1980 Datsun 720 turbodiesel

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waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#31

Post by waynosworld » 4 years ago

I learned something new today, I have been having this issue with the injection pump controller not moving to the run position until after the engine is running, meaning it won't start unless I remove the arm, so I made a cable setup to pull on to kill the engine, and it worked great.
A couple days ago I sold a DPC module to a local guy that needed one, he said his points were fried inside it, so we put another one the truck and it started and shut down fine, I guess he knows what he is talking about.
While he was here we talked about the module and other things, while we were talking about the module he mentioned that it was wired into the oil sensor, meaning if there were no oil pressure the DPC module would not move the injection pump controller to the run position, that got me thinking, when I turn over the engine to start it, the light doesn't go out till after it starts, and the IP controller doesn't move to the run position till after it starts, so today I connected the IP controller rod/arm and pulled the oil sensor light wire, got in the truck and it started right up, and shut down like normal, then I waited a while and tried it again, and it started just fine.
I mentioned this for others to read so they don't go thru all I went thru trying to get it to work correctly, if your oil light don't go out while your turning the engine over, it will not likely start, now I don't know why it is causing this issue, as it goes out after the engine starts, at this time I don't have that wire connected, I am going to put a 720 electric oil gauge in the truck with a separate oil light next to the gauge and leave that wire unconnected, although I might buy another sensor to see if that fixes the issue, then I would only need the oil/volt gauges.
I know the voices are not real,
but they have some really good ideas.

Nissan_Ranger
Posts: 264
Joined: 13 years ago
Location: Canada

Re: 1980 Datsun 720 turbodiesel

#32

Post by Nissan_Ranger » 4 years ago

The oil filter on the SD-22 is inverted which is not something I like because if the oil filter isn't fitted with an anti-drain back valve, it will drain down over night. Not all filters have anti-drain back valves. If a filter is installed that doesn't have one, it will take several seconds of running before the light turns off after sitting all night or all day. Especially in summer...

NR
The old 'six gun' was as popular as the cell phone in its time and just as annoying when it went off in the Theater.

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#33

Post by waynosworld » 4 years ago

Nissan_Ranger wrote:The oil filter on the SD-22 is inverted which is not something I like because if the oil filter isn't fitted with an anti-drain back valve, it will drain down over night. Not all filters have anti-drain back valves. If a filter is installed that doesn't have one, it will take several seconds of running before the light turns off after sitting all night or all day. Especially in summer...

NR

I believe I am fighting several things at one time, but disconnecting that oil sensor took that out of it, I am also fighting a fatigued wiring issue between the injection pump controller and where it goes into the engine bay harness, if it doesn't move when I turn the key on, I have to wiggle that part of the harness and it does start working again, it's hard to diagnose issues when I have more than one issue causing the same issue, it's got a lot easier since I removed that oil sensor wire, and I did put another oil sensor in it today, but it is still disconnected.
If the DPC is truly wired into the oil pressure, then that sensor has to be sensitive because I am used to my diesels starting up right away without hesitation, and that would mean it would have to show some kind of pressure after even half a turn, but since I disconnected the oil sensor wire, it moves right when I turn on the key, if it doesn't I need to wiggle the wiring harness and then it moves right away.
I have never had a diesel like this one that stuff breaks right after I fix another broken thing, but it has been sitting for a year because it was running so hot(EGTs), so now I don't have to worry about that, the clutch slave gave up today, I am going to tow the MGTD to the upholstery guy tomorrow morning with this truck to have side curtains made, I hope everything holds up.
I know the voices are not real,
but they have some really good ideas.

Nissan_Ranger
Posts: 264
Joined: 13 years ago
Location: Canada

Re: 1980 Datsun 720 turbodiesel

#34

Post by Nissan_Ranger » 4 years ago

Yeah, I know that feeling of fighting problems on multiple fronts! I got rid of the entire wiring harness and put in a manual cable when I transplanted my SD22 into my Ranger.
The old 'six gun' was as popular as the cell phone in its time and just as annoying when it went off in the Theater.

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#35

Post by waynosworld » 4 years ago

The tow went off without a problem, although the EGTs climbed to a little over 1200 degrees.
Although this is a cheat dually with adapters holding the dually wheels on that is more for show than actual use, it tows great because it is a dually, I would not actually try to haul a lot of weight.
The true dually rear axle does not have the gearing needed for a SD series diesel(3.9 minimum), at best you can buy 4.11 gearing for the dually axle, I have 3.3 gears in a regular rear axle with adapters to mount dually rims.
The Datsun 521 work truck is far better suited to tow with, it has 4.37 gears in a dually axle, and a way more powerful engine, but it doesn't get the mileage that the diesel gets, and the tow wiring is different, so it is easier for me to tow with the 720 locally.
Here is the work truck hauling two tons of chemicals, one ton on the flatbed, one ton in the trailer.
Image
Image
Here is the car I towed today.
Image
Image
I know the voices are not real,
but they have some really good ideas.

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#36

Post by waynosworld » 4 years ago

Well it has been a while, I have been driving it as much as possible, took it out today on a Datsun Cruise, I determined that I had the wrong vehicle as everyone else had cars, and then there was me in my dually diesel truck trying to keep up on winding Mountain roads, one of the guys behind me said I had one rear dually side wheel airborne and spinning, I don't believe it is true, as I didn't feel it break lose, but the front tires were squealing and my front brakes almost caught fire.
Anyway my throttle cable dropped out of position and rested on the exhaust manifold head pipe and all of a sudden I had throttle issues, it would not drop to idle anymore, well after we got to the top of the hill the guys stopped and had to repair another guys throttle return spring, so mine cooled off enough to act normally again, but I started having issues again on my way home, that is when I figured out my issue, after I got home.
So I got it moving slightly better and went to the auto parts store and ordered a new one(supposed to be here Monday), so I went home and then made a modification to my engine, I put a hose from my vacuum throttle control line to my boost gauge line with a boost controller valve in the middle, I believe that the boost will help push the rack to a richer position when I have boost, but when I let off the pedal I will have vacuum, this will help pull the rack to the idle postion, my thinking is that I cannot seem to get enough fuel, especially on the hiway, so after talking to the guy that did the turbo bomb thread, I decided to try this mod, I entered the hiway and opened up the boost control knob and I could feel it, that dead spot at 2500rpms was gone and I kept gaining speed, I noticed at about the same time that I hit 18psi that something came apart, I let off and slowed down some, as that was the fastest I had ever went in this truck, I was of the opinion that I lost a transmission bearing, I tried 4th gear but it didn't seem to change, so I made a quick decision to get off the freeway now and limp home, I tried all the gears and the sound continued till I got home.
Once home I popped the hood while it was running to see if I could figure out what the noise was, my idle was also a little high but I thought it was a throttle cable issue, well it didn't take long, my home made vacuum release valve made of PVC had blown apart, I figure that it was just to hot in the engine compartment for the PVC material, and 18psi was just to much for it to hold together, where the cotter pin was had just pulled thru the hot PVC material till it let loose, I will take a photo of the part later, I just drilled another hole 90 degrees off and put it back together.
I am happy to say that the modification worked, I had way more power on that last test drive, it quickly went up to 70mph+ just before blowing the valve apart, but I didn't have enough time to get a lot of input, I was looking at the gauges, boost controller adjustment, and the road ahead of me along with all the traffic, I have no idea if it was blowing black smoke, nor did I have enough time to see what the EGTs were going to do, I believe I will need a 20 mile trip on the hiway to get a good idea of what is going on.
I also need to make a metal valve, as the PVC is not going to hold up, but first I need a good throttle cable that doesn't stick.
I learned a lot today, one was that if I go on another Datsun cruise, take the Roadster!!!
I know the voices are not real,
but they have some really good ideas.

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#37

Post by waynosworld » 4 years ago

Well this is what I came up with, I made another one with a aluminum tube, and when I drilled it I drilled it in a place with more meat.
Here is why it blew apart.
Image
The other side.
Image
And here it is installed.
Image
Fact is on that winding road I was driving on yesterday the engine got mighty warm, the EGTs were over 1200 degrees, that likely didn't help, it likely had been coming apart the whole day, and that 18psi was the straw that broke the camels back.
I am hoping this one will last longer till I find something that will work that is all metal.
I know the voices are not real,
but they have some really good ideas.

plenzen
Posts: 868
Joined: 13 years ago
Location: Cochrane Alberta Canada

Re: 1980 Datsun 720 turbodiesel

#38

Post by plenzen » 4 years ago

The black ABS piping is a bit more robust than the pvc is. (thicker wall)

I have had some 4 inch as a CAI for years and no problem.
It's also rated to 100 psi I believe and temp rated to 140 f ( I think )

Just a thought.
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#39

Post by waynosworld » 4 years ago

plenzen wrote:The black ABS piping is a bit more robust than the pvc is. (thicker wall)

I have had some 4 inch as a CAI for years and no problem.
It's also rated to 100 psi I believe and temp rated to 140 f ( I think )

Just a thought.
I thought I had the boost set for just under 15psi, but the better I make this setup the higher the boost is going without touching anything boost related, at first I was lucky to get to 10psi, now I think I will have to do some adjusting, I believe that I will hit 20psi if I am not careful, it is an old engine, at least that is what Larry kept saying to me.
I will look into ABS, but these PVC fittings fit the aluminum tubing perfect, I doubt the ABS will be the same size.
I need to find something all metal that will work, I actually thought that the ping pong ball was going to be the weak spot.
I know the voices are not real,
but they have some really good ideas.

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#40

Post by waynosworld » 4 years ago

OK, the engine has good oil pressure, this is at a 750rpm idle.
Image
I had to use a sandwich adapter plate to mount the oil gauge sensor, it was under $10.00 shipped to my door.
Image
Image
I am kinda playing with the fuel mixture now with a boost controller, I figured out how to give it more fuel using the boost to help it, and when I let off the pedal the boost goes away, and so does the fuel, no boost, no fuel.
I still have the vacuum issue though, and I just shortened the spring to much and it didn't help, it just don't idle as good, so I stretched the spring a little and now it idles good again, you see if I have a high idle, I have less vacuum when I let off the pedal, if I have a low idle, I have more vacuum when I let off the pedal, when I talk about letting off the pedal I mean that I am cruising down the road in second gear at about 2000rpms and let off the pedal completely I get 5psi of vacuum, if I almost let off the pedal all the way I only have 2psi, it's hard/strange to not let off all the way, but I am learning how to drive it, I don't know what it does in fifth on the hiway right now as I just got it tuned in today, and I have not had it on the hiway today, I will find out tomorrow when I go down town to pay my property taxes and get tags for 2 of the trucks.
Vacuum pulls oil thru the seal of the turbo, the more vacuum the more oil gets pulled thru, I know this because the inside of the intake is coated with oil.
The vacuum valve was coming apart again, the holes were elongated again, so I drilled 4 more holes in the tube and put 4 screws into the PVC, it is just to hot in the engine compartment for PVC, I am going to have to come up with something made out of just metal.
I know the voices are not real,
but they have some really good ideas.

Nissan_Ranger
Posts: 264
Joined: 13 years ago
Location: Canada

Re: 1980 Datsun 720 turbodiesel

#41

Post by Nissan_Ranger » 4 years ago

Looking good, Wayne!
The old 'six gun' was as popular as the cell phone in its time and just as annoying when it went off in the Theater.

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#42

Post by waynosworld » 4 years ago

I am a little worried about the kind of oil pressure I have, never had an engine with this kind of pressure, but maybe it has something to do with where the sender is located now, but the gauge pegged bothers me, especially at an idle.
Image
And this is at a 632rpm idle.
Image
After it warmed up it was at about 40psi at an adle, but once I start driving it gets up to 80psi plus again, is this normal?

I also have been thinking about my vacuum issue, it went up to 5psi vacuum(-5psi) from 2/3psi after I added that boost line to the injection pump control vacuum line, I am beginning to think it is a false vacuum reading of sorts, you see when I connected the boost line to the gauge to that line I also connected the gauge to the venturi that controls the rack also, so I am wondering if there is more vacuum in that line than there is in the actual intake system itself when I let off the pedal, but I don't want to change to much as it runs great right now.
I suppose I could connect the boost gauge line to the line between the compressor and the waste gate control to isolate the gauge from the injection pump control line to see if that changes the way the gauge reads, at one point I had a separate boost gauge connected there and they both showed the same pressure, but that was before I had it piped the way it is now.
I hope you guys understand what I am talking about, as if someone else has already done all this and could tell me what I might be missing or doing wrong, or maybe I am blazing a new trail here, eventually I will get this figured out.
I know the voices are not real,
but they have some really good ideas.

handcannon
Posts: 57
Joined: 4 years ago

Re: 1980 Datsun 720 turbodiesel

#43

Post by handcannon » 4 years ago

I just read through this whole thread, but I need to go back and read it all again in order to properly understand what has been done. One of my first questions is what kind of fuel mileage are you getting now?

I need to back up a bit and explain what I have. I have my Dad's 1973 Datsun 620 pickup. About 10 years ago I parked it after something happened to the original motor. It acted like it jumped time, and I never did anything to try and diagnose it, just parked it. After getting a Chevy diesel pickup I started looking for some kind of diesel motor for the Datsun.

Somewhere close to a couple years ago I found an SD-22 and 5 speed transmission from a 720 pickup, planning to put it into Dad's pickup. I think it was out of a 1981 pickup. I've had the motor running while setting on the shop floor. I know it has decent oil pressure as I put a mechanical gauge on it. I recently surfaced the flywheel and new got clutch parts for it. Now I just need to find the time to start the swap.

My primary interest is in fuel mileage. But, I might also try to turbo it. From what I've found out about the SD-22 it has problems that need to be worked out to successfully add a turbo, which is why this thread has been so interesting for me. I do have some ideas I want to try eventually, but I first need to get it into the 620, and running good. Everything you are doing here is definitely of interest to me.

Don

plenzen
Posts: 868
Joined: 13 years ago
Location: Cochrane Alberta Canada

Re: 1980 Datsun 720 turbodiesel

#44

Post by plenzen » 4 years ago

Welcome Don.

There is someone on here that did a 620/SD swap as well.

Keep up posted as to your progress
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN

waynosworld
Posts: 517
Joined: 7 years ago
Location: Vancouver Washington USA

Re: 1980 Datsun 720 turbodiesel

#45

Post by waynosworld » 4 years ago

Putting a SD22 engine in a Datsun 620 should not be that big of a deal, as there is plenty of room in the engine compartment, I actually bought a SD25 that came out of a 620 and put it in my 1969 Datsun 521 kingcab, it was tight, but I succeeded, here is a link to that thread, it is not turbocharged, but yesterday I drove it for a while, it just doesn't have the power of the turbocharged 720, but it doesn't have any of the issues either.
https://www.google.com/url?sa=t&rct=j&q ... 4746,d.cGc
I have had several 720s with SD22 diesel engines in them, I averaged 25mpg in the city, and as good as 36mpg on the hiway going 50/55mph, but I normally get about 28/29mpg on the hiway because I drive 70/75mph all the time on the hiway, I cannot drive 55mph.
Another thing to keep in mind is that all my engines right now are SD25 engines, they all came with turbo pistons as far as I know, so I am not sure about turbocharging SD22 engines, they do not have turbo pistons, but maybe the SD33 turbo pistons can be used.
This thread is my adventure in trying to solve all the issues with installing a turbocharger onto a SD series engine with an inline injection pump, so far it has worked out for the most part except for the vacuum issue when I let off the pedal, at first I was seeing 10psi vacuum, I have it down to 5psi or less depending on the circumstances, but every time I pull the intake system apart to make changes, I find oil covering everything inside it, a few weeks ago I integrated the inner-cooler back into the system, now I am afraid that it will eventually fill up with oil as it is the lowest thing in the system, I am going to put a drain in it, but that is not what I was shooting for.
Another guy on here says he figured out how to turbocharge this engine with the throttle body in the stock location, I tried it that way for a while but could not deal with the high EGTs(exhaust gas temps), but he says that he did it with the injection pump vacuum lines, I figured out how to get my engine running good messing around with the vacuum lines also, but in the end I still have this vacuum issue that pulls oil thru the turbo seal into the intake system even with the valve I made, it just doesn't pull the oil thru the seal near as fast, but it runs good, and I have lots of boost to play with.
So far the best fuel mileage I have gotten with this setup is 23/24mpg, but I have not had it on a hiway more than 5 miles, it mostly has been on my neighborhood streets and idling in the driveway, I am not yet ready to take it on a trip as every time I push it something happens that makes me happy that I am close to home, so far I have always been able to repair it on the side of the road and get home without an issue.
Where are you located Don?
handcannon wrote:I just read through this whole thread, but I need to go back and read it all again in order to properly understand what has been done. One of my first questions is what kind of fuel mileage are you getting now?

I need to back up a bit and explain what I have. I have my Dad's 1973 Datsun 620 pickup. About 10 years ago I parked it after something happened to the original motor. It acted like it jumped time, and I never did anything to try and diagnose it, just parked it. After getting a Chevy diesel pickup I started looking for some kind of diesel motor for the Datsun.

Somewhere close to a couple years ago I found an SD-22 and 5 speed transmission from a 720 pickup, planning to put it into Dad's pickup. I think it was out of a 1981 pickup. I've had the motor running while setting on the shop floor. I know it has decent oil pressure as I put a mechanical gauge on it. I recently surfaced the flywheel and new got clutch parts for it. Now I just need to find the time to start the swap.

My primary interest is in fuel mileage. But, I might also try to turbo it. From what I've found out about the SD-22 it has problems that need to be worked out to successfully add a turbo, which is why this thread has been so interesting for me. I do have some ideas I want to try eventually, but I first need to get it into the 620, and running good. Everything you are doing here is definitely of interest to me.

Don
I know the voices are not real,
but they have some really good ideas.

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