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Oops, I did it again!


720inOlyWa

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Before I do my little victory dance for the day, I have a couple of little ‘mystery‘ problems that I would like to bounce off of you. 

 

1. There is a toggle switch on the face of the console that obviously operates the fuel pump.  With the key on, you flip it and you can hear the fuel pump come to life. This is some kind of jerry rigged bullshit. Does this suggest that at some point the ignition switch wore out, so they bypassed the non-working fuel pump circuit? Once on, the fuel pump makes a noticeably louder clicking noise than my other truck which makes me wonder if it isn‘t supposed to have less than 12 volts directly to it. Any thoughts? The organ donor 720 that I bought some time back had a similar junker bypass wire to the fuel pump so it put me in the mind of thinking this is a common injury.

 

2. there is either a giant bumblebee trapped behind my glovebox, or some kind of relay is really upset when it is running. Whenever the truck is running, it buzzes loudly and constantly. Any suggestions?

 

There is something fascinating about bringing an engine back from the dead. It is often either slightly reluctant, or really reluctant to come back to life. Today, I went through the process in earnest, struggling through a couple of small fire drills to attach this, change  that. The oil filter was the wrong size, so I got to pump half a quart of Delo 400 onto my driveway, which was no fun. But in the end, I won and this engine is running real nice now. It has, at the end of the day, resigned itself to having a new life.  

 

I dialed it in to the timing marks at 800 rpm and it just ticks away like a sewing machine. Very smooth and even. Tonight Iam thinking that little the Z20 is pretty cool stuff! Of course, everything from the back end of the muffler to the tailpipe is gone, so it is a little louder than I like. But a trip to Eddies Blue Flame Automotive for a Honda accord muffler (and probably a brake job) ought to set things right.

 

Despite the fact that I haven‘t applied for title yet, I was tempted to go for a little test drive. But when I sat in the drivers seat and pressed in the clutch, it had little resistance to the floor. Either the clutch cylinder or the slave cylinder is funky and until that is addressed, it aint going anywhere.

 

But today, ‘Fitty Buck Chuck‘ officially crawled out of the crypt- reborn!

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Who needs a clutch for a test drive?  :thumbup:

 

Doing good, I am always impressed by your work.

 

There is an actual fuel pump relay, or you can always just find something hot in the fuze box and tap. B)  My first fuel pump in the 4wd clicked like a really clicky thing, but I got a U.S. made one that was the right PSI and it makes a nice wooshing sound.

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2. there is either a giant bumblebee trapped behind my glovebox, or some kind of relay is really upset when it is running. Whenever the truck is running, it buzzes loudly and constantly. Any suggestions?

 

https://axleaddict.com/auto-repair/The-Datsun-and-Nissan-Pickup-Fuel-Pump-Relay-What-the-Haynes-Automotive-Repair-Manual-Wont-Tell-You

 

2238119_f520.jpg

 

Sounds like the PO tried to bypass the electrical supply to the fuel system

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The article on the fuel shutoff relay sounds like it is exactly what I am up against. So thanks for that link! While I get ready to pull the relay, I am finishing up some engine bay details and getting ready to test / pull the clutch slave cylinder. Trusty assistant stands guard, of course...

 

 

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Clutch Hydraulics Overhaul

Today, I began diagnosing the problem with my clutch. There is no resistance in the pedal, save for the return spring. The slave cylinder isn't moving and the bleeder at the clutch damper doesn't drain fluid when the clutch pedal is depressed. My suspicion: dead clutch master cylinder. Still suspects; the slave and clutch damper. 

 

To take it all apart, I took a 10mm box end and sliced it open on one facet to slip over the hydraulic lines. Then I shot all the little rusty nuts with penetrating oil to soak overnight.

 

As with other critical systems, if one part dies, the entire system needs an overhaul. So I will remove, inspect and repair/replace all needed clutch parts. The paperwork I found in the glove box indicated that the truck got a clutch and throwout bearing and a rear engine seal 4,000 miles ago. For now I will keep fingers crossed that the clutch itself is good.

 

Reading the NSM and Haynes, it seems rebuilding the hydraulic components is expected over replacement. I will search for rebuild kits once I know that the cylinder bores are still intact and/or honeable. It all comes out in the morning. 

 

Any tips on where to buy rebuild kits? Nissan Parts Zone? 

 

By the way, Grandpa Truck Rules say if the clutch hydraulics are funky, how good could the damn brake hydraulics be? I haven‘t even tried the brakes yet, but with this in mind, they will get the hairy eyeball a little later. I already have a fresh brake booster in the waiting room, gleaned to replace the rusty one in this truck. It would be nice to know that all of the hydraulics- simple as they may be- have been completely refurbished.

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I can officially start complaining about the heat now that it is getting too warm to lay in the driveway for a long period of time. So I took on some of my favorite ‘inside‘ work instead, rebuilding the dash cluster and rebuilding / rehabbing the drivers side seat. I replaced the non-working fuel gauge and added a tach and (beloved) clock. Interesting that in 1984 it appears you didn‘t automatically get a trip odometer... or was it an option? You would certainly expect that an ‘MPG‘ model would have a trip odometer, if they were available. My guess is they were ‘new for ‘85!‘.

 

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Interesting that in 1984 it appears you didn't automatically get a trip odometer... or was it an option? You would certainly expect that an ‘MPG‘ model would have a trip odometer, if they were available. My guess is they were ‘new for ‘85!‘.

 

 

According to my little book of Nissan Trucks from 1984, the only trucks that came with a trip odometer standard were the King Cab XE (2wd), ST, and all 4x4's. 

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Hard to believe that it was an option! Geese, c‘mon, man. This truck had no jump seats, delete panels in the dash cluster,  no A/C, PS, or wheel bands and no trim at all (except for some JC Whitney added later). And no trip odometer. This must be a absolute base level KC. Fascinating to me is the fact that it did come with a beautiful NISSAN bed pad- certainly an ‘extra‘ as I have yet to come across another.

 

I have to say, even back in the days when I collected 49 Plymouths, I loved finding a spartan base model, simply for the opportunity to examine the austerity level that people would choose back in the day. No trip odometer? How does one decide to forgo the trip odometer option? Well, it must have been another $34.95. I would‘t necessarily do this, but I know people who buy a vehicle purely and simply on how low they can get that final price. I am told dealerships often keep a couple of super cheapie stripped models just for this kind of sucker to discover.

 

My dad, who generally modeled bad behavior in most respects, did teach us how to buy a new car correctly. I will never forget seeing that fat salesman trundling ever faster across the lot as he recognized that dad was writing a check on the hood of a pumpkin colored Datsun 620- the cheapie on the lot that nobody but the cheapie suckers would want. By the time we left, that truck was loaded- even had mag wheels, tape deck,  and a tonneau cover- and the check he wrote was for the cheapie sticker price in the window.  

 

That is how I ended up with a pumpkin colored little standard cab 620. The color was horrible, but the truck was an absolute burro.

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Wayno got me to thinkin’, as he so often does...  

So I said to myself: “Why not throw one of your trip odometer speedos into that gauge cluster, and to hell with the 30k less on the main odo?“ Once I made sense of the question, I decided to swap another, slightly later model speedometer into my cluster. So I did that this morning. Thing is, there are two plugs coming out of newer speedometer and I am a little confused about them.

 

I can find the connector for the purple and black plug, taped up onto the harness with blue tape, but the red and yellow lead is still a mystery to me. I can‘t find a plug for that one. any ideas where it goes? For that matter, as I look at the gauge, I cannot understand what either of these plugs actually do. Any information would be appreciated.

 

YVyLTth.jpg?1

 

Removing the gauge cluster reminded me that I saved one of my wrecking yard donor clusters where I just cut off the plugs and speedo cable to get it out. Leaving these attached this way gives me an excellent instructional tool to use when removing this one in the truck. I can ‘rehearse‘ how to remove / install each plug by having this one on the seat next to me. It actually helps because I forget how I got it out once I am done with that project and have moved on. And there is a little sequence trick to pulling a gauge cluster: you must unplug it from left to right.

 

This little tool helps me remember the sequence and the way the plugs orient to the board and how they unplug/plug in. Oh hey, lookie there- the purple and black wire plug is taped onto that plug lead. How convenient!

 

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Good guesses, I am sure.

30,000 sensor makes total sense as I looked at the the way it is integrated into the gauge itself. Cruise control? Interesting! The instrument itself is purely mechanical, so I was going to use it in any case. But if I can plug something in, well I am all for it. Which highlights my low level of electric circuit confidence and understanding. To keep things as simple as possible,  I have decided to leave the dash cluster out for now, and to remove the center console and the toggle switch for the fuel pump as well. Whatever can come off, is coming off for now. 

 

I figure that if I can expose as much as possible, it may become obvious how to restore the wiring to the original configuration as I repair / replace the fuel shutoff relay and rebuild / replace the clutch master cylinder.  It looks pretty clean behind the dash so far, with only a couple of wires deviant from the stock harness. But I have only begun diving into it.

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We had a nice, cool cloud cover here in Olympia, Washington this morning. That made removing and rebuilding the clutch master cylinder a rather pleasant job, so I dove in.

 

When I pulled it, I was not optimistic about a rebuild. it was pretty crusty around the plunger rod and the piston was clearly stuck in the fully depressed mode. But as it so often is with these things, a Harbor Freight wire brush and some elbow grease made things look more optimistic by the stroke.  By the time it was all apart in my hands, it became clear that it was simply mucked up and jammed with broken down brake fluid. After a thorough cleaning and inspection, even the rubber pistons showed no signs of wear once they came out of the fresh brake fluid rinse off. So I just cleaned everything thoroughly with brake fluid and put it all back together. Ditto with the damper and slave cylinder.

 

When I began, I thought it would be an all day job, and that I could possibly be facing replacement of the three hydraulic components of the clutch. Instead, I did‘t even have to replace any rubber parts and I was done in about an hour. A thorough cleanup and bleed was all that it cost to get the clutch hydraulics back in action.

 

As a result, Fitty Buck Chuck rolled under its own power for the first time since 2010. Sure, it was only a circuit around my circular driveway, but I got to try out the clutch, first gear, and reverse and all three worked smoothly. Another domino falls.

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Surfing a bit of a progress wave, working on Fitty Buck Chuck over the past few days.

With most of the dash pieces removed that can easily be removed, I traced the wiring alterations for the toggle switch and the fuel pump. Turns out the lead was just a fork connector jammed into a hot lead in the fusebox. Who would go to the trouble to install the toggle switch and then just stuff the lead wire into the fusebox? It made me realize that this entire toggle switch to the fuel pump bullshit was a fix for an intermittent problem. I pulled the wire out of the fusebox (it fell out, honestly) and the truck started just fine. In fact, the screaming fuel pump relay stopped for a few minutes as the truck idled to temperature. Then it started screaming again. I bet that if I drove it out not the freeway, it would quit on me. 

 

Clearly, the bad relay made the truck cut out and this made it unreliable to drive. The direct line to the fuel pump via the toggle switch was the stopgap to get it to startup again if and when art croaked. I think that it will all work fine again once the relay is repaired or replaced. I drove it around my driveway and up and down my street and it is pretty stiff steering. I made a mental note to give it a lube job, check the steering box for fluid and get some skinny tires for the front.

 

While it was running, I tested the fuel gauge and the tachometer, to see if they were working. The clock was ticking away nicely, so it works fine. But the tach didn‘t come to life. I remember something abut adding a resistor to make the tach work, but I forget the specifics just now. But I know that is on my other resto thread, so it will be easy digging to get to it.

 

Gotta have that tach up and running too! 

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Why Ratsun is so effective...

During my first 720 rehab project, I added a tachometer and clock and it is amusing to me to re-read my trepidation's regarding finding this plug or that. They are all there and finding them is second nature to me now. as I was completing that install, I was fretting about a resistor and whether or not I was going to need one to make the tach work. This lead to several good responses about what to do, and a link to a previous thread in Ratsun about this vey subject- supplied on my thread as a means of getting me to the good information quickly.

 

While at the wrecking yards, I began collecting little resistor plugs like crazy there for a while, hoping that one or another would be the one that I needed. As it turns out, my first truck already had the resistor plug, hidden up under tape near the headlight. Now I had a little Nissan resistor stash.

 

Fast forward to today and Fitty Buck Chuck is getting a tach and clock install. Sure enough, on this economy model, they didn‘t just wrap the resistor up in the harness. The plug was empty. I went fishing in my little resistor stash and found just the ticket! Boom- the tach works fine now and another little domino falls. Point being, I had a clue going in, thanks to Ratsun. I knew what to go collect, thanks to Ratsun. And a rather tedious task that could have stretched out over days and cost more than a couple of bucks was, instead, a fun 20 minute job, including coffee- thanks to Ratsun.

 

I don‘t say it enough: I sure appreciate all the help.

 

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The truck steers like a tank, and this furrows my brow a little...

The ‘power steering versus no power steering‘ debate creeps back into my thoughts. I have only driven around my circular driveway a few times, but it really takes some muscle to turn the wheel. This means nothing right now, however. Before I freak out, I need to jack it up, lube the front end, check the oil level in the steering box and get some properly inflated, new tires on the front. If it still is hard to steer after that, then I will hit the panic button.

 

But this morning, I just did‘t feel like grabbing jack and the the slider and the grease gun and going under. Just was‘t into it. So, instead, I de-rusted and re-painted the rusty window frames on both doors. If you live on the coast and you are familiar with 720s, you know that that black paint bakes away over time and surface rust can get a foothold. In my other resto blog I outlined my procedure for dealing with it; 220 sanding, Metal Prep, Rust Out primer, followed by two coats of 2X Rustoleum satin black. That repair is holding up nicely after two winters outside, so I guess it works fine.

 

Here we are after the sanding and Por15 metal prep, ready for primer and paint:

 

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And here it is after two coats of satin black:

 

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Already, I wonder if I should have used VHT charcoal engine block paint instead. Oh well. I will quit the profiling and get back to the grease gun work tomorrow... But you have to admit that it is also fun and satisfying to banish the ‘shabs‘ once in a while, too.

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Z20 engines...

Just finished reading the Wikipedia section on the 720 truck again and I was surprised to see that the Z20 engine is a bit of an odd duck. It says that it only came on the 1981 MPG version, but this is a 1984 truck. Although I can find zero evidence that the engine was ever removed, maybe it was done right and I just can’t see it. Either that, or the Z20 engine was available on 1984 720s as well. 

 

The Wiki description mentions a ‘knock sensor’ that advances the timing. I wonder where this is and exactly what it does.  Are there management issues related just to the Z20 that I should know about? For sure this engine has the dished truck pistons.

 

hZQjtPn.jpg

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Im not sure, Charlie. Ive been under there, but I haven‘t really looked over the sway bar. There big, bent rod like fellow up there under the front (sway bar?) is just like my other 720 2wd.

 

Im to sure what the gear ratios and sway bars have to do with the Z20, but I am all ears. I will check that out, too. Main thing that concerns me is this “knock sensor” talk and how it advances the ignition. First that I have heard of any of that. It looks like a regular old Z motor to me. If there is something advancing the ignition by 10 degrees, I need to know about it.

 

Back down to earth: Today, I am going to remove another thorn from its paw by replacing the plug wires. 7 out of 8 are original to the truck. It all adds up.

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