"What are the most common issues with the S14 engine in this M6?"

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The 1988 M6 never used the S14—BMW fitted it with the Motorsport-derived 3.5-litre M88/S38 inline-six (24-valve, DOHC). The most frequent headaches owners report are:

1. Timing-chain guide rails—The plastic rails get brittle and can break, taking the chain, tensioner and even pistons with them. Budget for periodic inspection and pro-active replacement.

2. Head-gasket seepage—after 80-90k miles the multi-layer steel gasket can start weeping coolant or oil; catch it early before overheating warps the alloy head.

3. Valve-lash adjustments—solid lifters need checking every 15-20k miles; tight clearances cost power and can burn valves.

4. Oil starvation on hard cornering—pan baffling is minimal; keep the sump full and use 10W-60 synthetic to protect the bearings at high rpm.

5. Distributor cap & rotor—six individual caps mean six chances for hairline cracks and misfires; carry spares on long trips.

6. Fuel-injection harness—age-hardened insulation can flake, causing erratic idle or hot-start issues.

Parts are still available but specialist labor adds up, so factor that into ownership costs. Want help finding comparable M6s or a pre-purchase inspection checklist?

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