My husband's 82' 240 DL wagon (4spd manual with push button overdrive) has developed a bizarre problem. The overdrive doesn't want to engage when the button is pushed. Our mechanic told us the likely culprit was the relay located behind the center console, so we replaced it. This has resulted in making the audible "click" into overdrive quieter but no more reliable. The car only seems to have a problem engaging OD after it gets warmed up, when the car is cold the 5th speed works fine. It either will not go into OD, shudders violently under acceleration or makes you wait for many seconds then drops with a "clunk" into OD. The car has jumped out of OD before too, this also only happens after the car is driven for awhile. The light on the dash is always illuminated when the button is pressed. I am at a loss as to what is wrong with the car. Any help you can give me would be appreciated.