1988 gmc Manuel transmission clutch don't work

it could be as simple as a solenoid in the transmission or a mechanical issue best to find a friend that works at a shop and maybe they can give you a break on the diagnostics

Of course.

You don't have a clutch in that automatic, check your transmission fluid first. Make sure you run your truck for 10 min. or so before you check the fluid level. If your fluid is correct then take it to a mechanic, they can check your transmission with their computer and see exactly what is happening when it can't find 4th gear.

That line is your hydraulic clutch line which is attached to the clutch master cylinder. Look very closely, you will see a white plastic sleeve on the metal connector at the transmission end of this hose. you will need to gently push this toward the transmission. you will have to work on many sides as this piece is flexible. Once worked in all around. the line should pull out of the transmission.

Not too big of a deal. Disconnect battery.
Remove driveshaft from vehicle. Disconnect any electrical wiring from transmission. Remove starter. Remove gear shifter. Support transmission on a transmission jack, or a good sturdy floor jack. Remove rear transmission mount, and crossmember. Lower transmission slightly to help gain access to the engine-to-trans bolts. Unbolt slave cylinder and hang it out of the way. Remove engine-to-transmission bolts, and bouncer bars (if equipped) Slowly pull transmission away from engine. If it's stuck, double-check to make sure all the bolts are out, then try raising or lowering the trans a bit with the jack and/or pry in between with a pry bar to help break it loose. Remove transmission from vehicle. DON'T lose the dowel pins! They are needed to line up the engine to the trans properly. Remove clutch pressure plate from flywheel, and remove pressure plate, and clutch plate. If the rear main seal is leaking (behind flywheel) NOW is the time to change it (cheap $10 part) Installation is in reverse of removal. Good luck!!

That would be coolant from the radiator
trans cooler

Now you have to rebuild it again

What it sounds like is that your pilot bearing has gone out, and that could be causing the high pitch grinding noise and when the gears are hard to shift that is a tale tale sign of a bad/weak pressure plate and or master cylinder. I would recommend changing out the clutch, pilot bearing, pressure plate, slave cylinder and having the flywheel resurfaced.

The clutch or linkage needs repair.It happened on my Escort.It turned out to be linkage and was obviously much cheaper than a clutch.It sounds like linkage because even if the clutch was bad,it would kind of hesitate,rev strangely,be herky jerky,maybe even hard shift.Linkage problem is more like whatever gear you have is all you will get obviously because it is incapable to shift.Good luck! Greg

use a manuel will help but u need to drop the transmission