Weird noise- pretty sure not wrist pins

Over the last couple months I have noticed an odd knock from my 6.4. Pretty sure it's not wrist pin related because even though mine falls into the correct build date range I never hear it on start up nor when I am driving and at 23000kms I suspect it should have reared it's head by now. It's intermittent but I can reliably reproduce it with the right circumstances.

Basically if I have been driving and everything is warm and I then park it for an hour or two, upon next start the engine (once it idles down) with produce a very audible "knock knock knock" and it keeps pace with the idle. If I touch the gas, it goes away and does not come back unless I repeat these steps. If I leave it idle for a few minutes again- it goes away. I have kept the windows rolled down periodically to listen for it during driving but I haven't caught it... yet although I was suspicious I maybe heard it on the highway last night, but I may just have ears that are now looking for it and may have been mistaken.

Any thoughts? I am gravitating to an oiling issue/ design byproduct. I am going to contact my dealership (for all the good it's going to do because everything is always "normal") to get it looked at, but thought I'd run it by you guys too.

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Maybe a lifter is bleeding down?

Hopefully it's nothing serious.

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I am hoping so too, but I guess even the worst case scenario has a happy ending (new mill). Just seems odd that it's just recently started after all this time.

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^ I'd say lifter.. My truck now has 27k miles on it .. At like 9k miles.. I parked on an incline.. Went and had dinner .. Came out started the truck am I thought it was about to drop a lifter.. It was loud.. Applied a little throttle and it was gone. It really hasn't done it since.

Mines pretty consistent, I'll pop it in I guess to get told it's normal and they all do that. Sure miss the two experienced guys they used to have before they burned them out :/

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Wonder if maybe I should change the filter to see if it's the issue? It's the correct mopar filter but perhaps it is allowing that drain back- maybe just faulty?

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What kind of oil and filter do you run? I used to get all kinds of start up noise until I switched to Amsoil.

I'll throw this in here because it may be related. If I move my truck out of my driveway, or a short distance at work on the job. The next time I crank it (after around an hour) I get a cloud of dark smoke. Almost like bad valve seals or something.

Using the mopar filter and PP 0W-40 as perscribed.

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I used to get what you're talking about. If I shut off the truck on a slight incline and then started it back up and hour later it sounded like the lifters were pumping up. When I changed to Amsoil oil and filter it completely went away. Several other people have reported the same experience and it may be worth a try for you.

Maybe I'll give it a shot. Amsoil is rare stuff around here. I like buying from the dealer though, I do my own maintenance but they have always treated me good so I like to buy what I can from them. Their service department is just a little lacking in experience at the moment so I am always leary about it.

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Lifters tick they don't knock and anything worn enough to create a knock isn't likely to be intermittant and will get worse the hotter it gets.
An engine that has a cylinder that is not just firing properly on start-up or an older engine with a cylinder not up to ***** can sound like a dull knock(all cylinders not firing evenly).You might have a leaky or partially plugged injector that clears that cylinder after you rev it up.I'd be looking for a weak cylinder on start-up.

Just picked it up. Original response was "likely normal", "they all make that noise", then I spoke directly to service manager, showed him the vid and he said "that ain't right" so they kept it this afternoon.

Did say to monitor it and if it's gotten worse to come back. They have a paper trail now. They said they couldn't get it to knock once and not for lack of trying.

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smurfs_of_war said:

Just picked it up from the dealer. "Normal", "They all make that noise".

Did say to monitor it and if it's gotten worse to come back. They have a paper trail now. They said they couldn't get it to knock once and not for lack of trying.

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Aka, "no code. We don't know what the **** it could be." Lol.

I was talking the other day with a kid going to a technical college to become a mechanic. I told him with all the new crap on the these vehicles I wouldn't want to work on them. He said it's really easy because everything is monitored and the computer tells them exactly what is wrong. I replied, when it throws a code. What about when it doesnt? Well, yeah that sucks.

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Mine did the same thing once in a blue moon before I changed my oil (last oil was Mobil 1). After I changed my oil to Castrol Edge(About three weeks ago) i hear it more often. Almost every other morning, especially when its cold out side. By the time the truck warms up, it's gone. I'm ruling out wrist pins because from what i've heard, the wrist pins knock pretty loud and are always there. Mines just faint and goes away.

I guess on the plus side the shop has an old hat tech now who is really good. Pretty happy to see his level of experience on the floor now. Service manager is a pretty awesome **** too so I know they won't leave me hanging. I really can't say anything bad about the dealership- they've always treated me well, I just get nervous with all the new faces I see in the shop all the time. Most of them don't even look old enough to shave yet!

Anyway, if I have any updates I'll post back. For now it's status quo.

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Well, third visit to the dealership this morning and that's that. Apparently this is normal?

Well, ****.

Have you looked over your exhaust bolts and made sure one or two heads are not missing?

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drittal said:

Have you looked over your exhaust bolts and made sure one or two heads are not missing?

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Sure did. All looks tight and proper.

How much warranty do you have left?

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