Zed Head

Remove this cover. You''ll probably see the wires.

I think that Leno just likes being in the limelight. That's why he unretired. The Evans product is a product. It's for sale. They have to sell to keep the business alive. Always keep that in mind when you're looking at the claims. Here's the rationale behind the 10% MPG improvement. Reduced alternator load. https://www.greencarreports.com/news/1071361_waterless-coolant-improves-engine-life-boosts-mpg-10-percent I just watched the video again and Leno says that he really doesn't know much about cooling systems and he only runs the Evans in one of his cars. He owns 159. I watched a little more and realized that he doesn't maintain his own cars. He has people that do that for him. He's a guy with money that likes owning cars. Sorry, no offence intended. I don't see any sign that he really knows much about how engines function, let alone cooling systems. His rationale behind the corrosion of the aluminum plate on his Duesenberg is simplistic. He also said he didn't use the Evans on the Duesenberg because the "higher boiling point could affect the metal". Nonsensical. It's at 40 seconds in the video. Again, sorry to pick on Leno. He might be a successful comedian but he's not anywhere close to an expert mechanic. He has people for that. Here is an example of the depth of his advice on buying a used car. https://www.cnbc.com/2019/09/10/jay-leno-do-these-3-things-before-buying-a-used-car.html

And, any typical antifreeze has corrosion inhibitors. The Evans system always seemed like an expensive last resort to me. For the racers with overheating problems. https://prestone.com/ There have been some interesting discussions over on Hybridz about it. TimZ has a high horsepower engine and uses it. Put these words in Google - site:hybridz.org evans timz

Jay Leno is just a rich guy with expensive toys. No reason to think he's a car expert. The youtube video is an Evans advertisement. Jay probably got paid. This part in the youtube description is a big BS flag - "increases your fuel economy up to 10%,"

Meter. Test light. What you need might be in this document.

They get power depending on where the switch is, I think. There's slow, and fast, and park. Find the pin on the motor that matches the B wire and that would be your ground. Ground that pin and apply power to the other pins and something might happen. I'd work through the diagram and description and pick a pin but that would be work and it's Saturday.

You should see power at the plug. Any chance you disconnected the intermittent amp? That's what controls the power. I think it's in that area where you were doing all of your relay work.

$41,750 for a 73. https://bringatrailer.com/listing/1973-datsun-240z-171

CanTech Z uploaded this 1970 FSM to the site a while ago, it describes the F4W71A. For whatever reason the 1971 FSM is oddly formatted but it has a chapter also. The 1971 document has the same description as 1970, so it looks to be the same transmission. The 1970 document is a clearer copy. https://www.classiczcars.com/files/category/11-240z/

Have you checked the action of the shift fork on the coupling sleeve, and the sleeve on the hub? I wonder if the sleeve could get cokced on the hub as the fork pushes it over. Like if one tine of the fork was ahead of the other. The sleeve should lock in, or center over its final position, but maybe you're getting incomplete travel and final engagement. You have it all torn donw now but you might find some sign on the parts. Maybe a loose fork on the rod. The roll pins do fail. Ideally, you would check the action by moving the shift rods with it mostly assembled. There are also the detent pieces in the adapter plate. The balls, springs, and pins that set the final position of the shift rods after a gear selection. Your description sounds like something relatively large wobbling around the shaft. If all of the bearings and other parts seem undamaged and correct then it seems like the parts must not be correctly positioned.

Not sure which side of the harness you're looking at. Remember that the switch harness colors probably don't match the main harness colors. Here's a better diagram.

You might read some of the Honda upgrade threads. People have dug in to the operation of the factory motor so that they can replace it with a Honda motor. There's probably a schematic in one of them.

Have to admit, the diagram is pretty hairy...

p.s. we used to build vent filters for our vacuum pumps that were about 8 inch lengths of two inch pipe packed with stainless steel wool. The steel wool collected the suspended oil and let it drain back in to the vacuum pump case, while the "cleaned" evacuated gases could exit. The same basic concept as the steel wool in the block side port in the Datsun blocks, I think. If I was going to run a vented valve cover I'd build something like that, concept-wise, to keep the area cleaner. It would probably be ugly, but might be effective.

If you want to avoid the fumes you'll have to run a closed system, like a PCV. So any vents under the hood won't work. Or you could run the vents to an area that is clear of the cabin, maybe all the way back the rear of the car. If you run a closed system it needs to be properly balanced so that you don't have high air flow through the crankcase pulling suspended oil out before it can settle. I've been hanging out on a Ford truck site and people get on there all the time talking about how they're pulling like a pint of oil a week in to their catch cans. Maintaining their catch cans turns in to a full time job. I think that the catch can system designers might be designing their system to pull a lot of oil. The people that have them want to see stuff in the can. If it's empty they'll think the can is not working. Even Ford has jumped in to the "upgrade" game but their system has to meet the PCV needs. It's more complex than the typical shiny metal can aftermarket systems. Interesting to study. Read the hype in the a copy. https://www.cjponyparts.com/ford-performance-oil-air-separator-kit-passenger-side-mustang-5-0l-2018-2021/p/M6766A50A/ https://www.cjponyparts.com/ford-performance-oil-air-separator-kit-gt350-gt350r-2015-2020/p/M6766A50K/ https://www.cjponyparts.com/catalogsearch/result/?q=+Ford+Performance+Oil-Air+Separator

There is bad information out there on the various web sites about the Z car transmissions. And the kits are incomplete. Here is where EuroDat got that drawing. Compare the part numbers and you might be able to confirm that it's the same bearing used in the later four and five speeds. Then use EuroDats's writeup to cross-reference. Click through the four speed page and you'll find the early 4 speed. You can probably find a cross-reference to the Nissan part number also. http://www.carpartsmanual.com/datsun/Z-1969-1978/power-train/transmission-gears

What is it? I can only see bubbles in your picture. Is that a welded seam or a pipe fitting? Seems like Quickjack is overly confident in their manufacturing process. A leak in a pneumatic system is a pretty significant miss.

I had a switch from a parts car that had a problem and I was able to fix it by restaking the pins on the back. I tested it with a meter, after I had already taken the car apart, then started wiggling the pins and found that one was physically loose. In the parts car, which I had running for a while, the starter would catch then let loose as I tried to start the engine. Very annoying. I thought it was the starter but it seemed to actually be the switch.

The Quickjacks were dropped in to your thread with no introduction. They look interesting. Is this them - https://www.quickjack.com/

I think that one of your adapter plate bearings is bad. I don't think that the shaft should move back and forth like that. @EuroDat @zKars @Dave WM

I thought he meant jump at the battery. It's sounding like he meant he jumped the solenoid, bypassing the ignition switch. More words would have helped.

On further thought I'm not sure about my post above. The sleeve and hub mate around the full circumference, the gear teeth mesh at a single point around the circumference. So a noise that changes with RPM would have to be related to the mesh point of the gears. I think. Anyway. Another quick way to get a look is to drain the fluid. The stuff that comes out will tell a story. Looks like you must have drained it, was there anything there?

Sounds like something on/in the coupling sleeve and hub gears. Could be a chunk stuck in the teeth or a broken tooth. The shafts and main bearings are all shared between and the gears themselves are constantly meshed so a gear problem should be heard all the time. Only the coupling sleeve and hub meshes when you select a new gear. Although, there is a needle bearing under each gear that might deflect under load. Others have more transmission experience. Seems like you'll need to take it out and apart though to know for sure.

Can you add some detail? Are you saying that the clunking rate is constant despite RPM? How can that be? Does it continue to clunk if you're in 3rd with the clutch pedal down, car not moving? Or does it only happen when the car is rolling? Clunk is not very descriptive, even with the awful added.