The SD23 thread

[elminero67]

Thought I'd start a new thread specific to the SD23 motor.
I suspect these will start to become more common in the United States and Canada as 'low milage" SD23s are available through JDM imports at a price that is comparable to rebuilding a SD22.

I paid $1300 for mine a few weeks back, and figured I could swap most of the parts from my tired SD22. For the most part this is true.

What I did find was there just isn't a lot of reliable information on SD23s online. The places the SD23s were sold are mostly in third world countries with limited internet or do not speak English, so whatever information our fellow Nissan gearheads in Asia that are familiar with the SD23 have-is lost in a cultural/language gap.

This thread will look into the SD23. As I find information, I'll post it, but I hope others jump in and make it a good resource for others looking for answers.

Some of the questions I have on the top of my head are:

What years was the SD23 made? What models?

Why do we have a SD23 when the SD25 was available simultaneously?

Why does the SD23 have a higher HP rating (73hp) than the larger SD25?

Here are a couple pics I gleaned from the Philippines:
The first is a 1991 Nissan "Bida" with a SD23.
The second is a SD23 in a 1998 Bida. Note the inline IP:

[elminero67]

Here's one theory on the SD23 and why it is rated for more HP than SD25. Could it have a slightly higher compression than the SD25, as Nissan left the displacement smaller so the head would be stronger. This is just a theory based on no information...

I do know that in many 3rd world countries the diesel is "better" than the low-sulfur diesel available in the US, I know that when I took my SD22 to Mexico it ran noticeably better!

1990 dual cab with an SD23:

[elminero67]

Check out this 1986 Sd23 "Datsun" hardbody. 4x4 and crewcab! The post looked like it was written in Russian.

[elminero67]

Here are a couple of vehicles equipped with SD23s that you wouldn't expect:

Here is a medium duty, 1985 Nissan Atlas. Wonder what transmission this would have?



Or a 1999 Kia Besta, sold in south American markets with a SD23

[waynosworld]

This is the manual I am getting the info below out of.
NISSAN MODEL SD SERIES DIESEL ENGINE SD22, SD23, SD25, SD33
SERVICE MANUAL Publication No. SM3E-00SDG0

According to the manual, the SD22 has a 20.8 CR, the SD23 has a 20.5 CR, the SD25 has a 20.7 CR except for the 720 model which has 21.4 CR.

According to the manual the SD23 only came with the VE type injection pump on the E23 and 720 models, and only in Europe and Australia in the 720 models, don't know about the E23 model, but there are no remarks as to where that was exported.

According to the manual, all SD23/25 engines came with 5 main bearings and 3 rings.
The SD22 was a mix, some had 3 main bearings, some had 5 main bearings, some had 3 rings, some had 5 rings.

Now industrial/marine engines are another can of worms, and I don't have a manual for that.

[plenzen]

Interesting.
I wonder if the 23 is not a hybrid ( for lack of a better term ) between the 22 and the 25.
What i mean is perhaps Nissan had a bunch of 5 main cranks left from the end of the 22/ 5 main production and used the 25 liners and pistons or the other way, and maybe they started making the 25 cranks and used up a bunch of 22 pistons and liners.,,,,,,,,,,,,,,,,,,, maybe. (shrug)

Would be interesting to see if you can calculate 2300 cc's by using bore and stroke from pieces of both.
Just a thought.
I dont think the 23 was built for that long was it ?

As for the industrial/marine 22 engines ( like the one rustie got from sootfart) that engine will have 5 rings and a steel insert in the top ring groove as well. I don't believe the auto versions had the steel insert. ( not to say you could not buy it aftermarket but not OE I don't think )
But, I been wrong before. I seen it happen

[elminero67]

Well there goes my compression theory!

If the Sd23 is the factory motor for the South American Kia Bestas as I suspect, they were made as late as 1999. it is possible that these were aftermarket motor swaps-but a quick Google search shows a lot of 1992-1999 Kia Bestas for sale with SD23 motors.

I have seen several SD23s with the inline IP. Not proof that they were offered from the factory as they obviously can be swapped.

One thing I did not see during last nights two-hour marathon surf of every posting on SD23s was evidence of a factory turbo on the SD23 as rumored.

Maybe Nissan let others manufacture this motor in the Philippines and/or South America? I know the Nissan Patrol was built in India (called the Jonga) and the Philippines.

Still working on this. The point is I suspect that these motors are more common and have more potential variations and transmission options than we see in the US, Canada and Australia. we just need to think outside the box. As parts are drying up for Sd22's and SD25's, finding alternative sources for parts may buy these stinky, smoky, antiquated ol' motors some time.

[waynosworld]

The manual I quoted was dated 1983, anything made after that will likely need a different manual, it could be different.

[plenzen]

I thought that I heard someplace that they were still making the SD for forklift applications until recently.

Maybe have to go onto Nissan's industrial side to see what's there.
As you stated we have to think outside the box perhaps.
They may not make them for the automotive applications but for industrial applications they might.

EG: Chrysler Marine made 273's 318's and 383's long after they were no longer available for automotive use.

[ehtrain]

One thing I did not see during last nights two-hour marathon surf of every posting on SD23s was evidence of a factory turbo on the SD23 as rumored.

Still working on this. The point is I suspect that these motors are more common and have more potential variations and transmission options than we see in the US, Canada and Australia. we just need to think outside the box. As parts are drying up for Sd22's and SD25's, finding alternative sources for parts may buy these stinky, smoky, antiquated ol' motors some time.

I also extensively searched for an sd23 turbo manifold as it should be the same as the sd25. my answer led me to only marine applications but finding one... well I put word in with some jap parts exporters and they came up empty handed.

also if im not mistaken the only difference between the sd23 and sd25 is the stroke.
I don't want you to see the shameful roodogs parts but ill show you.


look very closely on the label and it says sd23/sd25 piston NEW


look closely you will see sd22/sd25 on main bearings box, sd22/23/25 on the rod bearings box, and sd22/sd25 on cam bearings


the gasket set lists sd23/sd25


rings of course say sd23/sd25, the crank thrust bearings apparently do sd20,22,23,25,33 and more? wow, Id be willing to take a guess it probably uses the same valve springs also as the valve guid box lists sd23/sd25

[plenzen]

Where did you order the parts from ?

[ehtrain]

those are roodogs 4wd spares or what ever he is called, google it up bro. the same parts that cost me 3 rebuilds.... trust me dont buy his junk, but thats my experience. nissan makes all the parts for these motors still pretty much and they are flawless quality. for reference sake the sd25 is 89x100mm stroke. not sure what the sd23 is

you might have to find main bearings as it would appear but otherwise look on http://nissandiesel.dyndns.org/viewtopic.php?t=3323

worst case sd25 cam, sd25 head, id hope everything else would be the same but the crank. otherwise you can still order the injection pump and gears etc for the sd25 right from oem.

i also found out that the ka24e uses the same rear main seal and pilot bushing as my sd25. it may also be the same for the sd23? the sd25 and ka24e have a rear plate that bolts to block and oil pan that houses the rear seal. I want to try putting a ka24e flywheel on also and see if ring gear and mounting etc works out

[ehtrain]

after putting bunch of numbers into sd25 FAQ i found out the sd23 listsa 46mm throw and 174.2mm rod

while the sd22,sd25,sd33 have 50mm throw and 170mm rod length

the info also does NOT list a 5 ring piston for the sd23 in ring and piston checks. Whether that is true I dunno

so it would seem the sd23 is the weird duck in the bunch

[spajetti]

I'm surprised to see that there is a forum like this for an otherwise unnoticed truck in our country (Philippines). I have a beat-up but reliable Nissan pick-up powered by an sd23 motor. Here, it's pretty much more of a 'service' or 'delivery' vehicle than a day-to-day truck. Also, we have tons of parts for these; original factory issue and replacement.