I've had my '87 240 for just 6 months. It has 123,000 mi. I got it at the Goodwill auto auction for $75.00. It was a wreck.
Here is what I have done:

replaced 3 engine mounts, new ball joints
rear brakes
new distributor, wires, and platnum bosch plugs
fixed a vacuum leak that was causing the engine to run rough and lose power
replaced the fuel relay twice
windshield wiper motor

Something is still wrong with it-
it uses three times a such gas as my '93 240 wagon.
It has a hard brake pedal if you brake more than once in a short period of time
It makes a distinctive sucking noise when you turn the engine off.

I assume it must be a vacuum related problem, but don't know what to look for. Has anyone had a car that makes that "sucking" noise?

I would have given the car away 3 months ago if it weren't for brickboard! I want to give this car to my 16 year old son. I'm trying to learn enough to show him that he can learn to fix it himself. I know how to fix computers but this is my first attempt at fixing cars. Thanks in advance.