My brother's 1990 740t seems to have what sounds like piston slap- very noisy. It doesn't get quieter as the engine warms- if anything it gets louder. He's isolated it to #2 cylinder by pulling the #2 plug wire. The slap ceased. It runs fine and has good power. It has passed emission testing and doesn't use oil. He's been driving it for over a year like that- since he bought it and it was like that for who knows how long before that. That said, it's the loudest piston slap I've heard. We've been told that it is the cylinder wall that wears and it may wear to the extent that it can not be bored. Is this the case? He's thinking of doing an investigative teardown. What's the remedy for this problem? Does it sound like I'm describing slap or could it be something else? Can cylinder liners be changed if they are worn beyond limits? If a rebuild is nescessary, what kind of a hit is he looking at in the cah dept.? All advise will be welcomed and appreciated. Thanks.

Peter Mac
1991 745SE 153k miles