#7 Cylinder Misfire help.
 

Hey guys need some help with my 2012 5.7l Hemi Dodge Ram 2500. Truck has 250,000K on it with no rust yet. Any way last week had a diagnostic code #7 cylinder misfire. Drove it for a week and took it in to my local mechanic. He switched the coil pack and #7 still misfired. He changed out the plugs with new ones and the same thing.He now thinks it could be the cam that needs to be replaced. Anyway he suggested I take it to the dealer to confirm and if it is the cam to have them do the work as he is not set up to be able to take the cab off and tie the bay up for that amount of time.
So if it is a cam I could be looking at $5000.00+ for repair.
Would you consider putting in a new or rebuilt engine ? and how much more would that cost?
Trying to find a good used truck of the same year is $18k++ which I don't have.
Your thoughts would be greatly appreciated.
Cheers.

Ez to find if need a cam , pull valve cover and watch lifters the one that moves the least is bad cam lobe , put in rebuilt engine, all that metal went through the rest of bearings, rebuild you're looking at about $11000 all in

You may have a broken valve spring.

Take a stethoscope and listen to your injectors then compare the sounds. Ran into this many times on different vehicles.

Codes read misfire which is correct and I've changed plugs with the same issue.
Check the injectors with ohm meter and all read the same, Last resort was the stethoscope and there was a big difference in sound.

Do a compression test before anything else then pull valve cover. I’ve seen same year truck have a burnt valve that just requires the head to come off and a little valve work but my shop is set up to do head work

Compression (and timing). Spark. Fuel:air mix. You need all of them.

Your local should be able to point you to which element you're missing.

Like the others have mentioned, there is a long list of diagnostics to run before even considering engine replacement. You're going to be into a replacement engine for a good chunk over $5000. Probably north of $10k in any reputable shop. I'd exhaust all other options first.

Spark - air - fuel

Seems that your mechanic has already ruled out spark as a cause - that being said, did they actually verify that you're getting power to the coil pack, and therefore the spark plugs? Sounds to me like he took the "parts cannon" approach thus far without any diagnostics... Could be as simple as a broken wire to the coil... for which Chrysler is known, or as catastrophic as an oil starved valve train, for which Chrysler is also known. Valvetrain is fixable if it didn't throw shrapnel into all other parts of the engine.

#7 misfire is famously common on the hemi. Cam lobe is flat. For what a full rebuild is worth I would try and change it myself and see what life I would get out of it after. Not much to lose compared to the cost of a rebuild and replacement.

I have a 2011 with 220k and am now at the not of but when stage. My dad had to do both sides on his 14 with only 150k on it. The hemi is a junk motor in my opinion. Great power, decent fuel economy, but longevity isn’t there. I’m running mine until the engine goes, then it goes to the highest bidder for scrap, and never again touching a dodge that doesn’t have a 12 or 24valve Cummins in it.

Grab a 6.0L or 5.3L and Ls swap it lol if you do keep it. 5.7 hemi.. Great engine.. bad design. UTG has a good break down on the “why”. They eat Cams. Just Sucks.
https://m.youtube.com/watch?v=dI93-Zdx_nY
https://m.youtube.com/watch?v=iTL8QEU2NwE
Hope it’s something simple but knowing the “hemi tic”, it most likely isn’t.

A common hemi issue that's usually caused by a worn lobe(s) on the cam. It isn't terribly difficult to change, just lots of stuff to remove to get to it.

Xcqrbn
 

There are brand new short blocks for sale on Kijiji for around $5k. As others said, all the metal from the lobe has gone through the motor, I personally would not change out just the cam.

I swapped my engine out last spring in my 2012, and have 40,000 km on the replacement, No issues. At least I can get an engine, unlike the 5.4l ford I had…

This is a common hemi issue, and I’d bet you a beer your cam is flat. I shrug when I see people spending big$$$ ( at shops recommendation) on diagnosing and maintenance items like plugs, when the shop knows the issue. No sense in throwing good money after bad, imo

Check your injectors. If that’s not it, you’re pulling the head. Maybe you get lucky and it’s a valve spring, but if you were using “eco” mode then it’s probably eaten a cam. MDS doesn’t work. Stupid obummer EPA design. All that metal has chewed up a lot of your engine life.

You can swap a hellcat (non-MDS) cam and lifters and tune for a little more money to permanently fix the issue, but probably not worth it at this age.

At 250k you need to have a good hard look at what you have or haven’t done. Exhaust manifold, brakes, front end, water pump, thermostat, stupid azz clutch fan, stupid azz MDS solenoids…those all are known wear points on our trucks (I have a 2011). Plus all the regular belt/hose/fluid stuff. If those things are yet to be done, you’re in for a lot of maintenance costs especially if you’re having someone else do the work.

10 years old or 300k, that’s about what you get. After that point you are into diminishing returns.

Doesn't the 2500 not have mds?

Thanks for all the replies guys. Unfortunately I know nothing about engines and have no place to work inside along with minimal tools, so I am pretty much stuck depending on someone to not rip me off. I already spent a good chunk of change with all the diagnostics that has got me nowhere.
I will make a list of the things you guys suggest I check and make sure the dealer has a look at them first.
I can't think of anything else I can do.

Check you dipstick. Any glitter on it?

Don't feed me straight lines like that! :lol:

ARG

You’re right. It was the 2500 6.4 that did. My mistake.

Which rear pocket is your handkerchief in? :)

I wouldn't go any further on diag if you're going to do a used/rebuilt engine. Chances are your cam is wiped out. As others have side if it's gone on long enough a lot of that lobe material will have cycled through the engine. At 250k, I would at the very least be doing a lower then 200k engine from a wrecker and invest some money into the cams and timing chain before you swap it. As well as any other preventive maintenance items while it is on the engine stand. Rear main, crank sensor, plugs etc. Thankfully these are relatively easy engines to swap. The main thing on these trucks are oil changes. Every 5k no matter if you run synthetic or regular.

^^^^^^^^^^2X^^^^^^^^^^^^

And don’t let those hemi’s idle for long periods of time.

This is true. Top end will always want more oil at idle then they get.

Well, I bought this truck used last year as my previous one burned down.So I bought it with the insurance money. I have had absolutely no problems with it other than brakes. Runs smoothly and really good fuel economy. Yes, it does idle a lot due to the work I do especially in the winter.
The code has been on for a little over a week and a half before I was able to get it looked at.
I will check the oil in the morning for shavings.
Thanks

I had the same issue on my 2014, but different cylinder.

just like you, did the pack, plugs and then compression test, and it failed.

My mechanic tore the engine down expecting to do cam and lifters, turned out it was a sticking intake valve.

saved me a couple grand in the end.

if you want his contact info (he is a mobile mechanic in Edmonton) send me a PM.

I'm doing a leak down test before I pull the engine apart.

Well, contacted dealer and they want $10,800.00 for a remanufactured engine and it has to come from the U.S. Service dept wants $5,000.00 to install.thats $16,grand for a new motor. I am having a heart attack right now.
I really don't know what to do at this point.

I put a remanufactured motor in my Ram 1500 in may 2022 which motor cost me 5600$ after I sent my core in. Did the install myself but a reman motor for that price was easily swallowed with three year unlimited mile warranty.

Had to swap over all my tin from my existing motor but all went well.

Allan and sons auto recyclers in Alberta have new not reman hemis for 7800$ plus gst. Look it up on Kijiji. They are in Irricana

Nope they don't

Allan and sons auto recyclers in Alberta have new not reman hemis for 7800$ plus gst. Look it up on Kijiji. They are in Irricana[/QUOTE]
I gave them a call and they will charge $200.00 to deliver to Edmonton. But then I need to find someone to install it and then drive down to irricana and drop off the old one.
I also found that will do a cam and all that stuff + new timing chain and oil pump for 5500-6000.