FastWoman

I think my 12/77 '78 is the same as TomoHawk's. The floor is all in one plane, but with wastage of maybe 3" all over. All the trim work is there, extending down to the metal floor. The carpet, which the PO replaced, extends throughout the entire hatch area and drops over the edge of the masonite false floor, which comes just short of the trim all the way around the back. The spare tire recess is maybe 3" into the metal floor. The spare tire compartment lid is hinged about midway in the hatch area, with quarter-turn latches on either side. I haven't tried taking it all apart, but the metal supports beneath the masonite deck all seem to be bolted in place. I don't know whether the threaded holes open to the underside of the car. I can't really see very far forward (haven't tried very hard) to know what lies under the forward part of the deck. In my '75, I had two nice hinged storage compartments behind the seat that were difficult to access because of the carpet. Anyway, it sounds like there were all different designs in this short production period. MEZZZ, with the masonite floor stripped out, is your floor flat enough to simply lay down a carpet -- perhaps with a smaller masonite panel to cover the spare tire dish? I notice the wiring harness runs conveniently towards the righthand side of the hatch area and shouldn't be too badly in the way. Maybe with a thick mat carefully inserted, it would all flatten out. So is there a skinny spare tire that would fit better in the shallow spare tire recess? (The "spareless" approach is tempting.)

Hmmm.... Mine was made in 12/77 (1978 model), so maybe it was a partial year thing. I need room for groceries, of course! It's hard to stand up a bag at the very rear of the hatch area. A few extra inches of height would be great.

Hi all, When I recently bought my '78, I kept mentally comparing it to my old '75 that I sold in the early 90's. It seemed to have less space in the hatch, even when taking out the subwoofer in the back. To my embarrassment, I now know why: It has a raised false floor. Weird. Why would they do that? The material is rather heavy, the floor isn't as sturdy, and most of all, there's not as much room in the hatch. So has anyone converted one of these platform floors to a regular floor? Are there any surprises involved? I suppose one issue is the spare tire. The one I have is the original style, stored deflated. It's quite wide and stands up to the height of the spare tire lid (or false floor). Is there a skinny substitute spare tire that can fit this space with a fiberboard cover such as I remember on my 1975? (I recall having a full size spare in that car, though. Am I imagining that?) So what do people do, when they don't like the raised hatch floor? Thanks! Sarah

Thanks, guys! I guess if good differentials are that plentiful, I'll just drive with this one until it presents a problem. This might be like the ripped drive shaft boot on my little Saturn. Every mechanic who's looked under my car has insisted I should spend the $300 to replace the boot, so that the drive shaft doesn't wear out. The price to replace the boot AND shaft is perhaps $30 more than that. I decided about 50,000 miles ago just to drive it until the shaft went out and then to replace both the shaft and boot together. The thing still hasn't failed. ;-) I might drop in on a TZCCVA meeting sometime. Unfortunately VA Beach is a bit of a drive for me, as I'm on the other side of the bridge tunnel. The last time I drove to VA Beach, I felt like I was driving in the Daytona 500 -- some crazy moves by some of those drivers! Do y'all ever do anything on my side, where it's all calm and peaceful? I have yet to talk to Todd at Tidewater Z. I will eventually. I'm just working my way through as much as I can on my own. It's part of the bonding process, and it's a lot easier on my wallet. I figure I'll reach a point where I need a more seasoned opinion or where I'm stumped about something, and then I'll drive the few miles to see him. Thanks again! Peace, Sarah

Hi all, So... I got my fuel pump all connected back up, new lines, etc., and thought I would change the differential oil while the car was jacked up. The oil was sort of brown and slightly smelly -- not a burnt smell, but another smell that is somewhat hard to describe. The magnetic drain plug was slightly "hairy" with filings stuck to it. There was the tiniest bit of debris in the bottom of the pan I collected the oil in. Some of it glittered (i.e. filings). The longest filing I found was about 3/16" long and about 1/16" wide, but most of what I saw was about 1/32" in size. When I was finished refilling the oil and cleaning up, my hands were a bit glittery too. My differential has been softly whining at highway speeds on deceleration and coasting (i.e. with engine speed matched to coasting speed, no power applied either way). It often clunks when I change gears. Finally, there is a bit of leakage of oil from the side seals. The sides and bottom of the differential are quite well covered with oil deposits. Having recently bought the car, I don't know how long all this has taken to develop. The differential oil has been changed before, judging from the rounding of some of the facets on the fill plug. I've notice no change in behavior, noises, etc. since I've owned the car (about 2 months now). So is accumulation of filings sometimes normal, or does it sound like I need a rebuild? If the latter, whom do I find to do the work, and what should I expect it to cost? My local resources are a Nissan dealership and a local Z specialist, as well as a multitude of good machine shops in Norfolk. I'd appreciate any disinterested third party advice before taking my differential to someone who wants my money. Thanks! Peace, Sarah

So all that's left is the ampacity of the lines. That's where it gets kinda weird. Previous threads suggest the following values for the different links: black (1.25mm^2, 16 ga) 80A green (0.5mm^2, 20ga) 40A brown (sometimes called "red", 0.3 mm^2, 25 ga) not mentioned These links would ordinarily protect (by manufacturing convention) lines that are 4 gauge numbers larger in size... black protects 12ga green protects 16ga brown protects 21ga The AWG ratings for open air applications for these wire sizes are 12ga, 41A 16ga, 22A 21ga, 9A Thus the ratings I've seen quoted here are about double the open-air ampacities of the lines they would supposedly be protecting. (I don't know the actual guage numbers of the wires used, though, without actually cutting them and measuring. Does anyone know what they are?) The highest demand on any circuit would probably be from the alternator wire. I'm guessing that's protected with the black fusible link at supposedly 80A. I'm pretty sure the OEM alternator puts out 60A. Thus 80A seems a bit high from that standpoint too, but it also seems cranking 60A through a 12ga line is also a bit ambitious. So I'm left wondering what the real ampacities of these circuits really are. Can anyone shed some light on this issue?

FOUND IT! I did find diagrams in the FSM where the wiring harnesses were strung. (I wish there were an index in the thing, because I would have found it earlier.) There I saw that there were large junction block connectors between harnesses just inside the firewall. My G/B wire was in one of those connectors. I pried apart the connector with some difficulty, only to find a crusty, somewhat melty connection inside. There was good continuity from the respective connectors to the ends of the wires. I cleaned up that connector and the adjacent one with WD-40, working the connections pretty liberally. Then I connected it all back up and started my engine. Yipee! The weird resistance readings (which I corrected in the above post, as I couldn't see the "k" on my auto-ranging multimeter from where it was perched atop the exhaust pipe beneath my car -- thought it was 65 ohms, not 65 kOhms) were due to a half-cell reaction in the corroded connector. There was a tiiiiiny voltage between the two ends of the wire and between the corroded connector and ground. That was enough to trick out my multimeter into reading the wrong resistances -- 65k in one direction and 366k in the other. Had I reversed my probes, I would have found the opposite. Lesson to be learned: When troubleshooting a large wiring harness in a possibly corroded piece of equipment, don't use the ultra-sensitive, ultra-low current multimeter. Instead, use one of those cheap mechanical ones that puts out a higher test voltage (and won't be tricked out as much). And then when you get a measurement, try reversing the probes to see if you get the same measurement. If you don't, there's a tiny voltage inserted somewhere, and there may even be some rectification going on -- good evidence of corrosion between dissimilar metals. Anyway, I'm running again. Yipee! BTW, I do appreciate anyone who might have taken time to do some head scratching on this problem, even though they didn't think of anything to post. Peace, Sarah

Could use some help here -- an "uh huh" that I'm not on the wrong track, before I start tearing into body parts and wiring harnesses! Better still, perhaps someone knows a trouble area or two where I should start looking. After the rain let up, I was able to continue testing. I was finally able to break all that epoxy (?) off of the + terminal on the fuel pump and lift that wire -- a green wire with a light blue trace. I was similarly able to pull the wire from the plug to the fuel pump relay. Same color code. Both connections were clean and bright. No question there's contact between the connector and the wire. I quickly jumpered between the battery and the + terminal on the fuel pump. It pumped. I then did a conductivity test on the wire between the engine compartment and the fuel pump. I read about 366 kOhm. From the fuel pump side of the wire to ground was 65 kOhms. Not surprisingly, the resistance between the relay side and ground is about 366 kOhm. One might think the wire has been severed somewhere, with the pump side of the wire lightly touching ground (65 kOhms) and the other side not. This hypothesis seems inconsistent with the fact that the pump worked for a few moments a few days ago before it failed again. The rubber grommet is in good condition where the wire enters the body beside the fuel pump, so the problem isn't there. Any recommendations where to look? Locations where wiring harnesses might get bound up, rubbed, or cut? Any information would be greatly appreciated! Thanks, Sarah

This is a nice little 4-gang distribution block: http://www.darvex.net/Stinger-4-Gang-Gold-MAXI-0/M/B001IQIW78.htm?traffic_src=froogle&utm_medium=organic&utm_source=froogle

I'm still researching amperages. These links might be useful to someone: http://whiteproducts.com/fusible-faqs.shtml http://whiteproducts.com/fusible-specs.shtml

Thanks, TomoHawk! The maxifuses do look like a good possibility -- probably a lot cheaper than the breakers. I have SIX fusible links in my '78 -- four under cover and two in a double-connector clipped to the side of the relay housing cover. Yeah, part of the motivation of the redesign is to get rid of the covers. I'm still wondering, though, whether I'll be hurting the value of the car by straying from the original design. My car is perhaps 99% stock. Even though it looks great, it's not a "show" car, and I intend to keep using it as a daily driver. Considering that, I think a small mod here or there isn't really going to hurt the value. Is my thinking correct here?

Hi all, My fusible links are in horrible shape -- rotted, corroded, yet still conducting for the time being. Yeah, I know, replace them. One of my fusible link assemblies has a broken base and is just dangling on the ends of the wires. Both covers are rotted. The only replacement items I'm finding are the covers. I'm sure I can find the wires too. perhaps a base at a junk yard. Even so, I wonder whether I shouldn't just replace the whole mess with something more practical. I'm thinking of installing breakers like this: http://www.wiringproducts.com/contents/en-us/d29.html ... or perhaps a very heavy duty fuse holder. How do I find the amperage ratings on the fusible link wires? I have listed in the FSM that the black links are 1.25mm^2 (approx 16 ga), the green ones 0.5mm^2 (approx. 20 ga), and the brown ones 0.3mm^2 (approx. 25 ga). How do I find out at what ampacities these fusible links melt? Also, has anyone replaced the fusible links with fuses or breakers? How well does this work. Any thoughts about straying from OEM, even if it means an electrical upgrade? Thanks for any input on this one! Peace, Sarah

Hi all, I was out on errands a couple of days ago and had my '78 fail to start at the post office. Had it towed home a few blocks. Thank god for AAA. After a bit of diagnostics, I found I had no fuel pressure. I pulled out the FSM and started fault tracing. I found that the ignition relay, the fuel pump control relay, and the fuel pump relay were all working fine. I had +12 to the fuel pump relay with the ignition switch in the start position. Also when I jumpered across the plug to the fuel pump relay, the pump kicked in. Cool. So I plugged the fuel pump relay back in, and everything worked fine. I figured it was just a dirty contact somewhere. (Lots of dirt in that box>) So I spent the next half hour cleaning contacts with WD-40, working them well, etc. Then when I put everything back together, SAME PROBLEM AS BEFORE! Thus is was my most favorite type of problem -- an intermittent one. This morning I went back to fault tracing. I jumpered across the fuel pump relay connection again, and no fuel pressure. I then did a resistance check from the fuel pump relay connection, presumably through a fuel pump, and then to ground. There was no conductivity. Something was open. So I figured it might be an intermittently bad fuel pump. I then jacked up the rear end of my car, chipped off some of the insulation painted over the fuel pump connections, and measured voltage across the terminals. I couldn't measure any voltage with the key in the start position, and there was obviously no fuel pressure either. I also did a conductivity test across the terminals of the fuel pump. (The reading was 1.1 ohms. Normal, or somewhat low?) Then wondering whether the unit was grounded, I did a measurement from the two terminals to the bumper. That was about 4-5 ohms, depending on the terminal, and whether the motor was in series with the measurement. Seems a bit high, but then again, I was measuring at the bumper, and someone else was holding the probe to the bumper for me. So I'm guessing my relays are good, and my pump is good. The fault lies somewhere in the wiring between the relay and the pump. But where? The FSM doesn't seem to indicate a connection between those two points. Is there one? Any common failure points I should be looking for? Frustrated in Virginia, Sarah

condenser coil

I had the same misapprehensions about the S/N when I bought mine. It's indeed an old format. It should start HLS30 (or GHLS30 if it's a 2+2). After that might be an A for automatic or an F for 5-speed, U for US and Canada, V for California, N for Canida, and C for air conditioned.

FAIW, you can run the output from the stock radio to a power amp hidden below a seat, if you're not content with 3.5 W but want the factory look. I also really like the look of Mike's rear panel. Put all of this together, and you'll have OK sound -- but sound that you can actually hear. Note that much of that 10% THD will disappear when the radio unit isn't driving as much load.

DougN, you need to wire the power lead from your electric antenna to the battery circuit, rather than the accessory circuit. Then it will go all the way down when you shut off your engine and remove the key,.

It sounds like you might have the vacuum lines reversed. One nipple is slightly lower than the other on the magnet valve. The lower one should go to the fast idle actuator. If the upper one is connected to the actuator, that line will not vent when the magnet valve is shut off. Furthermore, you'll have a vacuum leak when the HVAC system is running without the A/C compressor clutch engaged.

Cool ideas. I've found that my engine hardly notices when it's pulling the compressor, so I don't think the idle increment is all that necessary anyway. Your use of the power booster as the vaccum reservoir is very appealing. I can understand why Nissan wouldn't do this, though, as it could expose them to safety liability claims, should a leak be introduced from the HVAC system. Having just been into the control assembly, it seems to me that you could simply wire a microswitch in that would engage the compressor relay when the lever is in the bi-level position. I'm not sure EXACTLY where you would put the switch, but there's plenty of room in/on that thing. I'd probably put a small bolt with a rounded head through the lever to create a "bump" that would trip the microswitch. That could be wired in parallel with the other microswitch. I think it would also be possible to attach an extra bump or nub on the lever to engage the microswitch that is already there when in the bi-level mode. That would probably be more elegant.

I'm not talking about the check valve. I mean the "magnet valve" (i.e. one of the two doodads connected to two tubes and two wires and mounted to a bracket on the fender). Anyway, I remembered its hookup wrongly. The way it was originally configured, it vented to the vacuum selector valve side, not to the vacuum bottle side (see pp AC12-13). Thus the vacuum bottle would stay under vacuum either with the original configuration or with the way my system has been reconfigured. The vent to the HVAC side seems to be redundant with the vent passages in the vacuum selector valve. I'm wondering why they even have that "magnet valve" in the design.

Hi all, This weekend I finally got around to tracking down that last vacuum leak -- in the pneumatics of the HVAC control apparatus. (I had previously identified a leak through the vacuum line leading through the firewall from the vacuum solenoids or "magnet valves" -- righthand/passenger side of hood compartment.) The larger source of the leak was immediately apparent. In their infinite wisdom, Nissan put a splice in the vacuum line in the righthand/passenger dash area. It's shown in the factory service manual diagrams. It seems like that's just more to go wrong, but I'm sure there was an assembly line rationale behind the splice. In my own case, I had three splices, apparently from repairs by the previous owner. The tubing was starting to rot and had split over one of the splice connectors, then falling off. So I did a quick fix of the splice and found that I still had a vacuum leak. Not surprising. Anyway, I had to tear into the dash to track down the remaining leak and to replace old tubing with new. (Joy!) The center console on my '78 didn't come out as nicely as I had remembered on my '75, but I got it out. No leaks in any of the vacuum actuators in the system. The leak was definitely in the vacuum selector valve. It looked as though I could simply remove it from the bottom of the control assembly, but I wasn't sure. I figured I'd be better off taking the conservative approach and removing the entire control assembly before worrying about the vacuum selector valve. This gave me the opportunity to clean and lube it, but in hindsight I would have left it in place, only removing the vacuum selector valve. There are too many things to take loose and reconnect, and the assembly doesn't really come out without a bit of a fight. Once I had the vacuum selector valve out, I was able to confirm that, yup, it leaked. It seemed like a rather simple construction -- and was. It consists of two metal plates faced against each other, sealed with vacuum grease. The design of the valve is such that it vents air to the actuators to allow them to relax. The problem is that dirt is sucked into the valve and combines with the grease over time, eventually resulting in accumulated gunk that doesn't seal the two plates together very well. Anyway, the valve disassembles very easily. Just remove the little c-clip on the shaft, and the valve disassembles into 5 parts -- the two plates, the shaft, the clip, and a spring (on the outside of the assembly, pressing the plates together). There was a bit of scoring on mine from the dirt, but it was very minor. I just cleaned the two plates, lubricated lightly with silicone vacuum grease, and reassembled. Note that there is a recess in the middle, right around the shaft. I packed that recess with extra grease to feed out over time. In the original assembly process, Nissan had apparently not packed this area. After reassembling, to my delight, the assembly was vacuum-tight. I reassembled the whole mess, properly adjusting the cables, and found that the HVAC system worked perfectly and my engine had no remaining vacuum leaks. Yea! Here's what I would have done differently -- things that the factory service manual doesn't tell you: Rather than taking out the entire HVAC control assembly, I would have removed the vacuum selector valve from the bottom of the assembly. The cleaning/lubing of the remainder of the control assembly simply isn't important enough to go through the headaches of R&R. To do this, I recommend the following procedure, and I'd advise penciling it in on the appropriate page of the factory service manual (page AC-31 of my 1978 manual): (1) Turn the mode lever to "defrost" (far right position). (2) Remove the two screws retaining the vacuum selector valve, and remove through the bottom of the assembly (very easy). Be careful not to turn the two plates (also very easy). Note that the selector valve could install either the way you took it out or 180 deg turned. I'm pretty sure from the construction of the valve that it would make no difference how it is turned during reassembly. Note also that the drawing of the vacuum selector valve in the factory service manual is not accurate, at least on my car. The nipples are located in different positions. Perhaps there is more than one configuration of valve. (3) Note when you remove the valve that the top and bottom plates have alignment pointers on their outer radius. In the "defrost" position, these pointers should be aligned. At least that's how it is on my valve. Again, there may be different configurations. If the arrows don't align, then make your own alignment marks. (4) Disassemble, clean, re-lube, and reassemble valve. Use silicone vacuum grease or (silicone brake grease?). (5) Realign the plates using the alignment arrows. (6) Without rotating the plates, reinstall into the assembly, gently meshing the gears together. (7) Check the final alignment with the air selector lever now in the A/C position (far left). In this position, the S nipple should be completely vacuum tight, and the other three nipples should vent to the outside. I believe this is the only position where this would be true. One final note: One of my "magnet valves" is bad in the engine compartment. It is the primary one that evacuates the reservoir when the HVAC system is turned on. When the system is turned off, it is supposed to vent air back into the HVAC pneumatic system (note: edited as per below), thereby relieving the vacuum on the entire system. (There is a little filter on the bottom of the valve.) In my car, someone had bypassed that valve. I was worried that with a healthy vacuum and no leaks that the vacuum actuators might remain actuated when the system was turned off. However, the design of the vacuum selector valve does vent air back to the actuators when the system is off. I suppose the vacuum reservoir does hold a vacuum when the system is in the A/C position and the HVAC system is shut off. I presume that's not a problem. Anyway, I hope this posting saves someone a few headaches. Peace, Sarah

I assume this link is in another thread, because I don't see a post from "Mike B" in this one. Could I trouble you for a link to the thread or to the parts supplier? Also, what club CD are you referring to? Is it a digitized parts microfiche? I've downloaded a parts microfiche, but it's so illegible that it's mostly useless. Thanks! Sarah

myfairlady, don't replace the voltage regulator -- or the alternator. They're both fine if your system puts out up to approx 14.5V (and not more). If your battery is new and healthy, then the voltage should not drop below 12 or 12.5 V, give or take, depending on your charge state. Does your starter seem to turn the engine pretty well? if so, it's not either of the battery cables or the battery connection. Instead, I'd start checking the fusible links for corrosion. I think that's the most likely trouble spot. I think you'll get some clues where the problem is if you do a few spot voltage checks. With the lights in their dim state and the volt meter in the middle of the gauge, take measurements at the battery, at the alternator, at the fuse block, and possibly at the headlights. I'm betting alternator voltage and fuse block voltage are about the same (low), and your battery voltage is in the neighborhood of 12.5V. Then do some fault tracing to find where you experience your big voltage drop. Again, I bet you'll find a drop across the fusible links or their connections. I bet something will even feel pretty warm somewhere. Good luck! Sarah

From all you've described here and elsewhere, it sounds like dirty/sticky valves. You might have swollen some varnish with the sea foam, causing the valves to stick worse. If you keep cleaning, the problems should eventually resolve.

.10/.12 inch is hot. Cold values are .08/.10 inch. Could be dirty/sticky valves.