Have a 1987 420SEL with 170K miles. Transmission problems are new to me so I'd like a few pointers before I take the car to a shop.
Occasionally the transmission doesn't want to upshift from 2nd to 3rd or from 3rd to 4th. It may work fine for a few days, then start giving upshifting problems again. This problem often is brought on by making a right turn. Weird, huh? I can sometimes cure the problem temporarily by stopping, then shifting briefly into reverse, then going forward again. Once the problem starts, say by not upshifting from 3rd to 4th at freeway speed, it won't cure itself. I have to stop and do the reverse trick.
Any suggestions would be appreciated. I don't know if I'm ready to pay a large transmission repair bill for this old car.