Is the SD22 Alternator the same as an SD 23 alternator?

SD diesels were widely available in the US in the 1981-86 Datsun/Nissan 720 pickups, and in Canada through '87 in the D21 pickup.

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Josefbloe
Posts: 4
Joined: 7 years ago
Location: Northern NSW Australia

Is the SD22 Alternator the same as an SD 23 alternator?

#1

Post by Josefbloe »

I have a 1986 E23 series Nissan Urvan SD23 Diesel Microbus and the alternator is Cactus (A cheap Chinese Replacement with a broken shaft) with no numbers on it. I have searched the internet for a replacement but all alternators shown in diagrams seem to be different to what I have. My service manual only covers the SD22 engine but it does give a number for the SD22 alternator which is LT140-107 so is the SD23 engine alternator the same beast? I spoke to a Nissan Dealer and he gave me the Nissan part number for the SD23 engine alternator which is 23100R8800 but obviously the two sets of numbers are different, maybe because one is from Nissan and the other is from Hitachi (the makers of the original Alternator) but I'm only guessing. I can buy an alternator apparently but the auto shop has to get it in so I want to make sure it's the right one so can anybody help me?
I'm from Australia so all replies have to be written upside down!
plenzen
Posts: 869
Joined: 14 years ago
Location: Cochrane Alberta Canada

#2

Post by plenzen »

If it will bolt on then it really doesn't matter what alternator you put on it as long as it can be wired in to do what its supposed to do, charge a battery and keep your accessories running.
Must also carry the proper amperage to supply whats required as well.
Check for SD25 as well.

I assume that the shaft your speaking of is for the vacuum pump at the rear or ??????
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN
Josefbloe
Posts: 4
Joined: 7 years ago
Location: Northern NSW Australia

#3

Post by Josefbloe »

Thanks for your reply......The next question is supposing the amps are higher, the original electrics is 12v/40amps and a replacement is maybe 12v/50amps, so does this matter? Another question is can I take off the vacuum pump and join the oil hoses together so can move this move the vehicle a short distance on the property where I live. I know that the brakes will be affected by doing this but I don't want to damage the engine. The alternator still works but the spline shaft that drives the vacuum pump has unbelievably sheared off almost as cleanly as if it were cut off so the pump doesn't work and it leaks oil
elminero67
Posts: 143
Joined: 11 years ago

#4

Post by elminero67 »

Looking at pictures the SD22 and SD23 alternator looks the same (I'll know for sure when my SD23 gets here). As mentioned the SD22 alternator was rated at 40 amps, I believe some of the later (SD25) alternators are rated higher. This is simply the maximum output, it will not hurt anything if you switch to a higher output, in fact it will help as the stock 40 amp alternator struggles to keep up if you have headlights, heater etc going at the same time.

Also, you can disconnect the vacuum line from the alternator without harm. The brake pedal will be harder to press, but still works.
plenzen
Posts: 869
Joined: 14 years ago
Location: Cochrane Alberta Canada

#5

Post by plenzen »

And YES !
You absolutely CAN join the two oil lines together. One is pressure IN and the other is the OUT line that runs back into the block just above the oil pan.

Make sure you clamp them well where you join them otherwise it will blow off.

In fact

Once you have joined them together start and run the engine and rev it up to see that it's not going to blow off.

I suspect that something went awry in the vacuum pump to cause the shaft to break off.

There is an alternative to this pump should you decide to do it.
An electric vacuum pump and a small accumulator. There is a post on here somewhere I think that Al ( asavage ) did some time ago. In fact I think he may still have a vacuum pump available.

I am a bit busy now but use the "search" feature of the forum and find it.

What I am saying is that it's not the end of the world.

Should you decide to do this then ANY alternator that has the correct output can be fitted and used. Motorola, Delco, Hitachi etc etc.

Simply remove the oil pressure line and plug it as well as the "drain" tube.

Good luck
Paul
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN
Josefbloe
Posts: 4
Joined: 7 years ago
Location: Northern NSW Australia

Are the sd22 and sd23 alternators specs the same?

#6

Post by Josefbloe »

I'm still trying to track down the exact specs for the 1986 Nissan Urvan (E23 series) SD23 alternator as new alts are available from China but there are different flavors depending on the vehicle.
I know the specs for the SD22 (LT140-107) which i got from my Nissan service manual bur it doesn't cover the SD23 engine, only the SD22 so can anybody help with with the specs.
So far I have found that the specs have to be 12v 40+amps and 80mm between the lower locating lugs where it's attached to the engine and the electric plug is the 130 type
Josefbloe
Posts: 4
Joined: 7 years ago
Location: Northern NSW Australia

Are the sd22 and sd23 alternators specs the same?

#7

Post by Josefbloe »

I'm still trying to track down the exact specs for the 1986 Nissan Urvan (E23 series) SD23 alternator as new alts are available from China but there are different flavors depending on the vehicle.
I know the specs for the SD22 (LT140-107) which i got from my Nissan service manual bur it doesn't cover the SD23 engine, only the SD22 so can anybody help with with the specs.
So far I have found that the specs have to be 12v 40+amps and 80mm between the lower locating lugs where it's attached to the engine, it is a single pulley and the electric plug is the 130 type
Last edited by Josefbloe 7 years ago, edited 1 time in total.
elminero67
Posts: 143
Joined: 11 years ago

#8

Post by elminero67 »

I have an SD23 arriving this weekend, will compare side by side and see.
Josefbloe
Posts: 4
Joined: 7 years ago
Location: Northern NSW Australia

#9

Post by Josefbloe »

That sounds great Elminero67, on a somewhat different track I have stumbled across an alternator from an Isuzu truck, checked the headlamp bulbs and they were 24v but other than that the alternator looks identical to the old one I have.
I've also taken it apart and the inside is also identical so my question is this. Can a vehicle have a 12v alternator and run a 24v system? (this truck has two batteries) I'm no expert on electrics so don't know what can be done or not as the case may be.
elminero67
Posts: 143
Joined: 11 years ago

#10

Post by elminero67 »

I just swapped a SD22 alternator onto my SD23. They are not exactly the same: The threaded oil line that goes from the alternator to the block has different threads on the alternator side. The Sd23 is a fine thread, the SD22 is a course thread-so if you swap you'll want to get that oil line with it. The second difference is the output plug, same thing, you'll want to get the output plug that comes with the alternator and splice it, its only three wires, should be easy to figure out.
Don't know anything about a 12v alt and a 24 volt system, sounds wonky.
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