Occasional light lifter tick starting

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L8T BURB

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This seems VERY similar to my experience before the lifter on cylinder 4 of my 186k mile 5.3 decided to leave the chat! Oddly enough, I also used MMO in an attempt to possibly clear anything that may be blocking proper oil passage. In my situation, the MMO seemed to actually speed up the lifter failure which led to the lifter in cylinder 4 completely collapsing. I would say you're on very borrowed time here, and regardless of repairing now or later, I believe a FULL DOD delete is in order.
 
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dkad260

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if the pintle valve isn't sealing right it would lead to inconsistent taps accordingly. That's why I think it's a mechanical problem with the lifter.
Yeah, with all the lifters I've heard in my days, I don't like how this has that very light tick than a tap. I can rev it up all day long to make it quiet, but that lash is still there.

I'm not betting the farm on chemicals, but ATM it's better than pulling a head.

I really don't need this right now..lol. sigh.
 
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dkad260

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I believe a FULL DOD delete is in order
If this was a pre-2010.5 I would be all in, but there seems to be a revision after that and honestly the system works real good....that being said, I have my current issue, but I wasn't the original owner. If I was the inside would be almost spotless.

Fingers crossed on this one, next to worst case I will be pulling a head.
 

L8T BURB

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If this was a pre-2010.5 I would be all in, but there seems to be a revision after that and honestly the system works real good....that being said, I have my current issue, but I wasn't the original owner. If I was the inside would be almost spotless.

Fingers crossed on this one, next to worst case I will be pulling a head.
Hopefully you come out good on this one. FYI, my failure was on a 2015 Suburban.
 
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dkad260

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Update on this....

I used a stethoscope and it seems the loudest tap is around cylinder #6, so I pulled the valve cover to start getting into this.

Valvetrain looks real good as far as cleanliness, nothing looked out of place.

Screenshot_20231028-161802_Gallery.jpg

I wiggled all the rockers after I rotated them off the heel of the cam, all had normal back and forth but some have a little up and down.

I pulled #6 intake and the pushrod bore looked clean and the lifter looked ok from a visual perspective.

I then pulled #6 exhaust and there was quite a bit of up and down movement in the trunion....probably at least .030".

The #6 exhaust lifter bore was clean and the top of the lifter looked good, sorry, the video when on top the lifter isn't as clear as my phone display, but nothing out of place and naturally this tells me nothing of what may be going on inside the lifter. I shot some B12 in there to soak just in case after the fact.



This is the up and down movement on the #6 exhaust trunion....this IME, should not be like this. The intake moves up and down a little, but not like this.



Luckily there's a dealer near me, open late and has one exhaust rocker on the shelf. I'm going to get it and see if this hopefully changes things.

@Geotrash yeah, definitely looking like a hard part issue.
 
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Geotrash

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Update on this....

I used a stethoscope and it seems the loudest tap is around cylinder #6, so I pulled the valve cover to start getting into this.

Valvetrain looks real good as far as cleanliness, nothing looked out of place.

View attachment 412738

I wiggled all the rockers after I rotated them off the heel of the cam, all had normal back and forth but some have a little up and down.

I pulled #6 intake and the pushrod bore looked clean and the lifter looked ok from a visual perspective.

I then pulled #6 exhaust and there was quite a bit of up and down movement in the trunion....probably at least .030".

The #6 exhaust lifter bore was clean and the top of the lifter looked good, sorry, the video when on top the lifter isn't as clear as my phone display, but nothing out of place and naturally this tells me nothing of what may be going on inside the lifter. I shot some B12 in there to soak just in case after the fact.



This is the up and down movement on the #6 exhaust trunion....this IME, should not be like this. The intake moves up and down a little, but not like this.



Luckily there's a dealer near me, open late and has one exhaust rocker on the shelf. I'm going to get it and see if this hopefully changes things.

@Geotrash yeah, definitely looking like a hard part issue.
Gooooood catch!! That valvetrain is the cleanest I’ve seen so it’s definitely been maintained. But I agree that trunnion has too much play and that would also explain the lifter lash noise.
 
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dkad260

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I have some good news and some not yet good news.

The not yet good news is I still have a very light tick.

The good news, I suppose, is the tick is on #8 and not an AFM cylinder...#6.

What I did was replace the sloppy #6 exhaust rocker and I checked cyl #4 and that seemed ok, not as bad as #6.

Before I replaced the valve cover, I pulled the #8 exhaust rocker and that one is worse than #6 exhaust. I still ended up replacing the #6 exhaust rocker since that was where the noise was concentrated using the stethoscope.

When I started the engine it took 5 min for the tick to start, but overall the valvetrain was slightly quieter and now the ticking noise is very pronounced on cyl #8. Since #6 is quiet now it's very easy to isolate the location.

I will likely replace all the rockers eventually, but the next step is to replace both rockers on #8 and probably the intake rocker on #6.

At least it appears I'm now dealing with a non-AFM cylinder so fingers crossed there's no compromised AFM lifters and another new rocker will fix this.

I was surprised to see the new rocker has a slight movement up and down in the trunion, but nothing like the old one. You would think there would be near zero movement up and down or radially.
 

Dustin Jackson

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@dkad260 At that point I would have gone all the way in and done a proper inspection of the lifters and cams. LS engines have always been prone to lifter failures even before the AFM system was introduced so you could have a pitted lifter elsewhere but you wouldn't know unless you pulled the heads.

When I had a lifter failure there was a loud rattle at idle but once I tore into the motor everything looked perfect and wasn't able to find any damage until I actually got the lifters out.
 
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dkad260

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At that point I would have gone all the way in and done a proper inspection of the lifters and cams

I agree and I'm all for getting inside and seeing exactly what's going on. However we are talking about a vast difference in labor and downtime, and this is currently my daily driver.

I'm surprised the OE rockers have any up and down travel, but safe to assume it's designed that way for some reason.

I can see how problems could arise when that clearance opens up and I want to replace the other rockers on cyl 8 before I start pulling heads. Only took maybe 15 min to pull the valve cover so not a huge undertaking in the least.

The #6 exhaust rocker in the video has a good amount of radial play, but #8 had more. Rockers will be here this week and will at least get those changed out. For $12 each it's worth a try.
 

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