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Discussion Starter #1 (Edited)
I have a 2006 Jeep Commander 5.7L Hemi, and on my last oil change, I had the truck on the lift checking for leaks and I could hear a light tapping sound coming from the engine.... Vehicle only has 59,000 miles on it. Could this be my worse fear,,,, a rod knock? or something else? Seems it only does it at a low idle and doesn’t matter if it’s hot or cold. If I rev it up a bit or drive it under load you can not hear it. it's as if it goes away. But resting at idle you can hear it.

Thanks!!
 

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I don't think any of the Hemi's on the forum have ever had a rod knock.....with the exception of those that got the intake under water.

In general, a rod knock due to excessive bearing clearance will be almost imperceptable at cold idle......a bit louder at operating temperature, due to oil thinning, and increase in volume as RPM's rise.

At idle, under the vehicle, any normal engine noises will amplify due to the body metal around the block, oil pans can amplify normal engine sounds as well.

Anyways, I doubt if you have any cause for concern.

Rob
 

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I think that is the infamous HEMI "tick" you are hearing.
 

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Oh really..The HEMI's have a infamous "Tick" what is the cause of it?
Thanks!!
I don't know what causes it but some say it is the injectors. If you google hemi tick you will find some discussions about it,. Also, if you put hemi tick in the search on youtube you will get some videos about it.
 

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The Evap/Purge system has a solenoid purge valve, that could be the cause.

The Injectors like suggested.

Don't rule out valvetrain noise, the Hemi's have a pretty tortured valvetrain, the 3rd Gen Hemi's improved it by moving the CAM much higher up in the block, the earlier Hemi's breaking valvetrain parts was very common. Don't really know, just offering some suggestions. Valvetrain noise would change in frequency with the engine rpm, injectors should also, purge solenoid valve would NOT.
 

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What oil filter was installed during the last oil change. The Orange FRAM filters should be avoided like the plague, they use cardboard endcaps on the filter cartridge. Yes, in most cases the poly impregnated cardboard lasts and does NOT come apart, but, the anti-drainback valve seals against the cardboard end caps, and cardboard seals very poorly. More than few engine have suffered excessive wear in the valvetrain from dry start-ups from using those filters.

BTW, rod knock can be caused by a spun bearing, but for most engines that only happens after a serous oil problems, like no oil at all. A spun bearing would knock at idle, I think its far more likely your problem is something different that. It may be the normal hemi tic.
 
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