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My 720 Resto


720inOlyWa

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I cannot remember what size the nut on the back of it is, if the intake manifold is removed, it's a lot easier to get to, and you have to know where the wrench needs bent before you can bend it.

It's likely the flex head wrench/crescent wrench is to fat, there is hardly any room back there. 

Here is the sensor on my work truck LZ23 engine(Z22 block) just in front of the starter, as you can see, it is tight against the block, imagine a napZ intake manifold over it and you can get an idea about how hard it is to get to.

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I had to replace my oil pressure sender on my '85 standard cab, and I found two things that help:

1) go in through the passenger wheel well.  There's a thin, rubberized material that separates the wheel well from the engine bay, and it's just held on with some trim clips.

2) Remove the oil filter.  The nice thing (at least for this; not for restarts) is that the filter is turned down and has a check valve, so it will be empty in the morning.  Just twist it off and you shouldn't get any oil leaking out, but it gives you a ton more room to move and to swing the wrench.

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Very helpful stuff. And wayno, I would sure like to cut a deal with you for that pigtail! It makes me drool just to see a pic of the damn thing!

 

I can’t let a day pass without doing something, so I rehabbed my valve cover, repairing the stickers, taping them off, and shooting a couple coats of satin black on there. Looks nice, but hardly worthy of a photo, if you ask me.

 

Did I mention that you really have me by the balls, wayno? Me want pigtail! Holy cow- what’s it gonna take?

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“....The nice thing (at least for this; not for restarts) is that the filter is turned down and has a check valve, so it will be empty in the morning....”

 

 

Is this why I can hear the cam tree rattle just a little for about a second or so during cold starts in the morning? 

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24016- there it is on wayno’s pigtail!

Hey I actually pulled the correct part number off of the tiny and confusing schematic!  The parts places list it at 37 bucks, but none can actually sell me one. I guess I can’t blame them for being out of stock...

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I had to pull my heater today because of a bad heater core so I decided I would look for the gauge pigtail while the heater, AC evaporator, and heater blower motor box was pulled. I would locate the main harness connection plug for the gauges.

 

Here is what I found so far installing my oil pressure gauge and volt meter combo today.

Main Harness plug wash taped up with blue tape behind the AC evaporator box.  I plugged the splitter pigtail into the main harness plug.  When I get the new heater core installed I will put all the AC and heater parts back together,  and I will finish installing the gauges.  My 86 King Cab only has 1 wire going to the charging light sender, but I think the other wire is there as it shows to go thru the plug on the passenger side fender by the battery.  The 2 wires required for the gauge type sending unit are a Yellow with Blue Stripe and a Yellow with a Green Stripe.  The Yellow with Blue Stripe was connected to my old 1 wire sender for the charging light .

 

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Gauge type sending unit with pigtail.

 

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Thanks so much for this, Charlie.

I love the way you find that blue tape and know you are onto something. And all of my blue tapes were so carefully wrapped, too.

 

Thanks to wayno, my pigtail is arriving tomorrow. I can hardly wait to go mining for the blue tape... (Actually, I think that I found it on the first go around- I just didn’t recognize it for what it was.)

 

Great job on the heater core. And thanks for posting these photos, too. Very helpful info.

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I installed the volt meter and oil pressure gauges today. What I found on my 1986 720 King Cab2 WD 5 speed Z24 California emissions was the yellow green wire did not exist in the engine side of plug #28 (this is the larger grey plug by the battery), but on the main harness side of plug #28 all the wiring is there.

I had an old 720 4x4 Harness that was bad that happen to have the wire I needed to ad to my engine side of plug #28. After adding that 1 wire and changing out the soil pressure sensor every thing works.

The idiot light sensor wire is YL (Yellow Blue). The Oil pressure gauge sensor uses the YL wire plus a YG (Yellow Green) wire.

Be careful not to get the wrong wires as the temp sensor also uses a YL (Yellow Blue) and a YG (yellow green) wires. These are in the smaller plug #27.

I pulled the engine/trans harness out and completely unwrapped it to be sure the wire was not there

I did not take pictures as I did it today.

 

The Plug reference #s are taken from the Nissan Factory Service Manuals.  I have a 1985 & a 1986 720 manuals.  Both manuals show the same.

 

Unfortunately I do not have a pdf of these manuals so I could not include pictures of the factory manual diagrams.

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Just got back from a shakedown cruise with the wife and dog to Orcas Island for the last three days. I was getting Ratsun withdrawl!  The Fudgecicle performed flawlessly, of course. (Well, there is always something to do...) Anyway, the oil pressure sensor is arriving (new one) tomorrow. Then I begin the last push on the guages. I bought a new filter and some 15/40 Delo too, so we will do the whole sheebang in one sitting. I am kind of excited that there is yet one more blue tape easter egg hunt to go. So far, any bamboozlement has been on me.

 

The harness has given up it’s secrets and treasures just as you all have suggested, so my money is that whatever I need for the oil pressure sensor will be waiting there for me. This is a late 1985 720 King cab, so I think I got the pretty late stage of development n this specimen.

 

If the weather is even slightly good tomorrow...

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So I finally scored at my jy on the oil pressure and volt gauge!! I already knew what I needed to take (at least I thought I did). Well I plugged it all in and sure enough the oil pressure gauge wasn't working. I knew it wouldn't but I just plugged it in to see it light up. lol

 

Now for my problem. I know now I need to get the right sensor. But from what you guys are saying it almost sounds like there's a separate harness from the sensor to this #28 plug in the engine bay.

 

Sorry to thread jack but I just wanted to know what all it is I need. I haven't done any digging yet in the engine bay but I will.

 

BTW, I check your thread all the time and your trucks coming along great. Digging your interior

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Hafa Adai, Guam.

No problem jumping in here- I am trying to learn the same things you are!  And, like you, once wayno‘s gauge pigtail showed up here (the infamous part #20416), I ran out and plugged it right in, just to see the volt meter come to life and the gauges light up. But the oil pressure was not working yet. Then, we headed out for the weekend. Now, I really need to dig into it, and get things hooked up right. I tell ya, I was absolutely thrilled to see all those totally stock, totally analog, totally important gauges light up, too. It really looks great from the driving position!

 

Which gets me to a diversion. I bought this truck out of the blue. I was really looking for a 520, or a 521, or maybe another 620 like the one we used to own. I just wanted a little four banger japanese truck again and, like everyone, it would be nice if it had some of that vintage japanese iron vibe. Until I met my truck, I didn’t even know what a 720 was. I remember thinking, when I first saw it, that it was just in too good of shape to pass up. But at the time I was disappointed that buying it probably meant I would not get my 521 to restore. This one would be ‘it’.  My best friend Brian, another lover of small japanese trucks, immediately nicknamed my 720 ‘Gerald Ford’ due to the blockhead blandness of the styling. He meant it as a loving joke, of course. He dug it hard, even before I really did.

 

Well, no disrespect to my friends driving ultra cool 521s, and 620s, but now, today, I am really, really glad that I am a 720 guy. 720s are it, if you ask me. I love the styling now. LOVE it. Just sitting there with the full suite of analog gauges lit up, and the clean and sensible dash layout before me, driving along effortlessly with the power assist steering and those disc brakes... And the room- holy cow- King Cab roominess!  I have to say- to me- this is a distinct improvement over the 620 that we owned and loved for many years. It just is. We even hauled a gnarly five foot piece of driftwood home from Orcas Island, to be put out in the garden somewhere.

 

When I bought this truck, it had overheated, etc. I think this probably destroyed the original oil pressure sensor and so when I got it running again, it really leaked badly out the end there. The sensor had failed and my driveway had the oil stains to prove it. So I replaced the sensor and, as a result, this engine does not leak a drop of anything, anywhere. That was the final element I needed to tighten everything up, engine room-wise.

 

That experience made me twitchy about used oil pressure sensors (probably needlessly), so I ordered a new one from Rock Auto before this little trip over the weekend. It arrives today and once I have it in hand, I am gonna re-read everything you guys have to say about your experiences hooking it up and finding connectors, so it will be a snap for me. How‘s that for strategy, eh? Nya, Nya, Nya!

 

Up on Orcas Island, the locals wave at you or nod if you are driving a little goat hauler that is anything like theirs.

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You might have the wire/plug taped up in the harness, if you don't, then you will just need to do what Charlie did and just add that wire into the harness, you would just splice into the pigtail and then plug it onto the sensor.

I cannot remember which sensor connections are which, it's a "T", one is for the oil light in the dash, the other is for the gauge, Charlie knows, it's been a while since I did any of this.

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On the 85 86 2wd king cab the pigtail that connects the plug #28 to the oil pressure sending unit is missing the second wire for the oil pressure sending unit for the gauge.  The main harness side plug 28 has both wires.  You will need to ad 1 wire and change the end connecter of the existing wire from a bullet type connector to a female spade type connector.

 

I will try to get some scanned images of my FSM and post them.

 

Best money you can spend on these trucks is on the Factory Service Manual in my opinion.

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So thankful for your help, Charlie.

Yes, the shop service manual was the first thing that I bought off of ebay.  I bought the Haynes, too, just for a cross reference / second opinion. But the shop manual is my go to guide. It’s a good book.  But I don’t have my official 1985 720 King Cab owners manual yet. Sure would like to have one of those, too. It is pouring down rain outside, so no truck work today. Instead, I am going to ‘organize’ my garage so that at least one bay is available to bring it in and work on it. I have big 720 plans for the winter and I dont’ want to stop because of the weather.

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I have all but removed the dash out of my truck over the past two days, searching for the elusive pigtail connector plug. Yesterday, for a couple of hours, and again this afternoon, I contorted my body into positions that I have not assumed since I dated Roberta Cummins, looking for that damn plug connector. I used mirrors and flashlights, fingertips and radar and anything else I could get my hands on, but there is just nothing to be found there. At least I sure couldn’t find it. If it is there, it would have to be on the firewall side of the defroster vent, taped into the harness with the black tape, not blue. There is just no blue tape anywhere in the target area, period.

 

It seems bizarre to me- impossible, even- that I would have a clock and tach plug, but no voltmeter and oil pressure plug. It must be up in there somewhere where I can’t see it at all, or this harness just didn’t have one. The answer will have to wait until I am up for the full dash removal project and right now, the only reason to do that is to find the fucking plug connector. So, short term, I will have to seek alternate wiring solutions if I want these gauges to go (and I do).

 

I think I will go outside and put the 15/40 Delo 400 and a new filter in her. I can’t possibly suffer another defeat in that effort, right?.... 

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