LMM Injector Install Tips - Chevy and GMC Duramax Diesel Forum
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post #1 of 21 (permalink) Old 12-10-2011, 05:39 PM Thread Starter
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LMM Injector Install Tips

I just finished my injectors today and thought i would post a couple quick tips of things that helped and things i did wrong. All in all theyre pretty easy, especially if the EGR is outta the way. All you really need is a 12mm, 17mm, 19mm wrenches. A 10mm, 11mm, and 12mm,13mm, 15mm sockets/ratchet a flat head screw driver and a torque wrench.
New copper washers and O-rings are imperative!
I will post pics and make this more of an official write up soon.

On the driver side you will need to remove the hot-side intercooler pipe, disconnect the 2 big wire harness connectors and remove their holding bracket (2-12mm nuts and a 13mm bolt). Also disconnect the fuel hose and the brackets covering the injector closest to the firewall. Because i did mine when i did the twins, i had already drained the coolant, and went ahead and took the driver sider upper coolant tube off for easy access to the fuel rail.
Im not sure what you have to remove on the passenger side if you have an egr, but if no EGR, it really just removing the intake tubing, maf connector, and close to the firewall you will need to unplug the IAT sensor and pull off the 2 brackets over top the injector. they are 12mm, but the bottom bracket is holding the electrical connector for that injector. Un-clip that and push the bracket out of the way. so you can access the injector.

The 17mm wrench is for the fuel line boot on top the injector, the 19 is for the fuel rail. Once you get them off, keep them in order or you will find yourself mixing and matching for a couple minutes.
take out the return-line holding clip without putting any stress on the plastic "T" on the return line. Once the clip is out, it should pop right out. Then take off the electrical connector.
The injector should pull right out but if not, slide the flat head under the hold down and gently pop it up a little but. A little twisting and wiggling helps as it just the O-ring making it a pain.
The tips on the cap can be pretty tight (torque spec is 45lbs, but mine took about 65lbs to break loose). I put a 20mm wrench in a vise so it would hold the injector upwards while i used the 15mm to break the cap loose. DONT UNSCREW THE CAP ALL THE WAY YET.. there is a tiny puck that will stick to the bottom of the needle and 2 small metal rods that hold the tip in place. (If you lose any of these pieces they will be impossible to find!) Once the cap is loose go to your bench (on my workbench i laid down a towel, then a white sheet over top so i could see any pieces that fell, and they wouldn't bounce away if they fell out.) and finish unscrewing the cap holding the tip. It helps here to push down on the tip to keep it in place as you remove the cap (the old copper washer might make this a pain, but it will pull off easily once the cap pushes it up about half way.)
Once the cap is off carefully pull the tip off making sure the puck/ rods arent stuck to the bottom (its really only the surface tension of the fuel holding them there.) If the puck came out, put it back into the center of the body of the injector, making sure it is flat in there.
There are 3 holes on the bottom of the injector body and only 2 of them are for the rods. DO NOT PUT ONE OF THOSE RODS IN THE WRONG HOLE OF IT WILL FALL INTO THE INJECTOR BODY (one of my mistakes!) If the rods came out, stick them into the bottom of your new tip and then put the new tip (with the needle it should have come with) on the injector body lining up the rods in their holes (when the rods are in the tip, they are spaced so that they will only slide into the correct 2 holes)
Now put your cap back on and wile pushing down on the tip (so the rods dont lose their footing) screw the cap 1 or 2 turns.
--Heres where i had a problem.
Ive never read anywhere that you should use a thread sealant for the cap, but after i did this the first time, i had fuel pushing out of every injector. After about a week of tracking the leak, i narrowed it down to the cap. I got some permatex High-Temp liquid thread sealant, squeezed a bead around the threads, then hand tightened the cap the rest of the way. Wipe off any excess.
Put your injector back in the 20mm wrench in the vise and torque the cap down to 45lbs.
Now put on your NEW copper washer and O-ring.
Before your put it in the bore, its a good idea to clean the bore thoroughly.
An easy way to do this is to cut the long, straight bottom segment off a coat hanger and bend the last 1 inch to make an eyelet. Now put a shop rag in that eyelet and soak it in carb cleaner and stick the other end into a drill. This is nice and flexible so you can maneuver the rag end into the bore and giver her a good spinning to clean it up so the copper washer will seat properly and make a good seal.
Now the injector is ready to go back in. Lube up the o ring pretty liberally (i used motor oil) so the o ring slides nicely in. Put the hold-down back around the body and slide it into the bore. Dont force it. It should thunk in pretty easily with good pressure from 2 fingers, if not, you could be pinching that o-ring (another mistake i made). Once again, a little wiggling might help.
Now put your hold-down bolt back in and tighten it. Then you electrical connector, and return line (the retaining clip can be a PITA cause it likes to fly away if its not right. try your best not to lose it.
Now put the high pressure fuel lines back on, tightening the injector side with the 17mm first. Make sure theyre good and tight or they will leak too.

I pulled them one at a time to simplify it and recommend it.
Now button everything back up, plug everything back in and your done.
Pics will come in the next couple of days.

Twins and trans

'98 GMC Z71 | 5.7L |
'97 GMC Suburban 2500 | 6.5L Turbo Diesel |
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post #2 of 21 (permalink) Old 12-26-2011, 02:20 PM
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any chance on the pics?


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Overpriced HID kits = Obama.
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post #3 of 21 (permalink) Old 01-17-2012, 11:43 AM
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post #4 of 21 (permalink) Old 01-17-2012, 11:49 AM Thread Starter
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Sorry for the delay.. ive been out of town visiting family.. ill post them up when i get home.. should be early next week.

Twins and trans

'98 GMC Z71 | 5.7L |
'97 GMC Suburban 2500 | 6.5L Turbo Diesel |
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post #5 of 21 (permalink) Old 01-17-2012, 12:15 PM
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Thanks for taking the time for the write-up.This is a job that a lot of us dread.Glad to hear that it might not be as bad as feared.

2008 LMM Silverado 2500 LTZ ECSB 4X4.
Aftermarket DSP5 calibration by Danville Performance, Blocked and re-routed, Nicktane with Baldwin BF7587, PPE lift pump with Baldwin BF1212 water separator, 285/75/17 Dura Grapplers on H2s, CTS Insight with pyro.HIDs in fogs and high beams.

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post #6 of 21 (permalink) Old 01-17-2012, 12:34 PM
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07 LBZ White crew cab
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post #7 of 21 (permalink) Old 01-17-2012, 08:47 PM
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sub'd as well

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Originally Posted by 06CCDMAX View Post
a LOT of the Cummins boys like to blacken the highway like an Iraqi oil well burning.
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post #8 of 21 (permalink) Old 01-22-2012, 10:56 AM
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Originally Posted by Tekker View Post
sub'd as well
And another thanks on the write up!

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post #9 of 21 (permalink) Old 01-22-2012, 11:04 AM
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post #10 of 21 (permalink) Old 01-22-2012, 11:38 AM
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