2012 Tahoe Irregular Tapping in Motor

[Climbhigh300]

I have a light tapping or knocking sound that’s been going on for probably a couple years, minimum to moderately driven. It does not really have a steady rhythm at all times and does not change much with increase in RPMs. It’s not a very fast tap, actually kind of slow and irregular. Most times it’s fairly quiet but sometimes gets a bit more noticeable when idling, which she don’t idle the smoothest either. I can’t hear it after I start getting up to speed. I really don’t think it’s valves or lifters. Maybe a slight case of piston rattle? It does use maybe a quart of oil between 6K mile oil changes. Any ideas?

 

[blackelky]

Cracked manifiold? Maybe

 

[Geotrash]

I have a light tapping or knocking sound that’s been going on for probably a couple years, minimum to moderately driven. It does not really have a steady rhythm at all times and does not change much with increase in RPMs. It’s not a very fast tap, actually kind of slow and irregular. Most times it’s fairly quiet but sometimes gets a bit more noticeable when idling, which she don’t idle the smoothest either. I can’t hear it after I start getting up to speed. I really don’t think it’s valves or lifters. Maybe a slight case of piston rattle? It does use maybe a quart of oil between 6K mile oil changes. Any ideas?

It would help if we could hear the sound. You can record a video of the sound with your phone, upload it to YouTube with public permissions, and link it back here. We'll give it a listen and let you know what we think. Some common non-lifter culprits of intermittent tapping-like sounds: leaking exhaust manifold gaskets due to broken bolts, loose spark plug, cracked flex plate, broken starter return spring.

 

[Joseph Garcia]

^^^^^x2^^^^^

 

[Climbhigh300]

Here’s the link to the video with the engine sound. If this is t good enough I can upload another one. I greatly appreciate any help.

 

[Geotrash]

Here’s the link to the video with the engine sound. If this is t good enough I can upload another one. I greatly appreciate any help.

That's valve train, in my opinion. It's happening at 1/2 crank rotation speed. As long as it stays quiet like that I think you're fine. If it progresses into a scraping/chirping sound, then it's time to take the next steps. My educated guess is it's a lifter tray that's no longer holding the lifter as tightly as when it was new, allowing it to twist just enough for the sound to change for a few strokes and then go back to tracking straight for a few strokes, etc etc ad infinitum.

 

[Climbhigh300]

That's valve train, in my opinion. It's happening at 1/2 crank rotation speed. As long as it stays quiet like that I think you're fine. If it progresses into a scraping/chirping sound, then it's time to take the next steps. My educated guess is it's a lifter tray that's no longer holding the lifter as tightly as when it was new, allowing it to twist just enough for the sound to change for a few strokes and then go back to tracking straight for a few strokes, etc etc ad infinitum.

That’s some good info, I really appreciate it. I’ve been leaning towards valve train myself lately. I’m planning to do the DOD and VVT delete with new cams soon, so I’m hoping that will resolve the issue at the same time along with the intermittent cyl 3 misfire code.

 

[Dustin Jackson]

@Climbhigh300 Once you get far enough into the motor to swap the cam out you’ll be able to see and address any possibly causes of the problem

 

[Geotrash]

That’s some good info, I really appreciate it. I’ve been leaning towards valve train myself lately. I’m planning to do the DOD and VVT delete with new cams soon, so I’m hoping that will resolve the issue at the same time along with the intermittent cyl 3 misfire code.

Good. That will 100% resolve it for you.