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Rattle sound when starting

I am posting this for a friend - she has an older (think it was a 2010) Camry. Most of the time, from a cold engine start in the morning, when she starts the motor she hears a rattle/clank noise for a few seconds that stops. It will repeat itself sometimes during the day when it is started again, but not always. She has tried using an oil treatment for a possible lifter noise, she has replaced the starter and noted the car starts better, but the rattle/clank noise continues on cold starts. She has heard/researched on the net that this is possibly a cam gear that is bent/going bad. Anyone have any ideas on this?

I had a similar situation, it ended up being a bad bearing in the tensioner, Proper diagnosis for a proper repair.

It almost sounds like a rod bearing knock that goes away when the oil pressure hits.

Hopefully she has checked the motor oil level. Without hearing the noise it’s near impossible to be definitive but a rattle/clank that goes away right after startup often points to a rod bearing noise.

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Could also be a loose heat shield in the exhaust system somewhere. Once it warms up, the metal expands and rattle stops.

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I know she has checked the oil level and has recently had it changed.

Are you referring to the timing tensioner or the serpentine tensioner?

I forget about the heat shield, somewhere to check.

I was referencing the serpentine belt tensioner.

Knocking noise from the variable valve timing gear during start-up is a common problem on the 4 cylinder engine. The engine oil drains from the lobes inside the gear creating a void and results in a knocking noise during start-up.

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