SD22 Rear main seal, styles, replacement, issues

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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dieselreaper
Posts: 1
Joined: 7 years ago
Location: oregon coast

SD22 Rear main seal, styles, replacement, issues

#1

Post by dieselreaper »

Hello, My name is Tony and I have acquired 2 Nissan sd22 engines. This is the first time I've dealt with Nissan diesels. Their quite simple but what I am having issues with is replacing the rear main seal. I've tried to find information on google and this form and all that I've come across is:
- They are 2 piece seasl stock
- when receiving a replacement 1 piece, you must press the flywheel bolting plate off the crankshaft. This requires a special tool
- There will always be a worn groove in the crank requiring a interference sleeve to be press on the crankshaft to seal properly
- If you aquire 1 2 piece seal, You can replace it by just removing the oil pan and rear main bearing cap, Remove old and push in new.

Do all these statements sound accurate to you Nissan gurus?
I'm pretty sure I can fab a device to bolt to that plate for pressing off the crank, but is it that difficult to remove(breaking plate or crank)?

I am doing a fast regasket on this motor so it can go back into my 86 hardbody and be my daily driver again. The other motor I will do a full rebuild on. Side question, I hear forklift style motors have 5 piston rings while truck engines had 3 rings. Mine came out of a generator so I am thinking it will be 5 ring, Is this right? Any import things I should know about this motor while I am reassembling it.

Much appreciated for all responses and knowledge sharing
plenzen
Posts: 869
Joined: 14 years ago
Location: Cochrane Alberta Canada

#2

Post by plenzen »

Rolling in a new 2 piece seal sounds like an easier way to go to me. After you press off the piece on the end of the crank you still have to dig the old seal out, and get that pressed piece back on. That can be filled with frustration and despair and end up removing the pan and rear main cap anyway. If it were me I would buy the 2 piece from the get go. There is a neat little trick for rolling the upper half of the seal out, and in, that works pretty well. That being said, using a 2 piece wont get the speedy sleeve over the end of the crank. Is it really worn that bad? If it is your stuck pulling that piece off the end of the crank anyway. ( although I cannot recall exactly how that part comes off or how its held in place )


You are correct and the industrial engines had 5 rings and a steel top ring land as well.
The fuel pump will also be different from automotive use but can be used in automotive application.
That being said, it will have to have the governor changed back from generator duties. The fuel settings and springs will have to be reverted back and the throttle lever locks readjusted, the governor can still be used just changed that's all.

Not certain if a "speedy sleeve" is available for the SD 22 crankshaft as that is about 3 1/2 inches in diameter. ( guess )
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN
bb top
Posts: 3
Joined: 8 years ago
Location: nova scotia

Re: SD22 Rear main seal, styles, replacement, issues

#3

Post by bb top »

Hello,
Any leads on where to buy the 2 piece rear main seal? Canada or U.S.?
plenzen
Posts: 869
Joined: 14 years ago
Location: Cochrane Alberta Canada

Re: SD22 Rear main seal, styles, replacement, issues

#4

Post by plenzen »

Unknown as that was his only post.
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN
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