Active Fuel Management (AFM) is a cylinder deactivation system on some General Motors vehicles. They can be problematic so when one acts up, you look to the common causes. When that doesn’t fix it, you ask your fellow techs. SureTrack community member Ourfamilygarage had a Chevrolet Silverado in their shop that would had a ticking noise in the engine and they thought it might be related to the AFM system. They posed the question to the community, and with the help of fellow community member JimA and others, they were able to resolve the issue quickly.
The following Community Fix summarizes the interaction between members of the community that led to the solution.
Vehicle
2007 Chevrolet Silverado 1500 5.3L
Title
Engine ticking noise and foamy oil, replaced pickup tube o-ring.
Complaint
Ticking noise on drivers side of engine that increases frequency with RPM increase and does not go away once warm. With valve cover removed the oil coming up is very foamy. Oil has 3000 miles on store brand synthetic 5W-30 and Purolator upgraded filter. Also oil pressure gauge not functional.
Diagnostic Steps Performed/Parts Replaced
Scanned vehicle had oil pressure sensor code and a EVAP code. No misfire code, but cylinder 2 was missing a few times a minute. Removed driver side valve cover. Vehicle has Active Fuel Management (AFM) but doesn’t appear to have any collapsed lifters or excess clearance between pushrod, rocker and valves. Roller bearings are intact in the rocker arms. Started engine with cover off and noticed the oil is very foamy coming out the pushrods. What would cause the oil to be foamy? What could the noise be since valvetrain appears to be ok and it doesn’t go away like piston rocking noise usually does.
Best Answer from Community Member JimA
Some of these engines had problem with seal on oil pick-up tube going bad.
Cause
Replaced oil pressure sensor and ticking stopped but oil was still foamy coming up the pushrods. Dropped oil pan and found bad pickup tube o-ring.
Correction
Replaced oil pickup tube o-ring. Oil pressure is back up within spec. No more foamy oil or ticking.
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