I went and looked at an 88 M the other day and I know going in that the car needed engine work. The owner told me so. When i got there the car looked in pretty decent shape for the age of it. But, when i started the engine it made a slight diesel sound(timing chain) but that was the good noise. The engine made a very loud Knocking noise and that was accompanied by a hideous screaching sound that lasted throughout the rpm band. I only reved that engine to about 4000 rpm. It really wouldnt pull past that. Do any of you know what this might be. And if so the costs on a solution. My guess is the only solution to the problem is a new engine. $$$. Oh well, tell me what you think.