2011 Scion Tc with about 89,000 miles on it and the check engine light just went on. But 4 start ups before that light went on it started making this noise that sound like a piece of metal rotating but it has a rhythm. I am not sure what it could be but any guesses would help.

SOURCE: 1998 Jeep Cherokee Classic;165,000 miles.

Did you know Jeep did a recall and paid for replacement of catalytic converters on 1996 models (don't know about any others) - they reimbursed me for work done, up to a point - hope this helps!

SOURCE: Starting noise

http://www.2carpros.com/first_things/clicking_sound_while_driving.htm

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SOURCE: How do I reset the check engine light for a 2006 scion tc?

YOU CAN GO TO ANY ADVANDED AUTO PARTS AND THEY CAN HOOK UP A OBD2 SCANNER, WE THEY DO ASK THEM TO RESET THE LIGHT FOR YOU.. THIS IS A FREE SERVICE TO THE PUBLIC..GOOD LUCK KEITH..

Steve Allison

• 5569 Answers
• Posted on Oct 24, 2009

SOURCE: my scion xb will not start up. when i try to start

Yes, it could be. If it is the original, it is 5 years old.
Before I bought a new one though, I would remove the negative battery cable, then clean both battery terminals and the clamp that goes on them. With the battery negative still disconnected, you should trace both cables to their terminus, remove those and clean them too.
If that doesn't help, you can have your battery checked at any chain auto parts store. Their tester will tell you quickly if the battery will accept a charge and function as it should.
BTW: If you have a password protected stereo or alarm system, you will need that to get them working again.

SOURCE: Engine makes a knocking noise when I start it.

The reason for replacing a crankshaft 99% of the time is due to a bearing failure. Your crankshaft is the first item to receive oil from the pump...regardless of routing after that, everything else is next in line.When a bearing fails, it generates debris that travels through the entire system before returning to the filter. Therefore, every oil passage still can contain debris that can damage other bearings such as the ones for the camshaft. Knowing this, I cringe when I'm told that someone replaced a crank and bearings without totally removing the block, tearing it down to bare bones and boiling it out to remove any residue. Unless yor are very lucky you will end up with the condition you now have. If you continue to use it, more than likely the engine will again fail.
Your engine has seven hundred thousand miles on it?
(or you put too many 0's?)
In any case, I seriously doubt if the noise you hear is from carbon. I can't see and hear your engine, but I'd definitely get a second opinion from a "hands on" tech. Before going any further with that particular shop.