Found new root method and I personally tested this on my phone running ZV5. It will probably root ZV4 as well, but I did not test it. This was written for the LG G2 but appears to work on various LG phones. It works by exploiting download mode to allow the su binary and apk to be pushed to system.
This is not my work, all I did was rewrite it to add more details and make it a bit easier to understand.
This method was found and translated by Unjustified Dev over at XDA for the LG Tribute. You can see his thread and thank him here.. http://forum.xda-developers.com/showthread.php?p=59291717.
Here is the original thread if anyone would like to see it and thank jgkim the original dev but note that the original thread is in Korean.
This is not a one click method and does require a windows (possibly Linux) computer and basic ADB knowledge. You perform this at your own risk. Even though I have tested it on my own phone, I am not responsible if anything goes wrong with your phone due to this guide.
1. Make sure you have the LG Usb drivers installed for the Volt
2. Enable Developer Options - Go to settings > About Phone > Software Information and click on Build Number 7 times.
3. Enable USB Debugging - Settings > Developer Options and click USB Debugging.
4. Download
root.zip and extract to folder on your computer. I recommend putting it on your desktop but any place easy to find will work.
5. Connect your volt to your computer via USB cable and select MTP mode on your phone as connection mode.
6. Open the folder you created above containing the root files. While holding Shift - Right Click in an empty area and select "Open Command Window Here".
7. Enter the following commands one at a time..
If ADB fails, unlock your phone and see if it's prompting you to authorize your PC.
adb push g2_root.sh /data/local/tmp/
adb push busybox /data/local/tmp/
adb push supersu.zip /data/local/tmp/
8. Disconect the usb cable and power off the phone.
9. Power into Download Mode by holding Volume Up button while plugging in the USB cable.
10. Open Device Manager on your computer, Find and expand the Ports Section. Make note of the com port assigned to the LGE AndroidNet USB Serial Port.
11. Enter the following command and substitute your Com port number in place of **
Send_Command.exe \\.\Com**
12. This will put you into a root shell so your prompt should change to a #. At that point enter the following command..
sh /data/local/tmp/g2_root.sh dummy 1 /data/local/tmp/supersu.zip /data/local/tmp/busybox
13 . Disconnect the USB cable and reboot by holding power button until phone restarts
That's is your phone should now be rooted. Make sure you thank the Devs that created and translated this method. If anyone finds this works with ZV4 let me know and I'll update the OP.