4t60e fails to engage in all gears

[FGirdich]

Hey, I'm new to this, but I really need a place to start. I own a 98 Buick Century, 3.1L. 135,000 miles. driving conditions are normal, but drive the mountains between WV and VA about 3 times a month.
Noticed an occassional delay in shifting between 2nd and 3rd, so I had the fluid changed by tranny shop about a month ago, nothing out of the ordinary in the pan. Fast forward a month, driving down interstate in WV using cruise control (CC), getting ready to get on the off ramp, touched the brakes to release CC, CC disengaged, applied the gas to continue off the highway, and the tranny acted like it wasn't there. There was no sign of failure, no mechanical noises, no blow fuses. The linkage is intact, there is a slight burned odor from the fluid. When I shift it into any gear, no sign of engagement, not in reverse or any of the drive gears, nothing even if the RPMs are increased. After beign towed home, I let it cool, then checked the fluid prior to starting it up. One started and running for a few minutes, I checked the fluid level again, and there was no change in level. I work in VA and commute home on the weekends so my time is limited. I plan to have diagnostics run on it, but is there anything else I can check, and any idea what may be causing this. Really appreciate any help with this.

Frank

[chrisj]

Instant failure usually means that a shaft has broken or there is some other mechanical failure. If the oil level doesn't change, I would suspect the oil pump drive shaft is broken. The pump is driven by a separate shaft instead of from the rear of the converter like RWD cars. In any event, it will have to come out (sorry).

Chris

[FGirdich]

Instant failure usually means that a shaft has broken or there is some other mechanical failure. If the oil level doesn't change, I would suspect the oil pump drive shaft is broken. The pump is driven by a separate shaft instead of from the rear of the converter like RWD cars. In any event, it will have to come out (sorry).

Chris

Is there anything WRT the selonoids that I can check prior to pulling it? Thanks for the info.

Frank

[68 Custom]

Perform a 'line pressure test' to see if the transaxle is creating operational hydraulic pressure. The line pressure tap is located on top of the transaxle near the air vent. (I'm assuming a 4T60E, not a 4T65E, 1998 was kind of a crossover year)

I believe the fitting is 1/8" pipe and connects to a gauge. If no pressure, you probably have something stripped off between the torque converter, pump shaft or pump rotor.

If you do have pressure, around 100 psi, and it changes with vacuum changes to the modulator. You probably have a broken torque converter.

The only other thing would be if the 'input' clutch took a dump. The input clutch is used in all forward gears and reverse as well.

Let me know how it turns out...