transmission grinding hard

[LemonLobster740]

I have a 1995 K1500 with the 5.7 engine and 5 speed manual transmission. I bought with around 170,000 miles, drove it about 10,000 miles, and now all gears are grinding when i try to put it in. It takes about 4 tries to even get it into 4th gear at this point, and it grinds LOUD every time. It started off only grinding sometimes when you put it in reverse but now it grinds first gear very bad. This issue just popped up yesterday randomly. It is also difficult to take the truck out of gear, and when it’s in neutral there is a loud humming sound coming from below the cab. Anyone know the issue?

 

[RichLo]

That'll be an NV3500. First step is drain and refill with good syncromesh trans fluid. AMSOIL makes good stuff, link below. Otherwise your clutch could still be engaged, is the master cylinder low? How is the pedal travel before engaging... is it right at the floor, in the middle, or way far at the end? Does the grinding get slightly better when the RPM's go down between shifts?

https://www.amsoil.com/p/amsoil-5w-30-manual-synchromesh-transmission-fluid-mtf/?code=MTFQT-EA&gad_source=1&gclid=CjwKCAiA_tuuBhAUEiwAvxkgTmX6vJoDt6JVSipBVW7cvhJeS4wVpBDeGoavMOqWZ4L8jesr2pAErhoC27UQAvD_BwE

 

[LemonLobster740]

That'll be an NV3500. First step is drain and refill with good syncromesh trans fluid. AMSOIL makes good stuff, link below. Otherwise your clutch could still be engaged, is the master cylinder low? How is the pedal travel before engaging... is it right at the floor, in the middle, or way far at the end? Does the grinding get slightly better when the RPM's go down between shifts?

https://www.amsoil.com/p/amsoil-5w-30-manual-synchromesh-transmission-fluid-mtf/?code=MTFQT-EA&gad_source=1&gclid=CjwKCAiA_tuuBhAUEiwAvxkgTmX6vJoDt6JVSipBVW7cvhJeS4wVpBDeGoavMOqWZ4L8jesr2pAErhoC27UQAvD_BwE

Clutch engages around half way depressed. I’ll drain & replace the trans fluid with that, and i’m not sure if this is a contributing factor- but as I press and release the clutch, it feels kind of rough and bumpy if you depress it slowly. I’m just very unfamiliar with transmission work so I haven’t checked anything/torn anything apart

 

[Erik the Awful]

Check your clutch hydraulics for leaks. If your clutch isn't fully disengaging because of a loss of hydraulic pressure, your transmission is still spinning and won't want to change gears. Bleed, bleed, bleed your clutch hydraulics.

If your clutch hydraulics are working correctly, your pilot bearing/bushing may be seizing up, keeping the transmission spinning even when you push the clutch pedal in.

The clutch feeling rough and bumpy when you press the pedal sounds like a release bearing going out.

 

[LemonLobster740]

Alright, thanks for your help. I’ll give it a shot tonight.