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Have water in oil, cyls 2-6 fine, nr 1 plug wet, water in oil. Suspect it is head gasket but not sure. Do not have place to do head gasket nor tools, etc, so will have to pay to have done by local NAPA or such (use their head gasket set?) Have had work on truck done there, great place, mechanic i former Datsun shop. Est is 525 plus tax, is that reasonable? IF worse case is head cracked, what is real cost for replacement head. Need to go cheap as 73 on SS, so not a lot of spare cash. Thoughts? Have had 78Z for 25 years, used to do most work self, but back no longer accepts such things. Ole machine and I still run pretty good despite age.

For now have the thing fixed. I simply started at the point where power goes on to systems, there are TWO wires that go to the inline fuseable links. They seem to have ONE common hook up at starter/battery post. ONE of the two was shorting out to some wire in that harness. I simply built new wire with TWO leads, ran it from battery to the fuseable links, and ALL is OK. I am now taking that harness apart, and going to try to ID those other wires in the harness. My GUESS, the hot off battery wire (only one of them as other systems behaved fairly normal, but one of them shorted out into a wire in harness that activated the pump, brake light, etc,. When new wiring installed all worked fine, but hesitant to drive it until I find what was going on inside harness. NOTE if you do this fix my way, make sure the OLD wires cut off, the one off battery and the two to links. For now cut them so they cannot touch anything, then covered in ele tape. Want to find what was going on in harness and will post that. Delay in work as other priority(s) like PC pwr supply, graphics boards, etc.. What happens is if you check for one place all the failure can come from you end up with ign relay on 78, it is only common spot or so I thought. Took hours just to put everything back to normal place.Now that pesky harness, it is one that runs wire from battery and two out to the links. Has other wires, will find their function next. This one was a evil little failure, very hard to find but read where others had same, so perhaps other years have power up to links issues?

Just on outside chance, tried hooking batter back up. Guess what, same error went on WITHOUT relay OR ign switch hooked up. So went back to wiring diagram as for now appears that Ign Relay is NOT the issue. Went from batter out, found on mine there is wire from battery pos to the fuse links, then another from starter to other fuse link, when tape removed it seems like someone added it. Further mess is a white wire at same point on starter as post, bat, other wire to fuse links. When that one touches pos/black wire at terminal, same ole thing happens. Note the way all was hooked up was done by previous owner and looks like black wire to fuses is part of harness. Noted on FMS section on electrics that charge lite gets message from ALT and power from fuse box via a "L" wire, did NOT (yet) see it in the FMS wire diag, but may have missed it. So back to the ole meter and various checks. but with relay out, key harness off, why EFI pump fires up, charge lite on, and brake lite on, getting a bit freaky, more so as at one time the issue solved self with turning key off on a few times. Have yet to find a common issue that runs this stuff when Ign Rely out, key harness out, and such. By the way, do you know the physical location of the call out for starter sol, know which one is ign, but what is the other two, one to right side and other engine side, which is which via FMS? Kind of losing faith in my own checks now as maybe doing something wrong, repeatedly?

As I mentioned, the same thing happens when the key switch Harness is disconnected, early on in the failures when they were random, turn key off/on and it went away. Unplugged key switch from harness and still happened, skewmatics indicate only central item that impacts all this stuff is the Ign Relay on the 1978 280Z, now understand why they only used this PN on one yera.

THANKS MUCH, somehow missed them, nice site as wife has 93 240SX convert that will be back on road as soon as auto trans either repaired or replaced, her "Baby" as she loves it, gets great MPG and rolls out quite well. Now to the Ign Relay, ordered one and it seems both the 25230-89958 and B5230-W0500 same part as exactly same price. Did not do parts check on each yet. Went over the ign swtch and Ign relay and even the no charge, lite. Seems that the wiring D is screwed up, and now really wonder if anything else is wrong. Will try and ID prongs to do some tests with my unit, but ordered another one anyway. I just cannot see anything else that could be causing the issue with all the other items going down. It seems in the 78 the ign relay just central point for most items power ups. Any ideas as if issue could be from other then Ign Relay, as so far that is only spot I can find that ties them all in together., Sure wish I knew what gap was supposed to be on those things as really seem huge right now, more so compared to others in EFI/Pump etc. This sure is a mystery part. Again THANKS so much for source, somehow missed it, very much appreciated. Wife now after me for new auto trans for her beloved 240Z, note she just loves the newer GT R's, but we have never seen or driven one and can only guess at ins rates there

When I hook up battery, KEY OFF, also with Key harness unplugged at key, following things happen, EFI relays under hood active, fuel pump starts, no charge lite on and volts show 4-6 with engine off, fully charged battery. seat belt like on, in general acts same as if key turned on but not at start. This thing started as intermittent, fixed by turning key on/off a few times, then went full time and would drain battery overnight if left hooked up. Sounds were at EFI relays under box, right side under hood. Thought maybe they were issue, but checked all out and all OK, replaced ALT as sometime this can cause issue, no change. ONLY way to shut off no charge lite is to remove two prong from ALT. NOTE when power turned on the Ign Relay made no noise, none, It seems only common point to all the problems as seem stuck in some sort of "Ign On" position but gaps are open (amazingly to what appears nearly 1/16th inch or so, not burned. They, so far are ONLY points that are fully adjustable via set screw if I knew what they should be set at. I may try to power up the unit and test from there, I would like to test the harness plugin but it is in nearly impossible spot, but if twist and turn enough might be possible. Note it seems to work with power on from ign key makes circuit and opens others. Not sure if the is points open or closed, would suspect closed, but very large gap is kind of strange. A bit baffled by this one, more so as simply cannot find any for sale for 1978 and this PN seems neither substituted nor in stock anyplace. A bit odd as ONLY used on 78, so doubt others would work and could further screw up electronics? Going back, suspect this unit is bad, somewhere as only one that ties in directly with old key on off fix and impacts other items now going on. It seems the LR out of key swth looks like a ground to ign swtch, and LR from fuse box runs to fuseible link and condenser on alt. That LR from Key is odd, you are right about error there or is it? Will look at closer at Ign Relay uses on FMS as they show lots, but wonder about testing the thing now? Sure wish one was for sale.

My dreawing from FMS for 1978 280Z shows 6 wires from IGN RELAY, you may have different year or are looking at the Tranistor IGN UNIT, a easy error to make. NIssan parts guy did same on first pass, then went to find IGN RELAY. Note in FMS for my Z IGN RELAY is in section on Bracket Reg, Body Electric etc, and covers wiring, location etc. NOTE have taken unit apart and noted (I did same for relays related to EFI under hood, this one above fuze box on "relay bracket") this relay has actually adjustment screws on the contract points at top of windings pole, none of others so equipped. No burn marks or pitting on points, but REALLY odd gap as appears about 1/16th inch on both. Not much left of points as probably down to 1/64th or less, but no indication of burning, shorts etc. So far cannot find what their gap is supposed to be, what amps etc. This is ONLY year that uses this PN and 79 on different. Will search again for testing but so far no luck.

Cannot find a check method in my FMS, maybe missed it. Issue is how to check as suspect something is open, but not sure which opens and closes points. Would like to use or replace guts but not sure if any specific voltage-amps needed or sent for this thing to operate. If just any 12V coming going would work, that makes issue a lot easier, but do not want to screw up other items this thing seems to drive. Yes it is the one in center on "relay bracket". Really odd that no one makes them as others are available. Will open it up tonight, kind of holding off until I can find out if others might be available.

1978 280Z manual, 2 seat. I have had a continued problem with "systems on" AKA fuel pump runs, volt charge lite on, EFI relay goes on, when Key off. I first tested all EFI (under hood right side box) relays, all OK. Check alternator which was new-OK, seat belt warning lite ON, unplugged harness, checked key switch-OK. Removed key switch harness, still got same systems showing "ON". Would run down battery in few hours as fuel pump remained running. Note even with full charge volt meter reads low (4-6) but will creep up to 12 plus over time. Charge light remains on. Finally printed blown up FMS electrical skew's, ONLY common to all this stuff, more so with ign switch unplugged from harness is the "Ignition relay" must be the issue, as only common to all according to FMS diagrams. The PN on Part, 25230-89958 below that M$ 3S-561. Saw when others went after this part Nissan dealer said rolls to B5230-W0500. I cannot find one any place, even on net. Have called local Nissan and they kind of said ho-hum not in stock etc. Does anyone know where to get one of these things and if so, what is the correct PN update? I suspect others have had same issues from what I have read, really hard to track down. is there ANY test for the part, as not yet opened it up to see if points burned etc. Suspect it is fault as for a while all was well if key shut off/on a few times, then went into 'come on 5 minutes after turning off mode, ran down battery if not checked. then finally failed as now simply runs. HELP please as ole yeller needs some road time.