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T-belt on Sienna 2004 was broken. How do I do re-timing for my car both cam-and-crankshafts before installing the t-belt? Thanks

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    Answer will probably vary from engine to engine. Add more detail about your car and don't use abbreviations - they make searching hard. In most cases there are special marks that line up in a certain way to set everything at TDC (Top Dead Center).
    – JPhi1618
    Oct 13, 2015 at 17:15

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Before installing the timing belt, I'd worry about engine damage

The 2004 Sienna came with two engines:

  • a 3.3 L V6 (code 3MZ-FE), which comes with a timing belt
  • a 3.5 L V6 (code 3GR-FE), which utilizes a timing chain

Both of these engines are interference engines, so the pistons and valves will occupy the same physical space at different times while the engine is running. If the timing is out, the valves and pistons can come into contact with one another.

Since the question refers to a timing belt, I'm assuming the OP owns the former, in which case there is a bigger issue to worry about.

If a timing belt snaps on an interference engine while it is running then you can expect internal damage to the valves and pistons.

Do not attempt to turn the engine over, even if cranked by hand. I'd imagine the least invasive approach to inspect the piston surfaces would be to use a borescope. Unfortunately things do not look so optimistic for your engine.

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