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Hey everyone. Bought a 2012 Sequoia w/138K miles on it last October with every maint record. It has been flawless and continues to run and drive flawlessly. I noticed a knocking while leaving a stoplight today and decided to check under the hood to see if it happens at idle. Sure enough, it does intermittently. I took a video of it and you can plainly hear the knocking every so often for about a second or two and then it stops. Got any ideas? No check engine lights, no leaks, engine oil and filter is about a month old/still full and no loss of power.

 

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Wanted to add it only does this when at operating temp. When cold started, there is no ticking at all. Just sounds like a sewing machine (normal injector and valvetrain sound). I tapped around the area to see if something was expanding or becoming loose as it warms but nothing reachable. The sound reminds me of the purge valve going out on the 3.0-3.6L GM engine.
 

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Pretty hard to tell what that is. Sounds like a loose rocker arm on an old Chevy v8. Do yo have a mechanic's stethoscope? They are not expensive from Harbor Freight. That would help you narrow it down. But, whatever it is, it doesn't sound serious to me.
 

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Pretty hard to tell what that is. Sounds like a loose rocker arm on an old Chevy v8. Do yo have a mechanic's stethoscope? They are not expensive from Harbor Freight. That would help you narrow it down. But, whatever it is, it doesn't sound serious to me.
I did at one time but darned if I can find it at the moment. I ordered one and I'll post what I find and do another video. Doesn't sound serious to me either and the fact that it only shows up when at full operating temp and then cycles, makes me lean toward a solenoid/valve of some kind.
 

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I'm thinking it could be a fuel injector possibly going bad? Using a stethoscope will determine if the sound is coming from that also. If it is I would pull all eight of them out and have them professionally cleaned and tested. I did this on my 2001 Sequoia with 200k miles and was amazed how clogged they were when the flow rates were tested.
 

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My 2007 Tundra 5.7 started making that noise at around 95K. It only happens when it warms up and is intermittent. The loudness varies also. I used a stethoscope and it seems to be coming from under the valve cover. I'm the only owner and change the oil every 5K. Plenty of oil and oil is clean. I took it to my mechanic and of course it wouldn't make any noise. I've read many posts of this noise coming from this engine. It all seems normal for this engine. God I hope so.
 

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Hey everyone,

Looks like the #8 injector either has trash in it or is pooping out. The rest sound like sewing machines but #8 sounds like a sewing machine that stops every so often and then begins again much louder and then quiets down, stops, and begins the same pattern. Now the question is to replace it or replace them all or perhaps another plan? I do plan to get a flow rate check next oil change at the Toyota dealership (the one I trust).
 

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To remove the one injector the other three can be removed since they are all connected on the same fuel rail. The fuel rail needs to be removed in order to remove the injector. I would recommend removing all eight and have them checked. I removed all of mine and sent them to a fuel injection shop and they bench tested all eight and found out one was dead and all the others needed cleaning to bring them back to factory flow rate specs. Made a huge difference in my engine performance after I reinstalled them.
 

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To remove the one injector the other three can be removed since they are all connected on the same fuel rail. The fuel rail needs to be removed in order to remove the injector. I would recommend removing all eight and have them checked. I removed all of mine and sent them to a fuel injection shop and they bench tested all eight and found out one was dead and all the others needed cleaning to bring them back to factory flow rate specs. Made a huge difference in my engine performance after I reinstalled them.
Thanks for the advice. I believe I have to remove the intake manifold in order to get the fuel rails off? Looks that way to me but I could be wrong.
 

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Looks pretty easy actually. The intake manifold doesn't need to be removed. Here's a video on the process:
 
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