NissanDiesel Forums

Whoopee! my transmission is shot. Of course i discovered that 400 km from home. It runs rough in gears 1,2,3 and okay in 4,5. The tranny oil is black and gritty. Lucky I have a parts truck and the previous owner says the tranny is fine in there. Between this and replacing the rings, looks like my truck will be off the road for a while.

Does your SD25 need rings?

Well, that's still to be determined. The truck is in my shop and I am almost ready to start checking it out. I'll compression test it real soon.

i had a look at the truck and the manual, and it seems swapping trannys might be not-so-bad. if i can change a head gasket, i guess i can swap a tranny. naive?

The early 720s have a welded-in rear crossmember, which makes R&R the trans a PITA. I hope the D21 went to a bolt-in rear crossmember.

the crossmember that is directly under the transmission is bolted in! i guess its mainly a matter of unbolting the tranny and bolting in the new one, and a couple of wires and the speedo cable. like changing a starter only bigger and heavier. (thats one way to psych myself up for this)

so i have unbolted everything and its all out of the way. the tranny has come back a couple of inches but it wont completely separate and drop down. i followed everything according to the fsm (thank goodness the exhaust doesnt have to be separated from the tranny on the D21) except maybe one thing. the fsm says drop the transmission enough to reach and unbolt the control housing. im not sure what the control housing is and whether or not i already unbolted it. any advice?

Sure your shifter isnt holding it back? I cant think of anything else you might miss. It may be possible that you have to just the body up some. I dont remember anything special thought when I pull the tranny from the pathfinder.

the shifter is out. i cant see anything in the way.

I can't find where you've mentioned: is your D21 2WD or 4WD?

I don't know what a "control housing" is either.

Not having experience doing this job on a D21 (I have done it on a 720), I can only offer generic advice. Remove the transmission rear mount. Speedo cable. Wire harness to neutral switch and reverse switch. Unbolt slave cylinder. Perhaps a lower rock shield on the bellhousing. Remove shifter lever from housing at pivot pin (requires removing console). Remove cab filler plate around shifter boot from floor so the trans can move back far enough.

That's all I can think of, but again, I do not know the D21 . . .


[ . . . other than a starter replacement I did on a '95 2.4l AT 2WD that was a hell job, last fall. It was the second starter for that rig in three years. Don't buy a cheap reman starter for one of these -- the man didn't take my advice the first time, but did the second time, since I charged him double what I did the first time.]

its a 2WD, as far as i know there isnt a diesel D21 4WD(if you see one for sale, let me know!) like i said i followed the instructions in the FSM which is the same as those instructions you just posted. i shook the hell out of it last night to see if would come loose, but to no avail.
should i be worried about breaking bending or otherwise mangling anything important/expensive/hard to replace?

[ . . . other than a starter replacement I did on a '95 2.4l AT 2WD that was a hell job, last fall. It was the second starter for that rig in three years. Don't buy a cheap reman starter for one of these -- the man didn't take my advice the first time, but did the second time, since I charged him double what I did the first time.]

the starter replacement ain't bad on my rig. ive done it a few times, when i rebuilt the head, and before that becuase the clutch in it wore out twice

it can get stuck on the clutch spline. as you slide it back it drags the dust into the spline binding it up. the later in backward clutches have a long area of spline in front of the clutch disc that rusts.i also had spigot bearings fall out or because too much grease was added the bush is seized on to the gear box shaft.

getting violent can bend the input shaft.or crack the thrust bearing guide.

I have had to remove the fork out of the way then unbolt the pressure plate though the hole.

i'm guessing you mean that it comes back but not enough to lower down.
if this is the case and its out of the spline then you raise or lower the front of the engine or remove engine mounts.

rubber hose for the trans breather tube.a silly wiring earth lead.an alignment dowel. small bolts in tin covers between eng/trans.

i did finally get it off, just played around with with it a bit more

i got 2 trannys and thus two throw out bearings. does each need to stay w/ its transmission? one, when i spin it , spins freely with a little sound of grit or something. the other only turns a bit before it stops but its quiet. should the one i use be greased?

i was reminded that the clutch and bearing in my truck were replaced brand new less than 2 yeas ago. so that answers my question.

im gonna wait to replace the tranny till i work out the oil burning problem. so i guess im taking the engine out or something like that