So this morning, I was a little hard on the old boy, WOT getting on the highway....

Drove the 27 miles to work with no issue. This evening I go to start the truck and I heard a very noticeable tapping noise, which sounded like a valve issue. I gassed the truck a bit and could tell it was misfiring and tapping. Stupidly or not, I gently drove it home, misfiring the whole way. Engine light came on about halfway.... P0305 - cylinder 5 misfire. Coincidentally or not, cylinder 5 used to get a bit of coolant in it back when I had the head gasket leak, so I assume it has the most wear of any.

So, failed lifter or valve seat? What's your guess? It'll be parked till I pull off the valve cover. I can't complain though, 313K miles with more to go, once I fix it. I'm hoping for failed lifter & rocker arm fell off, vs having to pull the head.

 

Which engine?

 

Weird that my signature didn't show...

4.7L

 

Pull the valve cover, and have a look. See if anything is obvious. You already know which cylinder you need to look at.

 

Yep pop the VC off and check that rocker. Hopefully you had an intake fail and not an exhaust.

The 4.7 doesn't use a traditional hydraulic lifter being OHC. It's just the rocker arm tappet.

 

Yeah, I'm afraid of what damage I'll find. I shouldn't have driven it home, but that's too late to worry about now. I'm almost positive that when I cranked it up after work, a rocker must have popped out. Hope it's not as bad as this...


At least when I looked at the valve cover, nothing had busted through, LOL.

 

Well guys, I pulled the driver's side valve cover this evening. It's not off completely yet, as the brake booster will need to be loosened up and shifted for it to clear, but it was enough for me to see inside. I was able to confirm that indeed, a cylinder 5 rocker had slipped off. Incredibly, I found no damage to anything, despite driving it for 30 miles. The cam lobes are unblemished and the rocker itself didn't have even a scratch on it. So, it looks like when it popped out, it came to rest in a recess where it wasn't touching anything.

I found no sludge but everything was extremely brown under the cover. Previous owner had horrible oil maintenance habits, so I think it was permanently stained from then. I've been using full syn ever since I got it. There was a bit of white gook/slime under the valve cover itself and I think that might be from running in the cold weather. I think I'm going to switch to a hotter plug (the ones I have run cool).

I expected the offending lifter (valve lash adjuster) to have play in it but it wouldn't budge when I tried to move it up/down with my fingers. So, I'm left wondering why this thing broke loose (aside from the fact I have 313K on it, lol). I already have new lifters and valve cover gaskets sitting in a box, as I was planning to do this job anyway. Now I'm wondering if I should be replacing the valve springs too.

All in all, I consider myself one lucky bastard. Will post some pics when my hosting site get it's act together.

Thoughts?

 

Never really done any internal engine work or know why it may have fallen off, but just to give you some peace of mind I had that happen to an '01 Dakota 4.7 I used to have (RIP), popped it back on and it never happened again.
There is a YouTube video of some dude that added washers or something somewhere (I don't remember) to prevent it from happening again. Might be worth looking into if you're concerned about it happening again.

 

Found an interesting thread. Apparently, you can fix the issue with a washer.

https://dodgeforum.com/forum/3rd-gen...er-arms-3.html

"Case Number K09584712 Vehicle Issue: For vehicles equipped with a 3.7L or 4.7L and a history of repeat rocker arm ejection, especially during cold start in extremely cold ambient temperatures (10 deg. F and colder) There are three major contributors to this issue , dirty or wrong viscosity engine oil , substandard oil filter (which contributes to slow oil pressure build) and possible rocker arm with a shallow lash adjuster pocket;ejection
System or ComponentRocker Arm / Lash Adjuster Recommendation Replace rocker arm with a part that exhibits a tight fit when installed to lash adjuster tip ie. "snaps in place"
Also install a ½" diameter flat washer with a thickness of .020-.030 in the bottom of the lash adjuster bore on the troublesome cylinder .The flat washer will raise the lash adjuster tip enough to maintain proper contact with the rocker arm until correct height is achieved due to full system oil pressure. Always inspect for bent/sticking valve stem , there is a possibility that the valve stem may become bent during the first time a rocker arm is ejected . Also note: the lash adjusters used in the 3.7/4.7L engine are of the NOLA design (Normally Open Lash Adjuster) with this design the lash adjuster will compress easily with finger tip pressure and may give the impression of being "soft" or out of spec.. This is normal for this design, the lash adjuster will increase its internal resistance during rapid compression only"

 

Promised pics so here they go.

Missing rocker




Cam lobes smooth



Rocker - no sign of any damage






Valve cover before starting



Valve cover with wiring and fuel line disconnected and held back with rubber straps... ready to pull the cover