2004 Toyota Sienna timing belt

  • 3.3L
  • V6
  • FWD
  • 220,000 MILES
Do I need to clock the crank and cams if belt is not broken when installing a new belt. Do I line up crank mark on 2 revolutions or 1
Do you
have the same problem?
Saturday, May 9th, 2015 AT 8:08 AM

1 Reply

You have the luxury of knowing what to line up since the belt isn't broken, but there's a couple of things to consider. If you don't have a service manual with the belt routing diagram, turn the crankshaft in the normal direction by hand until the timing mark is lined up with its mark, then look for the marks at the top of the two camshaft sprockets. That way you'll know what you're looking for when lining up the new belt. Be aware that due to valve spring pressure and some open valves, the camshafts are going to rotate when you release tension from the belt, so expect the have to turn them to line the timing marks up.

Also be aware this is an interference engine. Never force any sprocket to get it to line up, and when the new belt is on and under tension, rotate the engine in the normal direction two complete revolutions, by hand, then double-check that everything is in time.

As an alternative, again, since everything is in time right now, I prefer to make sure the crankshaft sprocket is away from top dead center, then I make my own timing marks with a yellow marking pen. This way there are no pistons at top dead center and no way a valve can be bent while I'm putting the belt on. Those yellow marks are a lot easier to see too. The camshaft sprockets will want to turn a little when you put the belt under tension. If the marks are no longer in time, you simply start over or jump the belt a few teeth on the sprocket, but no valve will have been bent.

Once you have the belt on and under tension, rotate the crankshaft in the normal direction, two revolutions, by hand, then recheck the timing marks. If you feel sudden resistance, back up to where you can check the timing marks again.
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Sunday, May 10th, 2015 AT 6:50 PM

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