Varying Knocking/tapping under my truck

Sketch414 · Jun 30, 2022

Put Redline in, seems much more quiet. I did the stethoscope and it's not making any noise on the top end- but doesn't sound like rod knock. Going to do metals test on next oil change. Mechanic couldn't hear it like I had in the video, thought it could be lifters or valve misadjustment. For some reason it's loud in LA county but not 70 miles south of it??? I'll put a before and after in a bit.

Burla · Jun 30, 2022

Sketch414 said:
Put Redline in, seems much more quiet. I did the stethoscope and it's not making any noise on the top end. Going to do metals test on next oil change. Mechanic couldn't hear it like I had in the video, for some reason it's loud in LA county but not 70 miles south of it??? I'll put a before and after in a bit.

That's good news, but it gets better over time which should even quiet it more. The plating effect of EP additives happens over time, and that holds up for the entire interval regardless of if the viscosity shears down. Glad it helped, join the club, literally over 100 of guys rolling around this site that were helped by this. you go 5w30 redline with 20-820 rp filter?

Ron Boggio · Jun 30, 2022

What you have described sounds a lot like the catalytic converter. Check the heatshield and confirm it fully attached. It should not move at all. In your description you say "tapping", is it possibly a tic sound? The reason this is important, you noticed a change in milage. Tic sounds usually are caused when unburnt fuel, coolant or oil or any combination of these reach the converter. The substrate in the converter will burn those off. As it burns off it makes an inconsistent tic sound. The tic noise is most often noticed on cold start and idling. It can also be caused by an exhaust leak letting air get pulled into the converter. If the unburnt fuel, coolant or oil is significant there is the potential of slowly plugging the cat. The sluggish launch could possibly be the converter is partially plugged. If you have an emission station they can run a five gas analysis to confirm. Also with the vehicle cold, slap the outside of the cat. If the honeycomb substrate inside has broken free or into pieces you will know straight away. It will sound like a baby rattle.

Sketch414 · Jun 30, 2022

Burla said:
That's good news, but it gets better over time which should even quiet it more. The plating effect of EP additives happens over time, and that holds up for the entire interval regardless of if the viscosity shears down. Glad it helped, join the club, literally over 100 of guys rolling around this site that were helped by this. you go 5w30 redline with 20-820 rp filter?

The guy who did it wasn't there when I picked it up so I'm not sure, I'm calling him back tommorow.
So with redline, the internals aren't going to get any worse damage and such? I'd would like this thing running for a long time and debating if it's worth getting my roof repainted (the seal coating stuff is toast)

Burla · Jun 30, 2022

Internals wont be worse at all, in fact it is likely to slow wear rates to close to zero in high mileage engines, especially if you had hemi tick and then it went quiet. I read back, my apologies, I should have explained 5w30 and that specific filter is the way to go, remember that for next time. There are specific reasons for that combo it is posted in a few places. That combo is the best in viscosity plus additives plus filter that outlasts oil and is high flow. You took step one, look around the forum and next time go with that combo, should even be better.

Sketch414 · Jul 7, 2022

Alright so drove a hundred miles with the redline, tapping has returned. It was better the first couple starts but I'm not sure if thats just from the environment not giving me the echo. 1/2 temp there's noise in the same tone/intensity just a different pattern, less like a tapping/impact sound though. Full temp is still smooth and quiet. Nothing heard from inside the cabin.
He didn't do a full change of redline just topped it off to try it out and that might be why. Going to do your combo next.
Went to another mechanic, he said it's more likely connecting rod bearings or piston slap as it's bottom end. And just redline until I jave the money to do a rebuild.
I crawled under to check the heatsheild and cat but I'm not actually sure where it is on these.

Youngtriggerbot · Nov 19, 2022

Check your flexplate/flywheel mines was ended up cracked in a circle by the bolts it only made the sound in park or neutral never in drive or reverse

Dodge 1500 4X4 · Nov 19, 2022

Sounds like piston slap to me, when the engine warms up the piston expands and to noise goes away, mine only does this in colder weather, I wouldn't worry about it

Burla · Nov 20, 2022

Piston Slap can happen with frequency with outside temps at 40f or lower. You need to explain exactly when it happens, cold versus hot, dry starts? etc. Piston slap is usually in the cold and goes away as engine lubricates. The good news is if you are getting piston slap if you ever do a real redline run, the correct oil is 0w30 redline or thinner.

What does top it off with redline mean? You took some oil out and put some redline back? It was low oil and you put redline in? Some deeper explanations is needed here.

Oliver Closehauf · Nov 20, 2022

The way that was going down the exhaust pipe I would do the stethoscope test on the manifolds where they bolt to the heads.

Daw14 · Nov 20, 2022

You did not try redline ,you replaced a quart maybe ? Do a complete oil and filter change ,then see what that does . One quart is not going to have much if any impact . Do not fear ,it’s just really good oil .

dork17 · Jul 28, 2023

Sketch414 said:
Started maybe a month ago, there's a light knocking/tapping sound with a weird uneven rhythm (as in some taps are louder some are softer, not evenly spaced out). It starts after the rpm drop on startup and quiets down after driving a while. It can be heard from the front tire to the back tire, coming from the underside.
I have a 2012 with the 5.7 Hemi and 122k miles. Always maintenanced on time, had the hemi tick from exhaust leak/manifold fixed and fuel injectors cleaned this year. Performance hasn't been affected by this specifically but it's been occasionally sluggish on acceleration since a while before this noise appeared. My mpg got a little worse though.
Hopefully this link works, here's a walk around: https://photos.app.goo.gl/cia8adSn3fKhR86t5

You ever figure out what this was?

Varying Knocking/tapping under my truck

Sketch414

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Burla

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Ron Boggio

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Sketch414

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Burla

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Sketch414

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Youngtriggerbot

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Dodge 1500 4X4

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Burla

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Oliver Closehauf

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Daw14

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dork17

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