Engine Issues, Suspected Timing Chains

[Josh Sheckler]

Currently driving an 02 explorer xls 4.0 v6 with 220k miles. Car has had religious repairs and maintenance since it was purchased new from the lot. Several days ago I started it (very cold day, 10 degrees Fahrenheit) and was greeted with a very pronounced rattle and a trouble code. I had no prior issues with the chains. Scanned it and had misfires on cylinders 1, 2, and 3. Replaced the coil pack, plugs, and wires and the codes went away but the sever rattling sound persisted. after driving roughly 20 miles the code came back with the same misfires (1, 2 and 3)....

also issues to note (all of this started at the exact same time, ran like a top prior):
Almost no power in reverse. 4000 rpms moves it at 1mph in that gear.
Very shuttery at low rpms especially at low speeds, but smooth idle in park

Any of this sound familiar to any of you? Personally I feel like all of the cylinders would be misfiring if the chains had broken or skipped...but I know very little about the internals of an engine.

 

[SyberTiger]

I know this sounds weird but....

Take a look at the harmonic balancer. While looking down at the harmonic balancer see if it looks like it's "out of round" or not spinning smoothly. Some folk equate the sound of a bad harmonic balancer similar to a diesel kind of noise plus shaking. And, I heard it can cause misfires.

However, if you've never change out the timing chain tensioners and guide and you have 220K miles it sounds like you are well past due so be careful because maybe it jumped a link and the timing is off.

I seem to recall the 4.0L is notorious for timing chain issues.

 

[Josh Sheckler]

Balancer is fine, I should have mentioned that one. I think i'm just gonna drive it into a river.

 

[drdoom]

Pull the valve cover off the right side, you should be able to inspect some of the timing components at rear.

 

[Tech By Trade]

Chains probably didn't skip, the cassettes probably are all sitting in the bottom of the oil pan. That leaves enough room for it to missfire as it turns the timing out a few degrees. I drove mine home like that from the lake and at RPM it ran fine because the traction side of the chain was picking up all the slack. Drop the pan to find all the goodies. Good news is you probably can do the timing on it if you have the money, time, tools and patience.