Seller says engine has valve problems on right side. Buy or don't buy?

[The Radium King]

well, he doesn't know what is wrong, but he knows what bank it is. so, i am *assuming* that he got a cel specific to the bank. it is still running, so not a catastrophic failure (yet). a failing ims will do this - wobble enough that a chain skips a tooth. the other way you might see a timing failure is a failed actuator on the variocam. this is assuming no-one has already been in the engine messing with things. should be able to diagnose quite quickly with a durametric or at a dealer. ims is the cheaper of the two fixes, but both are in and around the cost of a replacement engine, so the car should be valued as a roller. at $3k for a 2002 S i think you are about right.