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AFM LIFTER DISABLE

Mark Stephens

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Mark Stephens Enthusiast

Mark Stephens

Posted
Posted

Hi

I have a 2007 Yukon that only starts ticking when I am parked at idle for 5 to 10 min,,,starts then gets loud. Once I rev the engine or start driving it disappears....Had the whole top of motor redone 3 yrs ago by a dealer.....Broke now and wondering if maybe have someone shut off the afm could possibly stop it being it only happens when I am idling

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

The AFM/DoD is not active during idle, so I don't see that being the exact issue.

 

Even if you do disable it, the noise would likely still be there at idle.

 

It seems that something valve train related is not getting enough oil, then when you rev the engine it pumps oil back into the lifters/pushrods/rockers and quiets the engine back down.

 

Is oil pressure staying steady around 20-30psi hot?

 

Have you tried different oil brands or when was your last oil change?

 

What about using an engine additive or running some transmission ATF through the engine to help clean it out and see if that helps?

Sierra Dan Senior Enthusiast

Sierra Dan

Posted
Posted

Possibly a collapsed lifter.

There are full AFM delete kits out there for around $700 plus labor.

Check out this video of a lucky cheap fix for collapsed lifter....

 

 

 

swathdiver Senior Enthusiast

swathdiver

Posted
Posted
2 hours ago, Mark Stephens said:

Hi

I have a 2007 Yukon that only starts ticking when I am parked at idle for 5 to 10 min,,,starts then gets loud. Once I rev the engine or start driving it disappears....Had the whole top of motor redone 3 yrs ago by a dealer.....Broke now and wondering if maybe have someone shut off the afm could possibly stop it being it only happens when I am idling

Seems to me that you are losing oil pressure at idle for some reason.  How many miles now on your twelve year old Yukon?  A common LS oil pressure problem is the pick up tube o-ring that goes into the oil pump.  If you add two more quarts of oil to the motor and let it idle, and the oil pressure remains normal, you've identified the problem.  Don't drive the truck with the extra oil in it!  Just idle it to test or stick the nose down a steep ramp and test it.  The goal is to submerge the o-ring and pickup tube in oil.  

 

There are other causes of low oil pressure and noisy lifters.  

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