My '82 720 Diesel thread

[Slowas720]

Hey all, just this last week I was given an '82 720 King cab diesel by my employer, for free.

 

Long story short, I work at a very small dental lab and noticed the truck sitting out back and after a lot of asking about it he decided to give it to me as it was given to him.

 

I have a long history with cars, from Autocross and SCCA road racing to slammed cars and off roading. My first two cars were a '72 510 two door with a crazy built L20 and a '73 510 with dual 40mm Webers.

 

My plans are to kind of resto-mod this truck; honestly I know its gutless but I'm in love with it. It had been sitting since 2012, I put a new battery in and it fired right up, I drove it 20~ miles home and have started slowly tinkering. 

 

Like I said, I've put a 'new' battery in it. Noticed it was heating up and losing a little coolant so I pulled the cap and noticed it needed to be replaced and bought a new one. It also had only one wiper blade and the wiper arms were loose so I tightened them down and bought new blades.

 

Things I want to fix first:

1. My temp gauge was working before I replaced the radiator cap and now it seems that it doesn't want to anymore. Heat inside works, gauge doesn't ever more, even while driving. 

2. Driver side turn signals work, but only if you use the hazard switch on the steering console; the turn signal switch doesn't do anything for turn signals but the headlights part works and all lights outside come on. 

3. Radio doesn't work at all. Not really super important though.

4. Need to find new rear window latches; the driver side one is toast and doesn't latch.

5. Probably need to clean the heater and vent controls, they're a little stiff and the blower turns off when switched to '3'. 1 and 2 work fine.

6. E-brake is toast, can't pull it back and lock it or anything, it's useless right now.

 

Heres some photos of it before I got it home. And a photo of the new and old radiator cap.

 

[wayno]

Welcome to the Datsun diesel world.

There are a couple wires below the thermostat cap on the driverside, one of them is for the temp gauge, make sure they are connected and maybe clean up the sender spade.

As for the e-brakes, the cables have likely rusted solid, you can get under the truck while someone else pulls the e-brake on and see what moves, then remove that cable and see if you can free it up, all kingcab cables are the same so you can likely find a cable in a wrecking yard to replace the ones that will not move.

I am not a fan of the SD22 engine, my first 720 SD22 diesel got really good mileage around town(25mpg), but on the freeway it was gutless and drove me crazy(27mpg), I moved on to the SD25 engine which was slightly better, it got 25mpg/28mpg on the freeway going 70/75mph, and then a couple years ago I finally figured out how to turbocharge my SD25 engines without issues, I went to 25mpg city/31mpg freeway going 75mph.

We turbocharged my friends SD22 engine but I was not impressed, but maybe the turbo was not the right one for the SD22.

You need to clean all the contacts in the turn signal assembly and the 4 way assembly, that may get them working.

It appears the cap on the right has the rubber piece on the end when the old cap does not, I would use the old cap way as that doesn't build up pressure in the water jacket, and the coolant just expands and fills the coolant reservoir instead of blowing holes in the radiator/hoses, when they sit a long time stuff degrades.

[Slowas720]

The radiator fluid wasn't filling the overflow at all, it was coming straight out of the cap and spilling over. 

[620slodat]

Cheney sounded familiar, so I looked it up on a map. It's located just west of Spokane. When my Grandfather was still alive we went up there several times. Still go up there occasionally to visit cousins in Spokane and Post Falls, Idaho. I like that area.

 

The next to last pic in your post will be very helpful to me. Having a pic of a stock engine bay is good for me as I am very slowly putting an SD-22 into a 620 pickup. I just need to figure out why most pics in each thread are fuzzy.

 

You should get acquainted with Wayno (on this forum) as he has several 520/521 pickups that he has converted to SD-25 diesels. He lives in Vancouver, Washington and is very knowledgeable about the SD motors.

 

Don

[620slodat]

Looks like Wayno beat me to posting. Hunt and peck typing is slow.

 

Don

[Slowas720]

I actually just moved to Cheney from Post Falls this last July. I like this area as well, I spent two years in Minnesota and couldn't stand it, lol.

[Slowas720]

Went to go start it yesterday and thought the battery was dead, hooked it up to a charger and it was fully charged. Come to find out that my starter is kaput. Gonna buy a new solenoid and hope that fixes it, for half the price it's worth a shot. 

[wayno]

How did you determine your starter/solenoid is bad?

Is the starter already removed already, if not get yourself a large flat blade screw driver, there are 2 large posts on the starter solenoid, using the screw driver tip bridge the gap between them two posts and see if the starter works, I have started my diesel truck so many times this way that I don't have enough fingers/toes to keep count, next with the screw driver jump from the main battery connection on the solenoid to the starter exciter wire post and see if that gets the starter turning, if it will not turn over that way then clean the battery cable post at the battery and the starter and try again.

For some reason the wire going from the ignition key to the starter can lose voltage and the power that actually makes it to the starter is not enough to activate the starter, on one truck I had to put in a relay near the battery that gave the starter exciter wire a full 12 volts because the wire that was supposed to work didn't have but 7 volts, that was enough to activate the relay and the starter worked great again.

I would always have an extra starter on hand if your going to keep this diesel truck, I would also find another alternator/vacuum pump, transmission, DPC module, injection pump controller, and glow plug timer, it is a bitch when one of these things goes out and you don't have a replacement.

[Slowas720]

So, the 720 has sat for a little while. I went out and did the screwdriver trick yesterday and it sparked a little and tried to engage but I think the battery was too dead. Charged the battery up and put it in and now I get really dim and erratic dash lights and a fast clicking noise on the passenger side. Engine doesn't turn over and the dash lights disappear when I turn the key all the way, clicking only goes away when I turn the ignition off completely or when I touch the screwdriver to one/both/any of the starter solenoid terminals and the body of the starter.

 

Wondering if I blew a fuse or relay or something? Other than touching the starter solenoid terminals with the screwdriver and charging the battery, nothing else has been touched or done to it.

[wayno]

The first thing that comes to mind is when stuff starts acting weird like your talking about, clean up the battery posts and connections, I have even had to clean up the battery cable where it connects to the starter before, that is a long battery cable also, they can go bad, but I am thinking since you got it started and drove it home that battery cable is not the issue, clean up the battery connections real good.

You said you have been tinkering with it, have you added anything else like gauges, anything to do with wiring?

 

Also do you know how to check the fusible links?

Edited December 12, 2019 by wayno

[Slowas720]

No, I haven't added anything or changed anything. It was starting and running alright, then it sat for two days and wouldn't start again. Haven't been able to start it since. 

 

No, never dealt with fusible links. 

[wayno]

The black and green wires are the fusible links, the only way to test them that is easy to explain is to unplug them from the wiring harness(white plugs) and test each wire with a volt meter or test light, they cannot be tested connected to the wiring harness.

If you know what you are doing you can feel each wire for the wire inside it, but you have to know what you are doing.

Clean the battery posts and cable connections first, I cannot count how many times I have removed the cables and when I put them back and turned the key nothing happened, or the dash lights came on and when I tried starting it the dash lights went out, I would have to get out, open the hood, twist on the cables until the heater fan came back on just to get back in and turn the key to lose everything again, or sometimes it works fine for a month and then starts that shit again, like I mentioned before, I even had the cable where it connects to the starter do that shit, after I tightened it more it started working fine again, it got to the point on one truck that it would only start using the screw driver but everything else was fine.

Edited December 12, 2019 by wayno

[SLO720]

Helped a guy out of texas with a very erratic clicking like that. His truck had a bad short in the glow plug relay iirc correctly (his truck ran but voltage surged badly). A lot of your problem sounds like a bad battery that doesnt have enough voltage to crank the engine over. If you have a way of putting a load on the battery or testing it at a parts store might be your best bet. I'll see if I can find the video or what parts I sold him to fix his issue. However, as Wayno said, no power through the fusible links and you'll have no power to anything else. I desperate enough and cant locate fusible you can set up a fuse box and run the wiring through that (not recommended but have done it for my z24 truck out of necessity). I have a three plug fusible link somewhere I believe as well with the terminal connector still attached.

 

The pictures below were what he sent me when he was researching the buzzing noise on his truck. I had a similar issue on my truck and it was the glow plug timer under the dash. The next images show how his grandfather had wired up the truck before he got it and then the last photo is of my 86 trucks new fuse box.

 

 

Edited December 12, 2019 by SLO720

[Slowas720]

I've pushed this thing around a couple times but have a bunch of other less frustrating projects I've been working on. Finally went out today and pulled both relays out from under the passenger side of the dash. Smaller relay looks fine, "timer ass'y glow after" I have no idea because it doesn't completely or easily come apart. If it is the latter, I'm screwed because these are impossible to find anywhere as I'm finding out. 

 

Edit: SOME relay under the dash on the passenger side is the only thing that makes noise when a battery is hooked up, nothing else even works but the relay will erratically and quickly make a clicking noise. 

[wayno]

I have extra glow plug timers, but first one needs to figure out if that is the issue.

Sometimes the DPC Module buzzes also, if the injection pump controller also buzzes if it is jammed, I personally have never had the glow plug timer buzz, but that doesn't mean it will not buzz, it just has never buzzed for me.

When you turn on the key does the glow plug light come on and stay on for a while?

When you turn the key on does the glow plug light just flash on for a second and go out?

Does the starter work?

Try this, unplug the wire going to the oil light sender/sensor, now while someone else turns the key on watch the injection pump arm, does it move?

 

If the starter turns the engine over I can help you get it started if it is going to run, what you do is remove the arm connected to the injection pump arm coming from the injection pump controller under the injection pump, save the washers and springs, now using a heavy gauge wire coming from the positive side of the battery touch number 4 cylinder glow plug for about a minute, this is the easiest glow plug to get to and they will all get power/warm up, you could also just jump to the white/red line wire on the glow plug relay, after warming them up for about a minute start it, floor it and turn it over till it is running.

[Slowas720]

   Alright, finally got around to tinkering with this some more. Initial cause for not running: new battery I bought was toast. Just picked up another new battery, hooked it up, and the truck will turn over for days but won't start. Thick white smoke comes out of the exhaust but it won't start. I haven't changed anything since I bought it and it started and ran fine before the battery went bad. Any ideas?

[wayno]

OK, you need to make sure the glow plugs are getting power and warming up, the white smoke likely means it is getting fuel as for it to be coolant the engine would need to be warmed up and turning the coolant to steam for it to be white.

Have a test light connected to the #4 glow plug wire/head and the other end on the negative post on the battery, then turn the ignition on and it should light up, if it does not light up and stay on for 30 seconds or more the glow plugs are not getting power/warming up and it will not likely start.

Like I said in my last post, you can warm the glow plugs up manually by using a heavy gauge wire and jumping #4 glow plug from the positive post, but either you need to see the injection pump controller arm move when your turning it over or you need to remove that arm from the injection pump as it will rest/default to the run position when not connected to the  injection pump controller, it is easier to deal with one issue at a time when dealing with this stuff via messages.

 

You need the injection pump in the run position, fuel, and warmed up glow plugs to start the engine when the engine is cold.

 

My friend had an issue with the engine not starting, I suggested the glow plugs were not warming up and he said they were, well I happened to be over there when he was trying to get it started, I mentioned the glow plus not getting power again and he looked at me like I was some newbie diesel guy, well they were not getting power and it started right up when we warmed up with a heavy gauge wire, my last post describes the way to get it started better.

[Slowas720]

 What size gauge wire would work best? I don't have any lying around so I'll need to go get a couple feet from O'Reillys, (if that ends up being the issue).

[wayno]

Something thick like the charge wire going from the alternator to the battery/starter post, at least as thick as the white/red wire going to the #4 glow plug, you don't want it getting hot while your holding it, even an old battery cable would work, or a jumper cable, but you have to be able to touch the end of #4 glow plug and nothing else.

If it is over 60 degrees outside 30 seconds might do it, but when I used to go get any diesel truck for sale that had sat for a while and was less than $500.00 I would cycle the glow plugs twice before trying to start it(1 to 2 minutes), I never failed to get one started except for one that sat in a swamp for several years, I did get it to fire on my garage floor once but it did not run.

I use any 3/16ths inch thick wire I can find, I have a couple boxes of old wire around here.

 

[Slowas720]

   Alright, thanks wayno! I'm gonna stop and grab a piece of wire today and give this a try. It's been over 80 degrees out lately so I'll hold the wire on there for about 30 seconds, two times, and then try to start her up. I did notice yesterday that the positive battery terminal was getting super hot while trying to start it so I'll grab my gloves just in case, lol.

[620slodat]

If the battery terminal was getting hot you probably have a loose/dirty connection. Take both battery terminals off and clean them real good. And for good measure, take the positive wire off the starter and clean it also.

 

Don

[Slowas720]

   So I recorded a video with my phone and it looks like the injection pump controller is moving when I turn it over. I want to make sure I'm going to the right place with this wire too: positive battery terminal to number four glow plug, which one is number four (furthest back?) and where on it should I touch the wire/jumper cable to? I imagine it'll spark a ton ...

[wayno]

When I warm up glow plugs on an engine that stuff is not working properly/is suspect I touch the END of the #4 glow plug in the first photo below, you can see the plug connected to it.

 

The second photo is of the relay, you could push the rubber boot aside on the white/red line wire and jump it from the positive side of the battery to there also, yes it could spark as your warming up 4 glow plugs, I would normally warm them up almost a full minute and then turn it over while flooring it and I would let off once it was actually running.

 

In the second photo you can see the light green wire, this is the exciter wire for activating the relay to warm the glow plugs up, if it works you could give that wire 12 volts and the relay would warm up the glow plugs, but it has to be working and you have to understand how everything works, so I took the easy route and suggested just to get it started to touch the end of #4 glow plug and then try starting it, it just seemed to be the easy way except if one doesn't have extra heavy duty wire around, and it that time I didn't have these photos either.

 

Just warm up the glow plugs and try starting it, if that does not work then remove the wire going to the oil pressure switch(yellow wire with green line) just in back of the oil filter down low on the block, when you turn the key on the injection pump controller should move to the run position if that wire is removed from the sender, if it don't move then you have other issues and will need to remove the arm from the injection pump that goes to the engine pump controller, you see when everything works properly when the oil pressure switch senses oil pressure the injection pump controller moves the injection pump to the start position, when the engine starts it moves the injection pump to the run position, and when you turn the key off it moves to the stop position, so that is why the arm has to move, it rests in the  stop position(no fuel).

 

 

[Slowas720]

Alright, so warming up the number four glow plug with a wire worked. 

 

Once I get it started it'll run and drive just fine but won't turn off with the key. 

 

So the two issues now are, why aren't the glow plugs getting heated up, and why won't it turn off. 

[wayno]

When you have it running turn the key off, then lift the hood, there is a piece of wiring harness that goes down to the injection pump controller, it has a round plug connecting it to the main wiring harness, while it is running completely unplug that plug and then plug it back in, did the engine die/shut down?

 

Does your truck have the original type of alternator?

 

Can you tell if it is charging?

 

I had a plug come loose from the alternator a long time ago and that engine would not do anything properly, it would not start because the injection pump controller would not move, but once the engine started it would move to the run position, but only after the engine started, it also would not shut off sometimes, also I had to remove the wire from the oil light sender/sensor as the injection pump controller again would not move until the engine was running, this means I was removing the control arm from the injection pump to get it started, to this day I cannot connect that oil light wire on that truck, and I have changed out the DPC Module, injection pump controller, and glow plug timer without any positive results, I have that truck on 2 oil gauges now, one electric and one mechanical.

Also the fusible links can be a major pain in the ass, if the glow plug light don't come on and stay on then you likely have a blown fusible link, the plug to the fusible links connected to the battery isn't making good contact, or the alternator might not be charging properly, why Nissan connected all this shit together to start the engine is crazy, but when it is working properly it is great, when it is not working properly it is a pain, even one wire not connected can screw everything up, if it is not charging is screws everything up, if a fusible link is bad or the plug is not making contact it screws everything up, the issue with me is I used to know all this stuff but after not having issues for a while I forget everything, but eventually I figure it out again, that plug coming out of the alternator took a while to figure out, and the oil sensor took a while to figure out also, and that damned plug going to the fusible links has always been a pain in my dually 720, as i recall the glow plug light would not stay on when that happened.