Please school me on the SD22

[minipigg]

Hi,

I found an 1982 Nissan truck with SD22 and I think it was a 4x4. Anyway the truck doesnt run. He wants 500 bucks. Im interested but know nothing about the SD22. Just curious how it compares to the Mercedes 240D and if I can find parts to rebuild the engine.

[asavage]

Hello, Minipigg, and Welcome to our Sandbox!

I found an 1982 Nissan truck with SD22 and I think it was a 4x4.

While there are some 4WD SD22-powered 720s running around the US, none of them were imported, and TTBOMK none were manufactured anywhere. If yours is truly 4WD, it's one of the conversions.

Anyway the truck doesnt run. He wants 500 bucks. Im interested but know nothing about the SD22.

Buying a vehicle that does not run requires that you be willing to take a gamble. If the price is right, the gamble becomes less. Or, if you bring significant knowledge to a non-running vehicle (ie you know or are certain what is the most significant problem, or you have another buyer to take it off your hands at a profit, etc.), the gamble is lessened.

However, realistically you have to assume the worst. You can't check the suspension, the transmission(s), the brakes, etc. All of these 24-yr-old subsystems are likely to need attention to some degree, esp. the transmission, but you are unable to ascertain the degree if you can't drive it.

Just curious how it compares to the Mercedes 240D and if I can find parts to rebuild the engine.

Rebuild parts are plentiful and a lot cheaper than the rebuild parts for the 240D. However, in this price class, you don't want to be considering rebuilding -- either engine would cost more to properly rebuild than most of the vehicles to which they are fitted are worth!

The power output is comparable. Mileage is probably slightly better with the SD. Both utilize inline injection pumps. The SD has agricultural origins and was a proven design (over fifteen years in production) by the time Nissan fitted it to the 720 PU. The 240D has proven to be a very reliable and moderately durable engine that is expensive to repair and needs attention to the head if overheated -- or even if not.

They are both good, small diesel engines. The SD is a bit easier to work on IMO, though the pneumatic governor combined with the IP controller can require a little study to troubleshoot -- but the Factory Service Manual plus Philip's articles will make that a snap. The 240D is a bit more car-like in output; the SD takes some getting used to, but once accustomed to it you'll find it tractable and a reasonable driving companion. The 240D likes the upper revs more than the SD; the SD may make a bit more torque off the line.

These are only surface impressions, of course. I would be hesitant to invest $500 in a vintage diesel that I can't hear run or at least perform a compression test on, unless I was quite certain of its history and the availability of another engine in the worst case -- and the truck would have to be extremely well kept at that price, for a non-runner.

As examples, I purchased an '82 720 diesel PU two years ago for $400, with 86k original miles, bad transmission, decent chassis. I could hear it run before handing over the money, but I couldn't drive it, so I was taking a chance on the suspension, rear end, brakes etc. It turned out quite nicely after considerable work (see the FS5W71b transmission thread). SD transmissions are getting rare in good condition, and they do break.

Later, I bought an extremely rusty '82 720 diesel PU (non-runner, 2xxk miles) for $160 for a friend. Mismatched bed, floors gone, it became a very decent runner after I spent a very modest amount of time and effort undoing what the kids who owned it had done to the fuel system and IPC. It's being driven now as a sort of "beater" diesel PU, but I got lucky on that engine. The trans is quite worn. Friend is looking for another decent cab/frame to transplant his engine into.

A month ago I picked up a third '82 for free, blown engine and no title but a good transmission etc. Cost me $100 to haul it home (search on "Vashon" to read about the trip and see photos). Parts rig, most likely, but factory sunroof! Hole blown in bottom AND top of engine.

[minipigg]

What kind of mileage do they average? My 1983 240D was extremely reliable after I tuned it up and worked thru some bugs. Could I expect the same from the SD22?

[asavage]

What kind of mileage do they average?

I got 33-35 MPG on ASTM D6751 biodiesel. Most folks seem to hover around 35 MPG or thereabouts. Philip can get 40 MPG on some of his highway trips.

My 1983 240D was extremely reliable after I tuned it up and worked thru some bugs. Could I expect the same from the SD22?

Yes. The SD22 does not have much in the way of weak areas, aside from perhaps the DPC controller (solder joints mainly) and sometimes the IPC motor. If you understand how it functions, you can easily disconnect it and drive it until you can obtain spares with no significant downside. The engine is very durable. The alternator should receive preventative maintenance (ie brushes) before it gives signs of trouble; this will save you money in the long run. There is no vacuum pump diaphragm as is used in the 240D, and the vane-type vacuum pump (on the rear of the alternator) never seems to give any trouble.

Changing the fuel filter is barely easier than on the 240D (same priming plunger setup), but the fuel filter will likely need to be ordered in advance, as few places keep it in stock. It is easily available. See the "Fuel filters" thread for differences & details.

OTOH, you will want to change the transmission oil on a schedule with premium gear oil and not let it become contaminated with debris, whether externally or internally generated.