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I need to know if a 2005 BMW 745 LI bends the valves when it jumps time. I haven't done anything yet. I'm trying to see if I have to do the heads because it jumped time.

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  • I'm skeptical that any engine can jump a chain link or two on a timing chain. If it were a timing belt I could buy that it happened, but a timing chain? I'm not sold on it – Zaid Nov 5 '17 at 2:28
  • @Zaid A broken chain guide could do it. Mostly it's just the chain stretching though. – Ben Nov 5 '17 at 19:16
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Generally speaking, it depends how much the chain skipped. Some engines have more tolerance than others. Reset the timing chain to the proper time and it should be safe to run a compression test.

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  • Agreed. It is good to know that these engines are interference motors. If they skip time, it may not cause catastrophic consequences if it's a minor skip in time and if the engine hasn't ran much after the jump (or is forced to continue going, like through compression braking). I think your approach is a good one as by resetting the timing you're not going to cause yourself any more damage than what might have occurred in the first place. – Pᴀᴜʟsᴛᴇʀ2 Nov 5 '17 at 0:54

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