x2 on an injector coming loose either due to loose bolt, broken bolt or broken holddown.
Word of advise in the future, NEVER put your hands near any fuel system components on these trucks while running. The pressures they operate at can cause some severe damage to your hands. Its not different than they teach you with heavy equipment and hydraulic leaks except that its a lot more pressure (Hydro=1,000-7,000psi, CR Diesel 5,000-30,000psi).
In your case no fuel was leaking so you wouldn't get hurt, but you never know when all the vibration could've cracked a line and shot diesel under your skin. Next time use a long pry bar to touch the line to confirm its jumping.
If an injector came unseated you will hear a loud sound that sounds like compression escaping because it is escaping around the injector. With them under the valvecovers on the LB7 they don't shoot a big cloud in the air, but you should still be able to notice the sound. I wouldn't run it anymore than you have to for fear that the cup will unseat and dump coolant into that cylinder.
Finding your issue is "easy" in a way. If you've been around engines its not hard, if youy are new to it then its an intermediate project. Fortunately for you its on the passenger side which IMO is much easier to work on. You don't have to, but most people remove the fender liner and work from inside there. You can also work from the top just as easy. You will want to drain the coolant because it would probably be in your best interest to pull the cup and reseal it. Unhook the batteries of course.
Remove the PCV hose from the front of the motor as well as the valve cover.
Unbolt the aluminum heater hose that runs across that side of the motor. Your choice if you want to remove it or let it hang. 13mm to remove the one nut and one bolt.
Remove fuel filter mount as well as the FICM. You can leave one line hooked to the FICM that runs to the fuel filter if you wish and take them out together. Unhook the other fuel line from the filter head and remove the banjo bolt from the FICM that is for the fuel feed line. Then set aside. 12mm for the three bolts for the fuel filter mount, 14mm for the three bolts for the FICM, 17mm for Banjo. The plugs on the FICM have a locking sleeve you pull away from the connector as you pull the connector away from the FICM. Don't forget the two wires to the Fuel filter housing before removing that as well.
Use 12mm to unbolt dipstick. Remove wires from FICM mount. Use 12mm to remove three FICM mount bolts.
Now you should be down to bare valvecover. Use a blow gun to clean anything from the injector line bores and also along the top edge of the upper and lower valvecover so nothing falls in when you remove them. Use 8mm to remove the screws for the anti spin clips then remove them as well. Use 19mm to remove all 4 injector lines. You can mark where they go if you want but they will only fit back in one way.
Now use a pick to clean out every allen head for the upper and lower valve covers. Get the dirt loosened then use compressed air to blow them out or even better I like to use brakleen in a sure shot. Blasts the dirt out better but doesn't leave a mess. People hate the allen fasteners and I do to, but you can save a lot of headaches by using common sense and taking your time to do it right. Cleaning them takes no more than 5 minutes.
Now use a good 5mm NON-BALL allen to remove all of the allen screws in the upper valvecover only. You can use a ball after you break them loose if you want, but breaking them loose with a ball is risky. The previous techs have likely stripped them for you so you dont want to make life any harder than it has to be. If you do strip one out you can use a multi spline extractor inside the allen to try and remove it otherwise try to get a twist socket around the entire head. I've never needed to use one for the uppers but use a 10mm twist socket all the time to remove stuck/stripped lowers.
Now use a big pry bar with common sense to pry on the tabs along the upper edge of the valvecover. This will break the seal. It takes some force, I use a 4' bar usually but I am not a big guy. Then set upper valve cover aside.
Now use a 7mm to remove the wire nuts from the injectors. The nuts are fastened to the wires so they should not drop. Then use a 10mm to remove the 4 screws holding the harnesses to the rockershaft. Then swing the harnesses out of the way.
Now use a 5mm to remove the lower valve cover screws. The lower valvecover uses a rubber gaskets so you will not need to pry it off. Set it aside.
Now use a 5mm again to remove the 4 fuel return line banjo bolts from the injectors. Again these tend to be stripped by past mechanics. If push comes to shove and you don't have extractors you can use a vise grip but I strongly suggest a new bolt after. You will need to use a 12mm to remove the Banjo bolt that goes into the head and then you can remove the return rail.
The injector hold down bolt can be removed with an 8mm allen providing it's still there. The injector is already popped, but if you ever need to pop an injector you can either use the tool (J-46594 $90) or stick a punch in the holddown (careful to not go into threads) then push it away from the injector to pop it. This uses the Hold down as a lever just like the factory tool.
If the cup is not unseated you can borrow a factory tool ( J-45910) or buy one ($180) or make one homemade. Here is a link to that.
http://www.duramaxdiesels.com/forum/showthread.php?t=31371
If you damage the cup during removal just buy a new one. They are soft and easy to damage, new ones are $20. Reinstall cup with new o rings and red loctite on the tip.
Reinstall injector with new o-rings and copper. Torque hold down to 37-ft-lbs.
Other torque specs.
Fuel Return Line Banjos (always install new return line seals: 12ft-lb.
Lower Valve Cover(gasket replacement optional): 89in-lb
Injector Wire Terminal nuts:18in-lb
Injector harness hold down screws: 80in-lb
Upper Valve cover (clean and install new sealant): 72in-lb twice.
Injector Lines(check for corrosion): 33lb-ft (remember to calculate for your crows foot)
FICM Banjo:20ft-lb.
Parts you will need.
1 Tube The Right Stuff
4 x 97228933 Injector return line seal (Injector side)
1 x 97600925 Injector return line seal (head side)
1 x 97216082 Injector copper seal
1 x 94011699 Injector body O-ring
1 x 94011701 Injector inlet O-ring
2 x 94051259 Injector cup o-ring
1 x 97251047 FICM Banjo Gasket
Optional, or as needed parts.
97228929 Injector Return Line Bolt
97188896 Lower Valve Cover Gasket
97208193 Injector Hold Down Bracket
97221511 Injector Hold Down Bolt
97188463 Injector Cup
That should be what you need, just ask if you have questions.
