Hi all,
have a 86 240 dl wagon with manual tranny/overdrive. Problem is that while cruising along the overdrive just pops out and back in sparodiclly.

 

when this happened to me it was a relay problem for the O/D. But that was an auto. I don't even know if you have a relay.

But my haynes manual tells you do have a solenoid for it, so it might have a relay. If that's the case I would start by checking the relay for damage and maybe jumping the terminals for a day and seeing if that stops the problem.

If I'm wrong and you have no relay, check that the solenoid is getting power by (haynes manual instructions follow) Solenoid is mounted on the left side of the O/D unit, turn the ignition On, shift into fourth and engage O/D, verify there's voltage in the yellow wire at the solenoid. If there you can also check it manually by taking it off, blocking the holes between the o-rings and blowing air through the short end. There should no air leaking.

If it's none of those... well then you're o/d is likely shot.

 

Thanks...there is a relay so I will start there.

 

Yup, you have a relay. Last year for the M46. 87 saw the true 5 speed M47. While the relay is a good place to start if it continues, take a good look at the wireing under the car. There is a single wire that runs from the od solenoid to inside the car. The insulation on this wire takes a lot of abuse from leaking fluids and road debris. I've seen the wire be devoid of insulation for several inches causing it to ground and unground intermittently.