98 Sierra k1500 rod knock or lifter tick?

[Tlee94sbc350]

on cold start I get a pretty noticable ticking. what I find weird it that when I put it in drive or reverse and accelerate, the ticking picks up. but it also ticks when I apply pressure to the brakes. if I rev it past 2800rpm the tick goes away. did anyone have an idea of what this could be? going to get a stethoscope on it in the next day or 2 to pinpoint where on the driver side rear of motor it might be at

 

[Pollo Dustino]

I have a similar concern on my 1998 GMC K2500 Suburban with the 5.7. Noticeable engine tick at idle and under light load. Compared to my other vehicles with lifter tick it sounds different, a bit deeper in both tone and location. But it's rhythmic with half engine speed, so it's most likely a lifter tick noise that I'm no longer accustomed to since all my other vehicles are overhead cam engines, I haven't had a pushrod motor in my fleet in twenty years.

When I watched this video it made me more convinced it's lifter tick compared to rod knock:

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I put a cup of ATF into the oil to see if I can clean out the lifters while driving. I've noticed a slight improvement over 400 miles so far.

Since you say it's on cold start are you sure it's not an exhaust leak? Does the noise go away completely after the engine warms up?

 

[Tlee94sbc350]

it actually goes away completely once I rev it past 2800rpm. goes completely away.

 

[Tlee94sbc350]

could this be a flex plate issue? it ticks so quickly it has me wondering and thinking it isn't a lifter or rod knock. because the engine runs smooth and has good power.

 

[RichLo]

Worse in drive or reverse leads me to think Flexplate.

 

[SableSlayer]

What's your oil pressure at idle?