1994 gmc sierra transmission, torque convertor? noise in park, neutral and reverse.

[94GMC45]

recently my 1994 GMC x-cab 350ci auto-4 spd 216000 miles, started making loud clanking noises when i shifted into reverse. then it began the proceeding day to do the same loud noise in neutral, and once driven even in park. what puzzles me is that in drive it shifts and drives fine with no noises. to better explain the noise and some of what is happening it sounds as when a uni-bearing in a drive shaft clanks and the drive shaft does sometimes attempt to rotate very fast back and forth while in park, neutral and reverse. but sometimes its only heard coming from the torque converter area of the tranny while in park. this sound resembles the noise of bad lower crank bearings. when driving in reverse it is as though something is binding up the engine making it strain or fight like a wore out drive shaft uni-joint. but the uni-joints do not have wear or play in them to cause the binding. any ideas? thanx.

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[RUFFNECK4LYFE]

Check your tranny fluid before starting it, then start it and see if the fluid level drops on the dip stick like it is supposed too.

[94GMC45]

Originally Posted by RUFFNECK4LYFE

Check your tranny fluid before starting it, then start it and see if the fluid level drops on the dip stick like it is supposed too.

thanx for the quick response. i checked the fluid level cold and it was way above the "cold" mark into the part of the dipstick where it forms a "z" like pattern. then i started it up and the level dropped to the "full hot" level after a few minutes warm up. on initial start up no noise, but again once i put it in reverse the noise began and continued in neutral and park. then after a few minutes the noise went away. when placed in drive all "noises" discontinued. the oil is a tad bit on the darker side, so i feel it does need to be replaced, but i worry that some bearing clutch plates etc or converter problem may exist. yet i do know that the torqe convertor always turns in the same direction. so the convertor operation in forward leads me to believe it maybe an internal tranny problem?

i consider myself a giant parts changer, not a mechanic.

ive had a 71 455 buick race build blueprint/balanced with hi-lift cam and JE pistons etc to 462 ci and t-400 trannys pro-built w/bearings and x-clutch plates for the torque/power. all i did was attach the parts after a real mechanic did the details, and i shoehorned it into a 1987 buick regal by myself.

[RUFFNECK4LYFE]

Well its hard to tell. Maybe put the rear on some jack stands and have someone start it and change gears to see if you can tell where the noise is coming from.

[94GMC45]

noise pretty much has gone away 'cept sometimes in reverse. but the "locking up and jerk-clank" is no longer present. just changed fluid & filter. but it had chunks of what apper to be seals gaskits or clutch plate material in the pan. dunno. are there any replacement such as a turbo 350/400 or older 700r4 long tail that will just bolt in. ya i do know that the passing gear link will present some prbs. but i'd really like to someday shoehorn the thing into my s-10 w/5 or 6 speed tranny. but i see all the x-tra challanges as far as hydr clutch linkage etc from my jtr manuel. and i only want a sleeper w cold a/c. i'd even trash the PC for a carb. even if it loses HP and burn more fuel.

[RUFFNECK4LYFE]

Any of those tranny's will work. The next year(95) they started putting in the 4l60E. Im not sure though. So I think you would be happy with a 700R4. Wont have to mess with the comp or nothing.