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Posted

Hi, new here hoping for some.expertise.

New to me 99 Sierra 5.3l has a mid RPM tick.  Not loud but it's there.

Quiet idle...only shows between 1800 and 2500 RPM.  I've heard the lifter and rod knocks and they are very pronounced ar idle.  My idle is perfectly quiet. 

Good oil pressure, no codes.  

One broken manifold bolt and I installed a bracket but made no difference. 

Doesn't seem to matter if it's cold or warm... 

I suspect an exhaust leak, but need some expert opinions on this.  

 

Any thought?

Thanks!

Dan

Posted

Exhaust leaks can certainly sound like a tick.  And you do have a broken bolt. I’m also of the opinion that if I have a leaking exhaust manifold for whatever reason, I should replace the gasket, because it may have blew out.  Then your bracket would make little difference.  I’ve listened to noises through a rod to try and diagnose rotational noise.  Perhaps it would work for a tick.

None of this is an expert opinion though.

Posted (edited)
1 hour ago, CamGTP said:

It's exhaust leak or lifter tick, hard to say without being there.

Have you heard a lifter tick that shows only at mid range rpms?  Every description I can find is pronounced ar idle...I'm trying to rule things in or out...the quiet smooth idle is a telling sign to me, but don't have enough experience with the 5.3l to say for sure.  

Edited by Dan Poelstra
Posted

Yeah it can happen. Years ago I had a 2006 Sierra with 255,000 miles. I replaced all the exhaust manifold bolts, exhaust gaskets, new y-pipe and all that because it was a problem and noise. The lifter tick was tame at idle but always had a good tick at rpm too. At that mileage I'm sure the camshaft had some wear too but I never opened the engine because it ran just fine.

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