I don't think so. Other than reducing the blow-by as much as possible (by engine overhaul work), I don't think there's anything you can do to get rid of it completely. You need to plumb that PCV vent tube to the atmospheric side of the throttle plate somewhere... There's just no way around it. Many newer vehicles run that line to the dirty side of the air cleaner, but because of the way the air metering is done with our L-Jet system, that's not an option for us. However... Even though it wouldn't fix your oily throttle body, it would be simpler. The plumbing scheme you've currently got I consider to be the worst of both worlds. You've got the extra plumbing for the 78, but because of the way you have things routed, you aren't getting the benefit of a clean air stream for your AAR. You've got the dirty valve cover tube still going upstream of the AAR and the throttle body. I'm thinking that you can make it simpler by doing what you proposed and going back to the 77 scheme. You won't see a cleaner throttle body, but at least it's simpler. My thoughts on the 78 routing is they didn't do anything about oil in the throttle body, but at least they managed to clean up the AAR. Does that make sense? Do you understand the difference with routing in the 78 pic I posted? in 78, Datsun has the valve cover piped to the throttle body and the AAR piped to the accordion nipple. You have the valve cover piped to the accordion nipple and the AAR piped to the throttle body.

Haha! I'm really sorry... I still can't figure out what you're trying to accomplish, so I'm gonna shoot in the dark and hope I hit something valuable. They changed some of the PCV and AAR air piping between 77 and 78. In 77, it looked like this (sorry for the crappy pic). They pulled the air for both the upper PCV tube to the valve cover and the AAR off the same point on the throttle body. That point is just on the upstream (low vacuum) side of the throttle plate inside the throttle body: In 78, they added a rubber nipple to the flex boot on the intake side of the throttle body and split up the air intakes for the PCV from the AAR. The PCV still got it's air from the same place as 77 (upstream of the throttle plate in the throttle body), but they moved the air intake for the AAR farther upstream to the new rubber nipple on the flex boot. The boot is missing from this pic, but at the very bottom of the pic you can see where the metal tube leading to the AAR would connect to it: I've not got any real info on the reason they made that change, but I would speculate... On my 77, I get a lot of crud that comes out of the valve cover and through that upper PCV tube. I don't know if I've got too much blow by for the PCV to handle or what, but all I know is that it's dirty. So in my 77, I've got this dirty air stream coming off my valve cover, only to be sucked back through the AAR into my manifold. My AAR doesn't like the dirty air and gets really cruddy inside as a result. So my speculation is that Datsun figured this out, and in 78 they changed the piping to split those two sources and moved the AAR intake farther upstream into cleaner air so it doesn't pull through all that crud coming off the valve cover. None of this stuff will have anything to do with how long it takes your engine to warm up. If your AAR is dirty inside from breathing sticky oily residue from the valve cover, then it may take longer than it's supposed to for your AAR to close. Won't take the engine longer to warm up, but it may take longer than normal for the idle to drop. So, like I said, shooting in the dark, but hoping I hit something!

What's the question? What do you want an opinion about?

Yes! Exactly! I had the door panel off my Honda not long ago and I saw that same stuff. Sticky enough to hold at first and still somewhat tacky years after, not a sticky spreadable gooey mess like that butyl I spent so long cleaning off everything. I was thinking of asking if anyone knew what that stuff was, but wasn't sure I wanted to pollute the Z forum with a Honda question.

I haven't looked hard for other options, but the only version I've ever seen available for download is at http://www.xenonz32.com/reference.html.

Thanks again Jim. Your stated advantage for the cast iron manifold is exactly one of the reasons I'm considering going back. Less heat in the engine compartment is another one. I suspect most people would think I'm nuts to go back, but I seriously doubt I've got any performance gains with the header. Only advantage I think I have is the "coolness factor". As in "Cool! You've got a header in that thing!". I'm so past that... I've got the stock manifold for my car. PO put on the header, but included the old parts in a box. I was just thinking that if I was going to be putting on a cast manifold, it wouldn't be any more difficult to put one on that already had a bung built in (like 81 and up NA). And I could put a bung in the exhaust pipe, but I always thought the closer to the engine and the hotter the better?

Right. That's because the valve won't do anything until it's submerged. The point is, however, that having a good air seal above the valve is a red herring. Here's a way that you can feel the effects of valve misalignment: Fill the damper tube to it's proper level and then insert the valve stalk and push straight down on the screw knob until the threads contact the top of the body dome. Once the valve is submerged, you should feel the resistance caused by the properly closed valve (just like you described above). Then pull the damper completely out and repeat the same procedure, only this time jiggle the damper stalk side-to-side as you as you push it down. You should find that the amount of force required to push the damper "home" is less. The reason is that when you shift the damper stalk from one side to the other you misalign the valve's sealing washers and it cannot properly seal with that much misalignment. I'm a big fan of pictures too, and I'm sorry that I don't have any to help describe that process. Hope the text makes sense.