1995 WhiteGMC 10-speed will shift good when the engine is cold, but after running for awhile, it gets to where it grinds really bad and is also harder to put into gear. Also, when it's in 3rd or 4th gear (can't remember which), it has a tendency to jump out of gear and back into neutral. What could be the problem? :?

 

The jumping out of gear is the detent spring is broken, as for the hard shifting, it is all related. i think your tranny is due for a overhaul.

The shifting good has nothing to do with the engine being cold, it has to do with the tranny fluid being cold and thick which cushions the problems in your tranny. When it is cold and thick it will work better until the fluid gets warm and thins out, then your symptoms you describe start happening.

You should get it in the shop before it leaves you stranded.

Good Luck.

 

Actually, I don't think it is a defective detent spring that's causing it to jump out of gear.

More like the sliders (the parts where the actual shifting takes place, the sliders engage the various gears with the mainshaft to give you the ratio which you're shifting into) have become worn to the point where the teeth are so shallow that they cannot stay engaged under high torque and therefore push apart causing the trans to jump out of gear.

Keep in mind that when you "grind gears", you're actually grinding the sliders (technical term: sliding clutches). Grind or jam them enough and they become worn to the point where they will no longer stay engaged when the power is on.

I agree that the tranny will need to be overhauled.

 

if you cant afford to rebuilt trans right now try draining trans fluid & put in 1-to 1-1/2 gallons of lucas oil stabilizer. a frined of mine did this & his noise & prob went away long enough for him to make enough money to get trans rebuilt.