I have a 1979 k10 with a turbo 350 automatic transmission. It used to drive before I parked for a while to work on it. When I went to drive it again, it wouldn't move. no forward or reverse gears. I checked the linkage to the transfer case and transmission and the linkage is fine. I checked to see it was even engaging each gear by putting it in a gear and pushing it and everything seems to be in order, it wouldn't roll in park and it would roll both ways in the respective gear as it should. The only thing I did to the transmission is change the fluid and filter. I didn't flush it just changed what drained in the pan. What could be wrong?
It sounds like the torque converter is not working. Is there a difference in engine idle speed when in park and in drive?
no
@memphismcgee
Can you please go into detail how you performed the fluid change? Perhaps you may have underfilled it...
I changed the fluid and filter because I changed the gasket since the old one was leaking. About a 4 quarts of fluid drained out when I removed the pan. I replaced the filter and the gasket that goes with it, then I put the pan with the new gasket on and torqued all the bolts to spec. I put the remainder of a bottle of fluid in which was about 3-3.5 quarts, then a little later I started it up so I could check the fluid level. I've added maybe another 1/2 quart but the dip stick is hard to read and I don't want to overfill it.
@memphismcgee
Ok, so it could be that the transmission needs more fluid. Automatic transmissions operate off hydraulic pressure which the ATF provides, so having a low amount of ATF will not engage the clutch pistons due to low hydraulic pressure.
BUT it could also be that the transmission is slipping after the new fluid change because the clutch-packs are severely worn out. The old fluid was providing friction for the worn out clutch-packs, but the new fluid may be causing it to slip. When was the last time you changed the ATF on this transmission? And what was the condition of the drained fluid (red, brown, burnt smell, etc.)?
I don't know when the last time the fluid was changed, I got it about a year ago, and I only drove it once before I started working on it, and it seemed perfectly fine. For all I know the fluid could be as old as the truck. the fluid that drained out was dark, but it still a little red color to it, and the consistency seemed the same as the new fluid I put in. there wasn't any burnt smell