'87 300TD, tranny shifts late and won't go into 4th gear
 

My wife's TD's tranny is acting up. This has happened in the past, but cleared up on it's own. Now it is doing it again. I am suspecting a vaccuum problem but I'll take any advice. She is shifting real late and it won't go into 4 gear. I checked the tranny fluid and it is fine. Any ideas?

On your transmission vacuum controls shift feel, hard of soft only, shift timing is controlled by the Bowden cable. Disconnect the cable from the throttle lever, the transmission should now shift early and stacked, one shift right after the other. If it shifts early, the cable was too tight, make the cable longer; adjust it with more slack (loose) in the cable.

Thanks for the tip. So the tranny will shift even if this cable is disconnected?

Correct, the Bowden cable is also called the control pressure cable, its function is to counter act, balance other pressures in the valve body, which are used to move valves that controls a particular shift. By removing that counter balancing force, the shift valves are free to move with no opposing force that controls shift timing.

The problem can still be the kick down solenoid, a stuck valve in the valve body, a leak in the B2 piston and K2 drum can cause no 4th Gear.

This is an easy test to eliminate control pressure as the cause for a late and no 4th shift.

I hope like hell it's simply an adjustment problem with the cable. We just recetnly spent some $$$$$ on replacing the head gasket and a few other "while you're there", things. We also just paid to have the odometer repaired (stop counting miles all together).

My wife drove her car to work today and it was still acting up on the way to work, but hse just got home and everything was fine. Being that a cable is mechanical, could the cable be bad out of adjustment one minuteand ok the next?