No site tells you which engine to buy and which to avoid – until now. What Breaks is the largest used car weakness database: 28,000+ issues across 850+ models and 4,500+ engines, curated from real forums and service bulletins. Every engine gets a traffic light rating. Browse by make, model, engine – see what breaks, what it costs, and better alternatives. US coverage growing daily. Chrome Extension for Autotrader.com coming soon.