1980 Datsun 720 turbodiesel

[waynosworld]

OK, I have a question about the DPC Module, it appears to be tied into everything, I know it is connected to the oil sender/sensor and the engine will not start unless there is oil pressure, well it appears to be connected to the alternator also and if the alternator is not charging it will not start either, I figured this out today because my alternator was not charging, I disconnected the IP control arm as I needed the engine to start, I played around with the alternator wiring, and the fusible link wiring, IP controller plug was cycled also, and I also tried another DPC Module but there was no difference, it would not charge, I had gave up and connected the old DPC Module and started looking for new power steering leaks again as I have an issue there and there was a loud pop like when the glow plugs finish warming up and that is when the alternator normally starts charging when it has been working/charging in the past, I got curious because this pop happened even after the engine had been running for several minutes, it may have been a minute after I had finished plugging in the old DPC Module, anyway I walked around the truck and looked at the volt gauge and it was charging for the first time in a quite a while as the IP controller arm has been removed for quite a while also, so I must have done something that changed something, does anyone on here have an idea?
Also my oil sensor line has been disconnected for a few years now as I have the same issue when it is connected, it will not start when it is connected, any ideas as I have changed out the sensor/sender a couple times without positive results, any ideas why this is an issue?
I did hear the DPC Module buzzing when I connected the battery back up after changing out the turbocharger system, it buzzed a few times after connecting it even though the ignition was not on, changing it out to another one made no difference though.
I forgot to mention that after it started charging I connected the IP control arm back up to the IP and it works normally again, it starts and shuts down with the key.
If anyone on here knows about this stuff could you help me understand it, the reason I have the oil gauge is because the engine will not start with the oil light wire connected unless I disconnect that wire from the sender/sensor, and I actually have 2 oil pressure gauges, the stock 720 electric type that shows low pressure all the time, and the mechanical one that shows lots of pressure(over 60psi when driving), that is likely a wire issue also.
Anyone on here know about this stuff?

[waynosworld]

So I have been messing with the turbochargers over the last month or so,
the last turbo I installed was too high and made a lot of noise, so I
bought a turbocharger on ebay like the one that was on it when I bought
the Volvo with the SD25 engine, but this one is not modified(larger
compressor vane), I got that one going and it is way quieter, I also
made a lower mount, it is better and will still make a lot of PSI when I
am going thru the gears but when I let off at 65mph and cruise at an
even speed it only makes around 8psi, it runs warmer(EGTs) than the 521
kingcab engine, but this injection pump is modified also to run richer.

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[waynosworld]

So I decided to try something new, I made my own turbo exhaust manifold, it's been called a log manifold on another forum, my welding is not pretty, but it will hold and likely will not leak, I am thinking about making another one a different way and I am sure it will be nicer.

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I do not know if this was a good place for the bung for the EGT probe, but the metal tube holding the turbo is a much thinner metal and I did't want to drill a hole in it or weld a thick piece of metal onto that thinner metal and maybe melt thru.

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[waynosworld]

OK, I had to modify the waste gate mount bracket in post 62 to have the compressor discharge pointed the direction I wanted, well yesterday I decided to reconnect the inter-cooler back up, it turns out if I had just done that in the first place I would not have had to modify anything.
I took it for a test drive and it has never run better since owning it, it is also quieter for some reason, it still is at 8psi cruising at 65/70mph and jumps up to almost 15psi when going thru the gears or putting my foot into it on the freeway.
The EGTs are the same even though it has the inter-cooler connected, I have never noticed much of a difference but my inter-cooler is not hanging out in the open either, it's behind the grill and bumper, but so is the radiator and it cools the engine even with the inter-cooler and piping in front of it, if I had it to do again I would not have cut my sheet metal to install it as it is less than a 100 degrees difference between cooler and no cooler.
Here is the engine compartment with the inter-cooler piped in, not a lot of room to work on things on that side anymore.

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Here is the truck as it sits today, I put some Nissan 4wd leafs in the rear to lower it a little.

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My Datsun 521 kingcab turbodiesel is still a better/funner truck to drive, it has an OEM 1985/86 Subaru XT turbocharger on it, on the freeway cruising at 75mph it creates 4/6psi and runs cooler, but the EGT probe is just after the turbo instead of before it, so till I get around to relocating the probe I will not know how hot the EGTs are for sure, but the freeway cruising PSI(boost) is what I am happiest about, it has plenty of power with 4/6psi boost, it still gets up to 12/13psi when I am getting on it, the waste gate is adjusted to go no higher.

[waynosworld]

Well it has been years since I drove this truck, it sat for about 6 years, last registered in 2020, time has taken a toll on this truck, but I have revived it from the parking spot it has had for so long, I always started it and warmed it up a couple times a year, but never drove it on the street, I had to do the rear brakes, and fix an issue of one shoe moving out of position, I had to change out the clutch master and slave, I had to blead the brakes, I went back to my normal dually wheels, all the glass had to be cleaned so I could see out of the truck, then the power steering hose sprung a leak, I had an extra line/hose, I re-did the piping between the turbo and intake, much nicer now, I broke the hood release, I jury rigged in something until I can find another one or have one made, and I had a new exhaust system out in it, I drive it most days now, most the little stuff that gave me issues have been fixed, it is actually quiet inside the cab when driving it.

t sat so long the fuel tank got holes in it near the halfway up seam where to top and bottom are welded together, it appears so far that JB Weld fixed that

I need to take photos.

It appears to be dependable, I am driving it today and have been for close to a month now, revived from the almost dead.

[plenzen]

IT LIVES !!!! Risen from ????.............. well............ near death. Sadly the engine will outlive the body,frame,etc.

IIRC your near 70 yrs. How's that crawling around on the ground and kneeling down beside it working out for you ?
For me (73) getting on the ground is the easy part. ( gravity you heartless bitch !) ( wish I had a lift )
Still managing to crawl under the 2 vehicles we have to do oil changes and even do winter tire swaps ( got one of them wheel lift thingys, works good)
But other than that not too much more. Under dash work is a distant memory.

There are times I really miss my old Nissan, however watching it sit there most days rusting away was not what I wanted.
It lives and is driven still ( I think) in Southern Manitoba near the North Dakota border.

Good to see you revived the old girl.
Pics would be good to compare to the ones posted above your post 7 yrs ago.

Paul

[waynosworld]

LOL, that extra power steering line sprung a leak also, I temporarily fixed it with a bike rim tube and a lot of hose clamps, I did 3 spots, I was hoping the hose clamps tight enough would stop the fluid from migrating from one patched spot to the next, but the leak just moved to the next spot the outer covering had a hole, it appears I am going to have to have a new line made, not sure if that is easily done anymore, I have another idea but I will talk about that idea if it works.

I am driving the 521 kingcab turbodiesel today, I like it better anyway, but I only drove the 1980 Datsun for less than two years before making the 521 my daily driver, the 1980 is an alright truck, but the 521 is awesome.

[plenzen]

I would think there has to be a place there that makes hydraulic hoses.

Just a quick google search provided this:

Vancouver, Washington features specialized providers for hydraulic hose repair and industrial equipment needs.
• Hydraulics, Inc.: Provides downtown-adjacent shop service, custom Eaton Aeroquip assemblies made in minutes, pump/cylinder repairs, and crane or DOT vehicle inspections.
• Advanced Hydraulic Supply Vancouver: Operates as an industrial equipment supplier focused on specialized component sourcing and hardware provisioning.
• ARG Industrial, HOSE PRO Service: Delivers on-site mobile hose fabrication and maintenance with crimping capabilities up to 2 inches and extensive fitting inventories.


You'll get it figured I'm sure

[waynosworld]

I would think there has to be a place there that makes hydraulic hoses.

Just a quick google search provided this:

Vancouver, Washington features specialized providers for hydraulic hose repair and industrial equipment needs.
• Hydraulics, Inc.: Provides downtown-adjacent shop service, custom Eaton Aeroquip assemblies made in minutes, pump/cylinder repairs, and crane or DOT vehicle inspections.
• Advanced Hydraulic Supply Vancouver: Operates as an industrial equipment supplier focused on specialized component sourcing and hardware provisioning.
• ARG Industrial, HOSE PRO Service: Delivers on-site mobile hose fabrication and maintenance with crimping capabilities up to 2 inches and extensive fitting inventories.


You'll get it figured I'm sure

I went to "hydraulics Inc" this morning, they said they will put a new hose on my power steering line, I wish there was a way to just change the hose using threads, but I suspect it does not fail enough to make a part like that, still it was expensive, 10+ years ago I would have figured something else out, like converting over to the hardbody(D21) system like my 521 kingcab turbodiesel has, I did not have the room for the 720 Z24 pump with the reservoir, I had to have remote reservoir put in the only spot I had room for it up by the firewall next to the spin on fuel filter, the power steering pump is much smaller without the reservoir, but the diesel power steering setup is very compact but covers the injection pump controller, I would have to pull apart most everything on that side just to get in that area. I need more room or needed a better plan, but that was back in 2008/09 when I built that truck.

Fact is I forgot I had that diesel power steering setup in a container, this truck has the room, I am getting forgetful.