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My 81' 720 Daily Diesel Died, Researching Options


Logical1

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Been a while Ratto's! I picked up a 81' 720 Diesel with the SD22 about 2 years ago. It was a smokey slow bitch but I loved her dearly. I commute crazy miles for work and just after I hit 200k on the odometer she started knocking really badly. (yes I know its a diesel & I kept fresh oil and water in it) It lost about half its power, was a bitch to start and was smoking like a chimney, Checked the oil and water and neither had any contamination. It wasn't burning oil that much faster that it had been over the years and not over heating. This led me to think the rings had failed and it just wasn't reaching the compression it needed. I don't think its the head gasket but I ordered one anyway (hasn't arrived yet).  From my research the 81 SD22 has 3 rings on the pistons and I haven't been able to find a 3 ring kit. However Even If I could I don't have the time to do a full rebuild right now. That being said I loved the diesel for the mileage even though it was the slowest beast ever. I wouldn't mind re-building the diesel in the future...However I need to get this truck back on the road asap, so some questions:

 

1. Does a L-Series bolt into the 720? not looking to use the diesel trans, wondering if I can pick up a L-series engine/tranny and drop it in. (motor mounts?)

 

2. If a L-series bolts up, is there a specific oil pan for the fit? the sd22 has a raised part in the middle of the pan for the crossmember.

 

3. If the L-series bolts up , is there a tranny that doesn't require driveline alteration? 

 

4. I know the napz motors are normally in these trucks, Not a huge fan of the napz series. is there any other motors that bolt in?

 

5. Is it worth it to hold onto the SD22 and rebuild it? seems like parts are becoming unobtanium these days.

 

I'm looking for the easiest, cheapest, fastest route to a work truck. Should I try and resurrect the 720 or just find a cheap 620 and start back into my comfort zone of Gasoline and older models ;)

 

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Only a diesel bolts in to the diesel frame, the mounts on the frame are farther forward, but I have never had a reason to try and put a napZ engine into a diesel frame.

 

The L series front case will bolt onto the diesel engine transmission, that front diesel transmission case is valuable, do not throw it away, lots of folks are looking for them cases.

 

You will need the 720 oil pan for what ever engine you use, a late 620 L20b disc brake truck oil pan may work, I have never tried using one though.

 

Any L series 5 speed transmission will bolt into the 720 frame, but the engine mounted to it will need frame mounts made, or an adapter made that uses the diesel mounts.

 

There is a guy down here selling a diesel engine on craigslist, I don't see it listed right now, but he wanted $600.00 for it, I have a rebuilt one also, but I want way more than that for it, I do know the guy selling that used engine and can contact him if you are interested.

 

There is a company in China that sells 3 ring rebuild kits, but I cannot remember if they had SD22 kits, as I only look at the SD25 stuff anymore, as I have SD25s in my trucks, I even turbocharged one.

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check with these guys. they might have an old set laying around

 

http://nissandiesel.dyndns.org/index.php?sid=a1750ba610b3a6087a3c4380954d50d7

 

 

my wife always reminds me... cheap sometimes expensive.

 

I'de fix what you got. Bare minimum.... change the rings on that one cylinder with the engine in the truck if you don't have a hoist and a shop to work on it. Did anyone ever use ether to start the truck? That will blow the rings to pieces fast.

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