Ive been having a problem recently with my transmission. I'm driving a 1998 Ranger 4x4, manual 5 speed tranny. It has just over 250,000 on it. The past month I have been experiencing a grind sound when shifting into 3rd(this is the most troublesome gear) I'm babying it now, and have narrowed it down to rpm's. I have to be shifting to 3rd at just under 2k or it will grind. Had the oil changed about a week ago and they checked the tranny fluid. it was not low and could be changed out, but not a dire emergency. Besides, I have heard that if the fluid has not been changed in a while, it could do more harm if flushing and refilling it. I am not sure if this is related, but when pushing in the clutch, even at a dead stop, the rpm's will jump up about a 1,000 then drop back down. when driving, and I go to shift from 2nd to 3rd, i'll push the clutch in and sometimes it will jump to 2k. at this point, I have to shift to 4th and back into 3rd to avoid grinding/ forcing it into 3rd. I am not sure if the clutch is going out, the syncro's are slowly going or what. With the age and mileage of the vehicle, it would not be cost effective for me to replace any part of the tranny....if im in that far the engine could be replaced as well. but then it could be time for a new truck.
Any help would be appreciated.

 

What engine do you have?

Transmission problem will require a rebuild or swap, not a clutch issue
You have an M5OD-R1(M5R1) transmission, very reliable 5-speed, used from 1988 to 2012 in Rangers
A used M5R1 is not a big gamble
But M5R1 is engine specific since bell housing doesn't detach, and must be a 4x4 model for your use
So if you have a 3.0l engine you can only use an M5R1 from a 3.0l 4x4 Ranger or Mazda B3000 4x4


The RPMs should hang when shifting that is normal, but not go up 1,000rpms, that is not normal
After engine is warmed up, let it idle and unplug the IAC Valves 2 wire connector
Idle should drop to 500rpms, or engine may even stall, either is GOOD, no vacuum leaks
If idle doesn't drop then look for leaks and also remove IAC Valve and clean it
This is unrelated to transmission issues


Transmission always spins at rear wheel/drive shaft RPMs, there is no disconnect for that
The clutch disconnects engine RPMs from transmission/rear wheel RPMs
In the old days you needed to push in the clutch pedal and then RPM MATCH the engine RPMs to transmission/rear wheel RPMs or gear would grind like crazy, this is what you are doing to keep the grinding to a minimum
Synchromesh was invented so novices didn't need to RPM MATCH when shifting, it was an "art", lol
The Synchro is a "gear" of softer metal that matches RPMs as you push stick shift into a gear, so it slows down or speeds up the Clutch disc to match trans/rear wheel RPMs
The M5R1 has a synchro gear on all 6 gears, reverse as well as 5 forward gears

Your 3rd gear synchro is bad, and probably the 3/4 shift fork is worn which causes it to pop out of 4th

There are 3 shift forks used to select the 6 gears
1/2
3/4
5/R

The shift fork can be changed fairly easy but the synchro would require a complete tear down