LS3 Tapping Noise

[C6Maverick]

I'm experiencing an intermittent tapping noise coming from under the intake manifold. Also, hesitation during acceleration. Has anyone else had this issue in an LS3? I'm being told its possibly a turned lifter. Local dealership recommended replacing the engine.....WTH! Car doesn't run erratic, oil pressure hasn't changed and no decrease in gas mileage. Any suggestions or options from the field?I'm weighing my option on repair or replace of the motor. 140K miles on a 2012 GS.

 

[Hib Halverson]

On an engine with 140,000 miles, there are any number of issues which could could cause hesitation during acceleration. You'd have to post a little more detail about the hesitation before anyone here could offer a credible answer. Is it off-idle? Is it a hesitation once the engine is already at wide-open-throttle. Low rpm? High rpm?

As for the tapping noise, without listening to the engine, there are any number of problems, including a "turned" lifter which could cause an engine noise. Does the tapping change speed as you rev the engine? Or, do you hear it only at idle.

I think the dealer wanting to change the engine just because there is a possible "turned lifter" is more an attempt to sell you work rather than an attempt at good diagnosis.

The car is out of warranty, so I'd go looking for a more conclusive diagnosis before I'd spend any big money–maybe pay the dealer to pull the intake manifold and the valley cover and inspect the valve gear. If it truly is a turned lifter, there there may be other valve train components which are damaged so, if that's the diagnosis, then, yeah, at 140,000-miles, I'd either overhaul or replace the motor.