Recently I've been hearing a tick coming from the 4.0L engine in my '07 Pacifica, 135k miles. The noise is most noticeable after a cold start, there is a slight tick / clatter that can be heard from outside the car.

Sometimes the noise will go away for a few days, but it will reappear eventually, typically after the engine has sat cold for awhile. Presently it's not terribly loud, but I want to take care of the problem before it becomes a bigger one.

Some web searching has turned up a possible rocker arm issue (related to some dowel pin shearing off) with the 3.5L and 4.0L engines and I'm wondering if that may be the cause. There is also a Chrysler TSB regarding the tips on the lash adjusters not being hardened and requiring replacement. Not sure which issue I have at hand here, but has anyone encountered this problem before and what was the solution?

How quickly does this problem get worse and does it cause engine damage if engine is run in this (ticking) condition? I have a trip to Arkansas planned next week and it's doubtful I have time to order new rocker arm assemblies and install them before I leave. Don't want to drive it if it has the potential to become a serious condition quickly.

 

It kinda sounds like the same problem I'm having in a 2010 Routan with the 4.0 V6. Did you ever track down the cause?

 

To be honest I never did figure it out because the problem seems to have gone away on its own. We bought the car at about 130k miles and it would tick for perhaps the first 10-15k of owning it. The tick was loud enough at times to be concerning, but it wasn't so loud that I felt it needed immediate attention. Plus it was fairly infrequent, maybe one out of every 5-10 times I started the car. So I sort of let it be and lived with it a while (presumably until the weather got warmer and I felt like working in the garage to look at it), but then I stopped noticing it and haven't heard it since-- probably a year at least.

For all the research I've done, that symptom (ticking that comes and goes) is related to rocker arm shaft, specifically a pin that shears off, allowing the rocker arm shaft to spin, which blocks the oil holes, resulting in the ticking sound. It's commonly reported on the 3.5L and 4.0L engines. The parts cost about $200 per side if I remember correctly, and the repair is fairly easy for an average skill DIY mechanic.

Here's a video that explains the failure well. My engine sounded pretty much identical. In my case the rocker shaft must have settled into the correct position, but I imagine I'll run into the issue again at some point.

Not saying this is definitely your problem, but due to how common it is, it's certainly something worth checking out.

 

Great video. My Pac w 348,250 mi w/ 3.5 has been making that noise for years. I just grin and bear it, put gas in er and drive the hell out of it.

 

Ticks can go downhill quickly, or sometimes last forever. Either way, it is definitely something that should be addressed as soon as possible. Until you can get it in the garage or shop, I would recommend Sea Foam engine treatment. You can put it in your gas for fuel system cleaning, or put it in your oil to quiet ticks. I had a Ford Exploder that had a tick that I treated with Sea Foam on the regular (about 1 every month) for almost 40000 miles. But it then met its' end when I was pulling a small trailer of firewood up a moderate grade when, from what I believe occurred going by the parts that were damaged, a valve spring broke, valve dropped, collided with piston head, piston basically jackknifed at the bottom of the cylinder...... yada yada yada...... and I got 300 bucks when I scrapped it.