← Back to AFM/DOD

November 12, 2021 — 2015 Sierra 6.2 L86 - Tappety Tap!

By slowfive0 | Nov 12, 2021 12:00 AM | 0 views
November 12, 2021
2015 Sierra 6.2 L86 - Tappety Tap!

Hello, another bent pushrod/stuck lifter customer here. Ordered your release tool and when I got the covers off, I found a bent pushrod on #7 intake as well as #4 intake valves. #7 was making the racket and the rocker was loose. I checked the lift with a dial indicator and observed no damage and same lift as #1. At that point, the lifter wasn't stuck so I was able to replace the pushrods. NOTE: I couldn't push #7 pushrod down at the pushrod so I assumed all was good. Started it back up and it's tapping away.....Tore it back down and #7 rocker is sloppy loose (#4 is not). I pulled the intake off to try the release procedure and had to stop due to the rain. Am I on the right track here? Is maybe the lifter damaged and not going to stay locked once I release it? NOTE: owned and maintained the truck since new. Now has 170,000 miles on it and has been problem free til now. Was on a trip and started hearing it tapping whenever it would go into 4 cylinder mode. I did my best to either give it a little more gas or let off so it would kick out of 4 cylinder mode to minimize any damage. I got about 200 miles and was driving along and it started missing, dash lights went off, mil light starting flashing (has P0300 in memory), etc. Towed it home and here I am. Appreciate your site and help---thank you.

8Comments
296 Views

Replies (8)

By slowfive0 | Sep 1, 2026 8:26 PM
Nov 12, 2021

When it started, you heard a clunk and it started tapping right away. Rocker was sloppy loose when I got the cover off.
By slowfive0 | Sep 1, 2026 8:26 PM
Nov 12, 2021

I think it would be safe to say that I didn't get that lifter to latch last time. Referring to how you would tap on the top of the rocker before you tightened it all the way down with a screwdriver handle, etc to make sure they were seated....? I must not have done that right. Hoping so anyways
By Crazed Performance Repair | Sep 1, 2026 8:26 PM
Nov 12, 2021
"

Ok, good deal. Though now even I'm not sure the source of said noise hopefully someone else can chime in.
By slowfive0 | Sep 1, 2026 8:26 PM
Nov 12, 2021

I used some aftermarket 5/16 .080 wall units. I took it back apart and #7 rocker arm is loose. #4 is good. New pushrods are not bent. Rocker arm shows some wear on the body where the old pushrod was banging against it. The seat looks fine. I looked at all of them with a jewelers headband magnifier.
By Crazed Performance Repair | Sep 1, 2026 8:26 PM
Nov 12, 2021
"

You might have another bent pushrod. Did you replace them with factory or something like my upgrade? You might want to also look into if your rockers are worn in a way that is allowing it to shift over a little bit.
By slowfive0 | Sep 1, 2026 8:26 PM
Nov 12, 2021

All the pushrods showed very slight wear in the middle of the pushrod. The 2 pushrods that bent were messed up. Heavily gouged up at lifter area as well as head area.
By Crazed Performance Repair | Sep 1, 2026 8:26 PM
Nov 12, 2021
"

Did the pushrod have any signs of wear against the side?
By slowfive0 | Sep 1, 2026 8:26 PM
Nov 12, 2021

I'm also trying to better understand why it was only tapping away in 4 cylinder mode but drove fine in 8 cylinder mode prior to it failing outright? Wouldn't that indicate that the lifter spring was broken or the lifter was hanging up internally? And finally, I'm concerned about the lifter rotating in the plastic bucket. When I checked the lift on #1 intake, the lifter didn't drop as it went over the nose. I would consider that normal, but #7 intake valve did follow the cam profile no problem (didn't have to physically push the pushrod/lifter/dial indicator down as it went over the nose). Worried that bucket may be excessively worn or damaged......thoughts? Am I over analyzing it......hope so lol

Members
Ryan Tucker
Follow
jsomething
jsomething
Follow
johnwillsey
johnwillsey
Follow
Tom DeWitt
Follow
Taylor Byrd
Follow
See All Members (39)
4.9 u00b7 Reviews

Post a Reply

Login to post a reply.