@opinionmechanic: Bearing Knock (Rod/Main Bearing Knock) Where it comes from: Inside the engine block — specifically from the crankshaft area. Sound: • A deep “thud” or “knock-knock-knock”, metallic but heavy. • Think of someone tapping a wrench on the block with rhythm. • Louder when you rev the engine or under load (like when accelerating). • Follows engine RPM — the faster you rev, the faster it knocks. Typical causes: • Worn out rod or main bearings. • Low oil pressure or oil starvation. • Dirty or thin oil (people who skip oil changes, I’m looking at you 😅). • Crankshaft journal damage. Symptoms beyond sound: • Oil pressure warning light may flash. • Metal shavings in oil. • Engine vibration or loss of power. • Ignoring it? That’ll end in a full-on engine rebuild. ⸻ ⛓️ 2. Timing Chain Issues Where it comes from: Front of the engine (timing cover area). Sound: • A rattle, clatter, or metallic slapping noise. • More noticeable on cold starts or idle. • Sometimes goes away when the oil pressure builds. • Doesn’t usually follow throttle the same way as bearing knock — it’s more chain speed dependent. Typical causes: • Worn chain or tensioner. • Broken chain guide. • Incorrect timing gear alignment. • Low oil pressure affecting the hydraulic tensioner. Symptoms beyond sound: • Poor starting. • Engine misfires or loss of power. • Check engine light (timing correlation codes). • If bad enough — chain can jump teeth → bent valves or no start.

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Saturday 04 October 2025 08:05:33 GMT