6.4L HEMI issues, stumped.

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Canadian Mopar

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I have a 2017 Ram 2500 with the 6.4L HEMI, just rolled over 140,000 km and while towing a trailer a few months ago I got a CEL with a cylinder misfire code on #7, when this happened there was a noticeable tapping noise in the top end, to me it sounded like #7, and the engine started to idle fairly rough. Thought that all these pointed to a cam / lifter issue. So I parked the truck and finally got around to pulling the engine here, checked and couldn't find any metal in the oil filter or really anywhere so I stripped it down and weirdly I think the lifters and cam look fine, they definitely are worn a bit but nothing that I can see that would be abnormal for this kind of mileage on the engine I think, maybe I'm wrong here. All the lifters are still rolling fine and the cam doesn't have any grooves or abnormal wear. A few of the lifters do have a noticeable groove on them, not sure what that is caused by or if it's anything that should be raising a yellow flag.
So now I'm stumped as I'm not sure if I caught this early enough that it was just on the verge of doing more major damage like some of the lifters and cams I've seen come out of these HEMIs or if there is something I'm not seeing here.

The only thing that has me worried is the exhaust valves are very white, now I've never had one of these HEMIs apart before, so not sure if that is normal with the MDS and how lean they run them or if that is something I should be looking further into.

The truck is mostly stock, it has a CAI, muffler delete, and an edge pulsar (I run on tow mode w/ MDS "disabled"). 90% of the miles since I've owned it are towing/hauling and on the highway.

If anyone could chime in and let me know if they have any ideas on what could possibly be going on here or what to check that would be greatly appreciated, thanks!

Edit: just to add, all my manifold bolts were still in tact and it didn't look like I had any leaks past the manifold gaskets so I don't think that an exhaust leak was causing the issue.
 

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Burla

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Cam looks good, wear is were expected, doesn't appear to have any needle bearings issues as there are not that type of wear scars. So your only code was P0307?
 

Ridgerunner665

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Possibly a bad lifter, just maybe not the roller part this time.... sounds like maybe the lifter lost its ability to pump up and hold the pressure.... that would cause a loud tapping, and a misfire.
 
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Canadian Mopar

Canadian Mopar

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Cam looks good, wear is were expected, doesn't appear to have any needle bearings issues as there are not that type of wear scars. So your only code was P0307?
Kind of what I figured as well, thanks. I had the misfire code and a P1521 - incorrect oil type code. I've always ran spec 0W-40 in this engine so not sure what that was all about.
 
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Canadian Mopar

Canadian Mopar

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Did you check the coil and the plug on that cylinder before tearing it down? Also you managed to 140K without having any broken exhaust manifold bolts? I wouldn’t worry about the white exhaust valves, looks like normal combustion to me.
Awesome thanks, ya the manifold bolts being in tact surprised me as well. No I didn't check coils or plugs as it sounded pretty metallic and I thought for sure it was a lifter / cam issue.
 

Burla

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Kind of what I figured as well, thanks. I had the misfire code and a P1521 - incorrect oil type code. I've always ran spec 0W-40 in this engine so not sure what that was all about.
well I do believe every single cam fault code was the p0300 range. If there is good news, when you button it up I assume with new cam and lifters, well it appears your hemi wears well, and you don't have a lubrication issue that seams to plague some hemi's. That is a mis fire code? I need to check that one.

or, maybe you don't even need a new cam, dunno.
 
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Canadian Mopar

Canadian Mopar

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well I do believe every single cam fault code was the p0300 range. If there is good news, when you button it up I assume with new cam and lifters, well it appears your hemi wears well, and you don't have a lubrication issue that seams to plague some hemi's. That is a mis fire code? I need to check that one.
Oh no, sorry that was another code that popped up at the same time as all this started, so both the P1521 and P0307 codes.
 

Burla

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So I don't see that is a mis fire code, maybe I am wrong, but how do we make it better? Let me ask you a question, when you received that code how cold was it outside?

awe ok gotcha. posted at the same time, how cold was ambient temp when this happened? that code is fr viscosity, first time we seen that.
 

Burla

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If it was cold when this happened, you see how thick that oil was, 0w40 is similar to 5w40 in this graph. So even you were using the correct oil, the pcm thought it was too thick.

OIP.jpg
 
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Canadian Mopar

Canadian Mopar

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So I don't see that is a mis fire code, maybe I am wrong, but how do we make it better? Let me ask you a question, when you received that code how cold was it outside?

awe ok gotcha. posted at the same time, how cold was ambient temp when this happened? that code is fr viscosity, first time we seen that.
It was around freezing, so not that cold, especially for up here. I had been a fair way into a road trip as well so everything should have been well up to temp. I will say as well that when my CEL light came on I was passing on the highway and had my sock in it with a trailer behind so it was workin. I remember it being really windy that day too.
 

Burla

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ok that's good, then it was a psi thing. It was reading too thick because of the load. Next question, how long did it run rough after that? Did you clear codes and codes never came back? Did it run bad until you tore down?
 

tjfdesmo

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Out of curiosity, and not throwing stones, but did you do a compression test and leak down test before yanking and tearing down the engine? It's quite a jump from a CEL to parts on a bench.
 

Burla

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Out of curiosity, and not throwing stones, but did you do a compression test and leak down test before yanking and tearing down the engine? It's quite a jump from a CEL to parts on a bench.
true, but you have to admire the stones on that dude? I do.

OP do you even have a guess at the engine temp when you tossed that code? Is there anyway it was too hot, as in over 225f engine oil?
 
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crackerjack1957

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It was around freezing, so not that cold, especially for up here. I had been a fair way into a road trip as well so everything should have been well up to temp. I will say as well that when my CEL light came on I was passing on the highway and had my sock in it with a trailer behind so it was workin. I remember it being really windy that day too.
Check for a broken valve spring or bent/worn push rod from a stuck valve/bad seat on that cylinder if you haven't already.
 
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Canadian Mopar

Canadian Mopar

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ok that's good, then it was a psi thing. It was reading too thick because of the load. Next question, how long did it run rough after that? Did you clear codes and codes never came back? Did it run bad until you tore down?
Yes I cleared the CEL after that incident, but the rough idle and noisy top end were on and off. I didn't drive it a whole bunch after that but one time I'd start it and it'd be back to normal, and the next, or sometimes 5 minutes later it'd be back, or vice vera, almost like one of the lifters was sticking. As far as engine temp, no, I can't remember specifics, but right after the CEL light came on I was sure keeping a close eye on the vitals and nothing ever ran way out of the ordinary there.
 
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Canadian Mopar

Canadian Mopar

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Check for a broken valve spring or bent/worn push rod from a stuck valve/bad seat on that cylinder if you haven't already.
I did a quick visual on the springs, push rods, and value seats and didn't see anything unusual but I'll take a closer look, thanks!
 
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Canadian Mopar

Canadian Mopar

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Out of curiosity, and not throwing stones, but did you do a compression test and leak down test before yanking and tearing down the engine? It's quite a jump from a CEL to parts on a bench.
No, I did not unfortunately, from all I had read with the cam and lifter issues on these HEMIs and the combo of rough idle, CEL, and very noisy top end I figured that was the problem.
 

crackerjack1957

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I did a quick visual on the springs, push rods, and value seats and didn't see anything unusual but I'll take a closer look, thanks!
You recall low oil pressure or was it normal?
 
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Canadian Mopar

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Hey guys thanks for the insight and guidance here, I went back and double checked some stuff today and think I may have found the problem. So on this lifter (left) it was actually stuck in the "down" position I guess you'd say, I was able to get it to partly come back up, but as you can see compared to the lifter beside it, it definitely is not all the way up. It would definitely explain what I was hearing and why it was so intermittent, as it will come back up every once in a while but is very weak compared to the rest.
What's everyone thoughts, think this could be the culprit?
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