1983 Datsun 720 SD22

[Bakonbitz]

Just got my grandpas old 1983 Datsun 720 with a SD22 in it. It was parked for 25 years in the back field but with a little bit of maintenance she’s up and running. Just have a few little quirks to work out if anyone could give me some insight. 
 

Tail lights, everything works, brake lights, reverse, and signals. But the tail lights don’t come on when I turn the headlights on for night driving. 
 

I’ve heard of many people here getting good fuel economy with this engine, however I’m using over half a tank to drive 150/km. Wondering if anyone has any ideas as to the reason for this. 
 

also wondering what would be some good options of diesel engines to swap out that could be turbo’d. was thinking of a TDI ALH but not sure if it’s possible. 

[datzenmike]

Many things on this truck says it can't be an '83.

 

Has '81-'82 hood and the square gauge cluster as well as the horizontal tail lights. The '83 model year started in December '82, had an SD25 engine, round gauges, tail lights mounted vertically in the box corners and the hood did not have those louvers and the fender emblems simply say NISSAN. I think there is a build date on a tag on the driver's door jam.

 

The following is much easier if you go to Crappy Tire and get a $5 test lamp. Ground one end and if the probe end touches anything with 12v it lights up. You don't need a meter and if you don't have one of these you really do need one.

 

Do the front parking lights and dash lights come on with the headlights? If yes this is good and shows the switch and the fuse are ok. The brake and turn signals shows it isn't a ground problem. Have a look behind the right rear tail light at or near the end of the frame rail. This is where the external body harness ends at a round six wire plug into the tail light harness that runs across the back. The tail lights/side marker and license light wire id Red/Yellow. Before testing for power try unplugging and plugging it back in a couple of times. (it's exposed to damage from flying rocks and salt water) This will clean the contact surfaces. If still no lights test for power.

 

If power, but no lights then the E  Red/Yellow wire is damaged on the tail light harness.

If no power, slide the passenger seat back and on the floor in front is a 10 pin connector.

 

This is the other end of the body harness coming up through the floor and where it joins the dash harness. Unplug and test the Red/Yellow wire for power. Very likely it will have power and the fault is a broken wire under the truck where it's exposed to rock hits and damage.    

 

Fuel mileage... wayno ( https://ratsun.net/profile/5657-wayno/) is our resident SD 22/25 expert. He'll know more about this and probably how to adjust the engine. He has also done a turbo on them.

[NC85ST]

On 9/3/2023 at 3:31 PM, Bakonbitz said:

good options of diesel engines to swap out

Maybe this is an option. It’s on for sale on Facebook.

34mpg, 4x4, Kubota v2203-di diesel engine, turbocharged, Nissan 350z 6 speed manual transmission, electric overdrive unit, new all-terrain tires, powder-coated frame, Bluetooth radio, new starter, new battery, built by a 70 year old farmer from Virginia back in 2007.

 

 

[datzenmike]

'85 or '86

[NC85ST]

The ad says it’s an ‘85. It’s located in Jefferson, NC.

[Bakonbitz]

On 9/3/2023 at 6:35 PM, datzenmike said:

Many things on this truck says it can't be an '83.

 

Has '81-'82 hood and the square gauge cluster as well as the horizontal tail lights. The '83 model year started in December '82, had an SD25 engine, round gauges, tail lights mounted vertically in the box corners and the hood did not have those louvers and the fender emblems simply say NISSAN. I think there is a build date on a tag on the driver's door jam.

 

The following is much easier if you go to Crappy Tire and get a $5 test lamp. Ground one end and if the probe end touches anything with 12v it lights up. You don't need a meter and if you don't have one of these you really do need one.

 

Do the front parking lights and dash lights come on with the headlights? If yes this is good and shows the switch and the fuse are ok. The brake and turn signals shows it isn't a ground problem. Have a look behind the right rear tail light at or near the end of the frame rail. This is where the external body harness ends at a round six wire plug into the tail light harness that runs across the back. The tail lights/side marker and license light wire id Red/Yellow. Before testing for power try unplugging and plugging it back in a couple of times. (it's exposed to damage from flying rocks and salt water) This will clean the contact surfaces. If still no lights test for power.

 

If power, but no lights then the E  Red/Yellow wire is damaged on the tail light harness.

If no power, slide the passenger seat back and on the floor in front is a 10 pin connector.

 

This is the other end of the body harness coming up through the floor and where it joins the dash harness. Unplug and test the Red/Yellow wire for power. Very likely it will have power and the fault is a broken wire under the truck where it's exposed to rock hits and damage.    

 

Fuel mileage... wayno ( https://ratsun.net/profile/5657-wayno/) is our resident SD 22/25 expert. He'll know more about this and probably how to adjust the engine. He has also done a turbo on them.

You are correct, apparently I fat fingered it twice. It is an 82 with the sd22 in it. Figured out the problem with the tail lights, the bulbs aren’t making proper contact in the socket unless I rotate them a specific way. Appreciate the in depth response to the wiring!