Engine Swap

[doodoo]

Hello doodoo is new to this forum. Researching the idea of replacing the gas engine in a 1994 Nissan d21(automatic transmission) 4x4 with a Nissan diesel. Can any body give me some help? Thanks, doodoo.

[asavage]

Part of the answer to your Q will depend upon where in the world you reside -- you can add that info to your Profile by clicking on the "Profile" button at the top of any page.

The reason your location is important is that Nissan offered different diesel options in parts of the world other than the US where many of us are based. Offhand, I think that member Davehoos (who resides in Australia) may be able to be of help here. The D21 was offered in Canada only one year with the SD25 diesel option, and AFAIK the SD2x never was offered in North America with an automatic, and I know for certain that the bellhousing bolt pattern on the SD series is an SAE No. 3, which is different from the gasser engine you'll have in your D21. IOW the SD engine will not bolt up to your automatic transmission, AFAIK.

The 4x4 is another issue. On the older 720 (the predecessor to the D21/Hardbody series), in order to make the SD2x fit an oil pan needs to be fabricated, as the sump is in a different location on the 4x4 chassis. It's been done, at least twice that I'm aware of.

In parts of the world other than North America, Nissan offered a lot of different diesel engines, (Patrol, Urvan, etc.) and someone familiar with those models may be able to provide a lot better information. But if you live in the US or Canada/Mexico, and you want to convert your '94 D21 4x4 to diesel, the task sounds formidible.

[davehoos]

The TD engine family are commonly mated to L4N71B automatics in the urvan E24. Might be in some E23.

Pathfinder [Terano] 4X4. These are like later models and are fully electronic as is the engine. Cannot say I've seen SD powered vehicles with the option but, in japan anything is posible.

SD23 are common taxi engines in the cedric. But they are listed as manual trans. I found it strange when in Japan that the older taxi had basic manual trans with a very heavy duty servicable clutch.

Service data books in australia. We get Europe-general-Gulf standard-middle east, not japan domestic. Some of South East Asia [hong kong, singapore]. This does not include the Americas[except the islands] or africa [some is listed as Middle East others are South African full import models].

Countries like New Zealand get a mixture of Australian, Japanese, and English models. These mixtures are not included.

[philip]

I visited a scrap yard (Pick-a-Part) yesterday. Amazing how many 720 pickups are still finding their way to these yards after 20 yrs. Photos taken with my cell phone camera.

Anyway, one recurring question regarding swapping an SD22 for a gasoline engine is about motor mounts, particularly the right side.

I noticed that the welded frame bracket on this '82 is smaller than in a nearby '84 pickup. It would seem to me the '84 (not sure what happens in '83) would accomodate the SD's slightly different mounting point whereas I've heard some welding / fabrication is required when repowering an '82.

The 1982. Notice the width of the frame pad mount. No adjustability forward/aft.



The 1984. Notice the width of the frame pad mount. Much longer to accomodate TWO possible motor mount locations. This wider frame pad is also present in my 1982 diesel 720 !! Hmmm

[TheDieseliminator]

Anyway, one recurring question regarding swapping an SD22 for a gasoline engine is about motor mounts, particularly the right side.

I noticed that the welded frame bracket on an '82 is smaller than in an '84 pickup. It would seem to me the '84 (not sure what happens in '83) would accomodate the SD's slightly different mounting point whereas I've heard some welding / fabrication is required when repowering an '82.

Philip, this is just great information to learn after an informative trip to the junkyard. What I'm basically finding out is the 80-82 pickup is not the best candidate to convert to the diesel engine when it came factory as a gasoline model. But, the 83-86 pickup is the much better candidate given the evidence of the two pictures you posted. They are two excellent pictures by the way. I see for the 84 mounts that the whole frame pad mount can be unbolted and then moved to the left << (as in the picture) or toward the front of the truck. So does this mean if I were to buy an 83-86 gasoline truck I could convert it to the SD22/SD25 no problem? Or I mean will the diesel bolt right in on the mounts? This is what I've always wondered about the gas 720s. I know a member on the 720 owner's group converted an 81 or 82 gas truck to the SD22 and had to weld mounts. And in a Hardbody pickup I'm sure you'll have to do the same no matter what year given a diesel engine was never an option. But it seems for 83-86 720s (the middle point) it's able to finally be a "bolt-in" job, past all the fuel and electrical conversions you do from the truck being a factory gasoline model. That's a given in any gas-diesel conversion. Great info and pictures once again. Thanks for your reply too.

Salvy

[philip]

SNIP
Philip, this is just great information to learn after an informative trip to the junkyard. What I'm basically finding out is the 80-82 pickup is not the best candidate to convert to the diesel engine when it came factory as a gasoline model. But, the 83-86 pickup is the much better candidate given the evidence of the two pictures you posted. They are two excellent pictures by the way. I see for the 84 mounts that the whole frame pad mount can be unbolted and then moved to the left << (as in the picture) or toward the front of the truck. SNIP

Salvy

These trucks were slapped together with whatever was on hand to keep the assembly line moving. So it seems reasonable to me that you may well find an '82 gasoline truck with the wide right side pad.

My '82 SD22 truck (10/81 prod date) has the broad, adjustable frame pad. Note here with the SD22, the forward hole set is used whereas in my prior post, a gasoline truck used the rear hole set.

[asavage]

But it seems for 83-86 720s (the middle point) it's able to finally be a "bolt-in" job, past all the fuel and electrical conversions you do from the truck being a factory gasoline model.

It looks as if I'll be finding out -- Peter is fairly certain that he'll be putting his '82 SD engine/trans into the yellow '86 gasser this fall. I'll take pics, for sure.

Anybody need a decent running Z24 (carb) engine/5-spd? I'm at 98368.

[davehoos]

There is also a mount that uses the outer holes,with the square block mount at one end. I got one off an LD20T out of an early large van[homer/urvan]. These bolt up to the Cedric taxi and the 720. I welded the ends to a K-subframe on a GM-commodore conversion.

There are heavy duty frames. I guess this can alter construction.

[TheDieseliminator]

It looks as if I'll be finding out -- Peter is fairly certain that he'll be putting his '82 SD engine/trans into the yellow '86 gasser this fall. I'll take pics, for sure.

Al, I'll be looking forward to your progress with his truck. I'm thinking about doing the same thing with an 84, 85, or 86 truck. Pictures should really be great.

[DanielB]

I converted an 86's gas Nissan pickup to an SD25. All of my friends said I was crazy, but I think it was worth it. Getting the motor to sit in the right spot in the frame wasn't too tricky. I did a bit of welding for the mounts to fit right, but nothing too drastic. The hardest part was figuring out which wires were now unneeded (becuase they were for all the various computer type stuff for the gas engines), and which were nescesary.

[philip]

I converted an 86's gas Nissan pickup to an SD25. Getting the motor to sit in the right spot in the frame wasn't too tricky. I did a bit of welding for the mounts to fit right, but nothing too drastic. SNIP

Considering by '86 the SD engines had been a bolt-in for several years, there should have been no welding necessary at all ... provided you had the frame with the wide right side pad.

[idahocity]

hi community. maybe you could give me your $0.02 worth on this.

i have been inspecting my new purchase a little more closely it appears the corrosion may be more advanced than i first noticed. the driver side floor is almost 1/4 gone and the passenger side is close. i don't know if it is worth all the work to arrest the rust and fiberglass it. the frame is slightly rusty, the taillights are gerririgged, leaf springs shot, parking brake is broken, and a lugnut missing. that's just a preliminary inspection. i think my time might better be spent using the motor to repower a more rust resistant donor. I have seen posts that 84-86 nissans are close matches and even late 80's to early 90's model mazda pickup. if i go through all the trouble to repower I would like to make it a 4wd.
(Inhale)

Ideally it would be a king cab or prefferably an suv type candidate with minor customization, the easier the better. Reccomendations, make, model and difficulty. I live in a relatively isolated area so the more vehicle options the better, while cruising yards and classifieds.

I am not half the mechanic most of you are, but I think if I throw enough time, friends, bloody knuckles, and swear words at the project I could do it.

[asavage]

4WD conversion into a Nissan with the SD requires fabricating a custom oil pan, and I do mean custom. It's been done twice, that I know of. If you're really interested, I could try to find the pictures of that pan.

[idahocity]

I've read about the relative ease with which the engine will mount and the transmission can be modded. if the oil pan is the most difficult step, then i think it is very doable, as long as you can still use part of the original oil pan.
Anyway, there are quite a few capable metal workers i could shop that to.

Is it just the 84-87 model that will work? Is there a compatible suv, like a pathfinder? wasn't there an 86 or 87 pathfinder? an off the wall question: is there any similarity between the late 80's isuzu trooper diesel and the nissan diesels???

thanks for the input

[asavage]

How difficult is it to put a diesel engine into a gas 720?
What is the compatability like?

Radiator (I think). Possible motor mount plates, not really adapter but more like extenders, and possibly not needed on later frames. You positively *must* use the SD version of the FS5W71 transmission case (front half), as the gasser version won't come close to bolting up to an SD. However, see this thead for a cheap option, if you can only find a toasted SD transmission.

Fuel tank. The gasser one is probably galvanized inside; diesel + zinc = plugged filters etc., so you'll need a diesel version of the fuel tank, or coat the inside of the gasser's, or roll your own.

That, pretty much, summarizes the issues I think I'll be facing when I do a 1982 KC SD -> 1986 gasser conversion later this year.