more broken timing chain

[skylarkman2]

Newbie but oldie.
Left timing chain broke in my granddaughter's 2004 explorer - 4.0 sohc.
Since I have been repairing/restoring vehicles for over 50 years, I can do this.
First let me say thanks for all the information posted.
A special thanks to 2000streetrod for his clear and abundant pictures and information.
I appreciate that he is not arrogant, accepts different ideas, and admits things he has not tried.
I am adding some of my observations from this process, and some questions that I have not found.
Hopefully this will help others traveling this path.
Instructions are very good for replacing chains because of broken guides. A broken chain changes the picture. In my case the left front chain broke. Since the right chain was intact, I could assume not damage to the right head, valves, or pistons. Removal of the left head looked good, but inspection revealed a minor nick on number 6 piston. Heads will go to the shop for inspection and valve job.

One thing that I think will help is a list of the tools to remove and disassemble these engines. I have a lot of tools in my shop, but still needed some additional. Normal metric sockets, wrenches, pliers, screwdrivers, etc.
Special tools that I found required: (1) tool to disconnect transmission lines to radiator (assuming that you are removing the radiator), (2) tool to disconnect the fuel line from rail. (3) Torx or star bits - size T30 & T55, (4) Torx sockets (external or female) - size E6, E12, & E18.
It is usually difficult to find the individual sockets or bits that you need, and they often come in a set with a lot that you don't need. I wonder why the engineers used these when normal hex heads would have served as well.

Since this one chain broke, I decided that it was best to replace all while I had the engine out.
This is a 2wd model and does have the balance shaft.

 

[skylarkman2]

Continuing:
I note that the right and left cassette assemblies are complete with sprockets and guides.
I am a proponent of not replacing good parts.
Do you think that the balance shaft chain and or sprockets should be replaced?
What about the jackshaft sprocket and crank sprocket?
New guides and tensioners obviously.

I am also looking at how to reset the timing without the OTC 6488 tool set.
Sedition suggested the method of setting the cam with the rear slots parallel to the top of the head.
I note that with the cam in this position, the cam position nub is not in the top position for the sensor.
I am looking at making a tool to hold the cam in position, but I am concerned about the nub position.