1990 Pathfinder HELP!

[Prospeeder]

Hey I need some help asap. I have a friend with a 1990 Nissan Pathfinder and its a 4x4 5 speed manual. It is like locked in gear. You put it in nuetral and it goes forward. And you can go through every gear with it off or on just fine, like the spots are still there, the shifters not all sloppy. And the wierd thing, you go into reverse, and the car doesnt move at all, but it kills the engine as if it was in gear. Did the tranny finally give up the ghost (it grinded into 2nd and 4th, popped out of 1st bad, and 3rd is gone) this is his only transportation and he needs it abit longer. Do these have linkages that go out of wack or anything? It worked just fine yesterday, now thismorning its like that.

[4x4_Welder]

If he beat on it, or slammed it into gear, or yanked it out of gear without using the clutch, chances are it has a broken shift fork or shift rail. The Aisin transmissions both Nissan and Toyota used were good for this, I had a five speed in a 94 3/4 ton 2wd that first broke a fork, then broke that same rail a few months later.

Not too hard of a fix if you've had manual trannies apart before, both times I tore mine down on the porch of my apartment.

 

Another thought is the plastic ball on the bottom of the shifter may be worn out, this bushing isolates the shifter so you don't hear the tranny as much. If this wears out, it is possible to get the tranny into two gears at once, or not fully engage gears.

[Prospeeder]

Hmm alright thanks, how apparent is it to see if the ball on the shifter is too worn out.

[4x4_Welder]

If the shifter has lots of slop, and really vague feel-

Pull the boot and insulator up the shifter, there should be a little rubber boot around the shifter on the tranny. Pull that up, and there is a little stamped steel piece that holds the shifter in place in the tranny. Push this down and turn 1/4turn ccw, then pull the shifter up and out of the tranny. If there is a white plastic ball on the end of the shifter, and the slots in the three rods line up, that's not your problem.

 

Bear in mind, this may have a slightly different style shifter, so you may want to consult a manual.

[Nug]

One shift fork is constantly engaging a gear. That's why neutral is acting like a gear. When you do to shift into another gear, you are engaging two gears at once. This is like dividing by zero. You can't do that. Tranny no likey. It effectively locks it up.

 

If it's of the design where the top of the transmission can be unbolted and the shifter and all the shift forks are removed in one go, then you can probably fix it no problem. If it's of the design that just the shifter can be removed and all of the shift rails and forks can only be removed with some major disassembly, then you might be screwed as far as an easy fix is concerned.

Essentially, all of the shift forks engage a sliding collar. When the collar slides one way or another, they engage gears. You've got a collar that won't return to its center, its neutral position. This can be because a shift fork is bent, there is wear on the detents of the shifter shafts, or because the end of the shifter (or the ends of the shift shafts themselves) are worn. Pull the shifter out and look in. Are all of the shifter shafts lined up? There should be three of them. Is one out of position? Try to pry it back with a screwdriver. If the shifter shafts are all in line and it still does it, then I'd suspect a bent/broken shift fork or maybe a sheared roll pin between a shift fork and shaft. If the shift shafts are not lined up and you are able to move it back into position, and it works normally, then I would tell your friend to shif the truck slowly in an exaggerated H-pattern. Not moving the shifter in a straight line from second to third, for example. move the shifter up, then right, then up again. This will keep the worn components from accidently engaging things they aren't supposed to.

 

This happened to me on the BABE rally in may. Furiously working the shifer back and forth fixed it (don't do that).

 

The above rambling makes sense. To me, anyway.

[4x4_Welder]

It -should- be an Aisin tranny just like the one in my old Toy- Separate bell housing, aluminum front section, cast steel center bearing plate, and aluminum rear section. Stand the tranny on the bell housing end (you have to set it on a couple 2x4s to clear the input shaft), take the bolts out that hold the three pieces together, and separate the rear section off the center plate. Of course, that would have to be the only way to get in there to inspect the shift rails and forks anyways.