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Our 2006 Commander Limited with 5.7L Hemi and 105,000 miles is throwing a P0306 code for cylinder 6 misfire. We have ruled out the plugs, coil, injectors and now it's at the dealer. They are saying it is either a bad lifter, pushrod, or valve and it may or may not have ruined the camshaft. With the valve cover off and engine running, that cylinder's rocker arms will randomly not move up and down.

I am reading that the early hemis had a design flaw and this is a common problem, so here are my options with cost.

1). Dealer fix the issue, remove head and replace components and reinstall. Total $1500-2200. Risk: this could happen to the other head anytime in the future at the same cost, then I'll have almost $5000 into an engine with 100K miles on the bottom end.

2). Dealer install reman engine with warranty. Total $4000 for engine and $2000 for labor, total $6000

3). Buy reman engine and install myself. I've done many engine swaps and have all the tools/lift, etc. I'll save about $2000 doing this. Not sure I want to spend 3-4 days doing this though.

The rest of the car is in mint shape. What say all of you? Wife loves the car, but I would hate for this to be just the start of a ton of problems...
 

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Doesn't your engine have MDS? Have you eliminated the possibility of a failure in the MDS valve causing the valves to randomly NOT opening?

The little solenoid valve I would think would be ten times cheaper and more easy to replace than pulling the head.

I'd like to know what the flaw was in the Hemi to cause this?

The Hemi has a highly stressed valve train (Cause you have valves on opposite sides of the head, and NOT side by side like other engines), they GenIII that you have, they moved the cam farther up in the block to relieve some of that stress.
 

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Yes, the dealer said he eliminated the possibility of electrical problems and said it was definitely valve/lifter related. I just called and left him a message to confirm the MDS is out of the equation.

These hemi's used inferior metal for the valve seats and are notorious for failure. They fixed this in 07 and on. A quick google search for 5.7 hemi valve seat will tell you all you need to know.
 

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MDS is very much valve lifter related, the way it deactivates a cylinder is by a solenoid valve that redirects oil pressure to the lifters of that cylinder, without oil pressure the hydraulic lifter collapses and does NOT move pushrod/rocker and valve, leaving it closed.

So, the valve sticking in the solenoid valve could very much do this.

BUT, at the same time, Chrysler motors of this era are having valve seat issues and a dropped valve seat could cause the same thing.
 

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Time is the bugger mostly, I am always a proponent of doing it yourself. Great opportunity to make a couple of mods for port and polish, clean flashing off the fluid channels, upgrade to the roller rockers.

Dave
 

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Or throw in a 6.1 or 6.4
 

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Correct me if I'm wrong, but IIUC the MDS was not available on the '06. My '06 HEMI Limited is pretty-well optioned, and yet no MDS. I thought ti wasn't available on the Commander until late '07. ???
 
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