03/06/2026
Not Every Timing Chain Job Has a Happy Ending...
This BMW X5 came into the workshop for a preventative timing chain replacement on its N57 engine.
As part of our engine-out timing chain procedure, we began preparing to remove the torque converter bolts, which requires turning the engine over by hand. Straight away, something didn't feel right. The engine was noticeably harder to turn than we would normally expect.
Rather than carrying on and hoping for the best, we stopped and investigated further.
The first thing we checked was the oil filter, and that immediately confirmed our suspicions. The filter was full of metallic debris — it genuinely looked like someone had poured a bag of glitter into it.
At this point, we contacted the customer and explained our findings. With their approval, we removed the engine for further inspection.
Unfortunately, the news got worse.
Upon strip-down, we discovered that one of the centre main bearings had spun, causing significant damage to both the engine block and crankshaft.
The damage was severe enough that the engine would require:
❌ Crankshaft replacement or specialist repair
❌ Engine block machining and line boring back to factory specification
❌ Complete engine rebuild
The alternative would have been fitting a replacement engine, but with used N57 engines commanding strong money and their history often being unknown, it wasn't a straightforward option either.
After discussing all available options and costs, the customer made the difficult decision not to proceed with the repair, as the vehicle was no longer economically viable to repair.
This is a perfect example of why proper diagnosis is so important. It would have been easy to continue with the timing chain replacement and only discover the underlying engine failure later, but that's not how we operate.
Sometimes the fault isn't the one you came in for.
📍 Costigan Motorworks
📞 07539 770525
BMW & MINI Timing Chain Specialists
Engine Diagnosis • Engine Rebuilds • Timing Chains • Servicing & Repairs
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