DD15 Low Compression – Cylinder 6 Failure EXPLAINED

In this video, we break down a common issue on the Detroit DD15 engine — low compression on cylinder 6. The truck came in with poor performance and hard starting, and after testing, we confirmed a major compression drop on one cylinder. After inspecting the engine, we found: Excessive valve seat wear causing major compression loss Worn camshaft and damaged cam housing bores Good liners and injectors, which we reused Preventive fuel pump replacement at the customer’s request We replaced the cylinder head, camshaft, and cam housing, torqued everything to spec, and restored the engine to full operation. ✅ This is a real-world walkthrough of how low compression isn’t always solved with a valve set. We show what to look for, what to inspect, and how to fix it right. 📍 Need expert diesel diagnostics and repair? TAT Express Inc. – Keeping You Rolling 📍 4140 Langdon Rd, Dallas, TX 75241 📞 Call: 972-225-3017 Subscribe for more heavy-duty repair breakdowns and real shop repairs!dd15 low compression cylinder 6 dd15 detroit dd15 engine semi truck low compression cylinder head replacement dd15 dd15 camshaft failure diesel engine repair tat express truck repair dallas semi truck diagnostics