Zed Head

Think about converting back to stock. I don't know if the conversions involve permanent changes. I thought that they were just bolt-on pieces.

Good luck with that. Might want to see the cylinders, if you can get them apart, before you buy the rebuild parts. Pretty crusty.

Look at BE-94 in the Body Electrical chapter. Nissan really didn't label the chapter sections well. You have to stumble upon it.

There's a dirty crusty plastic panel inside the fender well that you have to remove. Easiest with the wheel removed.

This is not precise enough. You need the numbers. Yarb makes a good point about things that might be getting stuck. Buzzers, light switches, corroded relays, corroded switches. For example, the dome light has constant power. The light comes on when the circuit is grounded, either by pressing the light itself, or when the door is opened. The switch is in the door jamb (I think). You could also try pulling fuses and watching the current. Eventually you'll find the circuit or circuits that are passing the current to ground. I did take the time to look at the diagram and see that there is a lot of stuff that has constant power. And lots of connectors. Really looks like a PITA. The black and white diagram hurts my eyes to try to follow. One blink and you have to start over. That's why being methodical and taking good notes will really help.

Break it down in to pieces. CO narrowed things down above. Keep going. The most important finding so far might be that the problem is not a simple "replace a part" problem. Saved $30 on that VR probably.

Thanks Captain. That was kind of in the back of my mind but I didn't follow it out. With the wiring diagram and the knowledge that there must be a path to ground that is not supposed to be there, there are many ways to narrow things down. Even a meter set to beep mode. Unplug connectors and probe pins for paths to ground. Unplug connectors and watch amperage.

The four barrel conversion is probably easier to tune and might be more heat resistant. They've been around quite a while you can probably find them on eBay or CL. You could even a 2 barrel adapter on it. https://www.thezstore.com/category/498/four-barrel-conversion

I was thinking of blocked passages in the head gasket. I'd probably back flush the system myself, if I was reasonably sure that everything else was right. Push any blockages back toward the water pump and out the inlet. Disconnect the radiator, hook up a hose to the thermostat housing (outlet port) and see what comes out.

This is odd. Kind of implies that you're wiggling a wire when you're removing the link and removing the short. Can't think of how disconnecting the two separate fusible link circuits separately could stop the draw. Weird stuff. It started with removing the VR lowered the draw, then both alt and VR out still had a low draw, now disconnecting either fusible link separately removes the draw. One problem with your posts is that you leave things out in your descriptions. Like in the post above you said either link disconnected removes the draw. But you didn't confirm that the VR and alt are still disconnected. Plus you don't give the numbers. You've had numbers from 0.2 to 3 amps. It would probably help if you made a table showing the numbers with each condition. VR alone, alt alone, each fusible link, combinations of each. Actual numbers.

Have you ever had the head off?

I was making a general point. Where will you go from here? What does your old Z mechanic suggest? Maybe you really just have a hot spot by your temperature sender. How about that?

The bottom line is - if the cooling system can't cool with no thermostat it will never cool with a thermostat. You're probably spending your radiator money on thermostats that you don't need.

The thermostat is actually opening and closing continuously during operation at designed operation temperature. If it just opened fully and stayed open there would be no temperature control.

They're all the same I think. The internet multiplies the population of potential victims. The internet makes conning people much much easier.

I hadn't thought about the old Google Maps. It's usually one of my go-to's. https://goo.gl/maps/nukesb6RXc6yStYc6

Have you done this, to confirm that more flow will actually solve the problem?

How are you measuring the draw?

Went back through your posts and see that it's not really clear when the draw occurs and/or how much. And, my memory of a current draw I had was that even 0.3 amps will kill a battery after a day or two. So, you have a draw with both the VR and alternator disconnected. How big? Fluctuating does not tell enough. How many amps or milliamps? Seems like you might have a short in the wiring and the short is to a wire that passes through the VR and/or alternator. My wiring harness in the engine bay had some melty looking wires in it when I unwrapped it. Something had shorted in the past and heated them up but they survived.

p.s. also measure from the VR case to W. The case is used as ground according to one of the previous drawings. They show the meter between yellow and the case.

W is connected to the battery through the fusible link. Signs are pointing a short to ground inside the VR. If it was in my hand I would measure resistance from the W pin to the B pin on the VR, with it disconnected. That would be where the path to ground is.

The field wire is connected to ground. The short is inside the VR. The path is not as long as it's supposed to be. With the key off. We can argue semantics but the test is valid.

You need a simple but effective test. The "click" is not it. Looks like you know how to measure amps. Set up your amps measurement and disconnect the two wire plug at the alternator like SteveJ said. No need to identify wire colors or look at diagrams. Then you'll know if there is a short to ground through the F circuit of the VR. Make sure the key is off.

These guys are still business. The Z's look a lot better though. They had a few that came straight from the wrecking yard for way too much, in the past. https://www.beverlyhillscarclub.com/inventory.htm?make=[Datsun]&orderby=make,year

That's not a bid, it's a price. Looks like a consignment shop. The cars are all in different locations. Sell, sell, sell... https://www.ebay.com/str/exoticcartrader