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| Chevy/GMC Duramax 01-04 LB7 Discussion of Chevy and GMC Trucks with LB7 Duramax Turbo Diesel Engines |
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#1
04-08-2009, 01:14 AM
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Replacing Duramax LB7 Injectors 01-04 tips and hints
Last edited by 2500HeavyDuty; 09-09-2011 at 02:30 AM.. 
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#2
04-08-2009, 01:24 AM
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Remove the Keepers on the injector lines with a 8mm socket.
  Then remove the injector lines with a 19mm wrench. If you plan on keeping some of the same injectors and injector lines then you should have a look at this post for more information on the corrosion buildup on the injector lines and injectors. Duramax Diesel Fuel System - Fuel Injector Service   Next step is to remove the upper valve cover. There are tabs sticking out the upper valve cover you can use as pry points. The factory sealant is crazy strong. I tried using a floor jack and it would t budge it kept on picking up the engine.  You can pull the alternator off and use the bracket it for it as a fulfrum for more leverage against the valve cover.    Upper valve cover off 
Last edited by 2500HeavyDuty; 12-22-2009 at 04:40 PM..
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#3
04-08-2009, 12:04 PM
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To get the lower valve cover off you gotta disconnect and remove the injecor wire harness. Its held down to two injectors with four 7mm nuts and two gold 10mm bolts. The 7mm nuts are permanently fixed to the harness so u don't have to worry about loosing them, just the 10mm ones u need to hold on to.
   After Removing them You are now ready to pull the lower valve cover off. using a 5mm ball end allen bit really helps out, also having a variety of extensions helps to when you get close to the fire wall. Pulling the fender liner really helps out when trying to get the ones in the back on the driver side. The bolts aint tight, in fact some of mine were finger loose...  With the lower valve cover off you can remove the injector return line. Be careful with these, try to use a regular 5mm allen bit and tap it in there the best you can because these bolts strip easily. I messed up two of them and i had to use channel locks to remove them.    Picture with the return lines removed.  
Last edited by 2500HeavyDuty; 12-22-2009 at 04:39 PM..
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#4
04-08-2009, 12:27 PM
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All the injectors have a bracket holding them in place, un screw them, they are pretty tight so make sure not to strip them with a 8mm allen bit.
  To pop them out once the injector is loose give them a little twist first to make sure aren't stuck to the cup and then use a small pry bar to pop them out from the top using the bottom of the high pressure supply line on the injector as a pry point and the head bolt as your fulcrum. They should pop right out pretty easily. make sure to remove the copper washer from the bottom of the cup if it doesn't come out with the injector. be sure not to lose the steel button that rests under the bracket that holds down the injector, it usually stays in place, but make sure it doesn't go anywhere.  If the injector comes out with the cup, the coolant from the head will drain into the cylinder if you didnt drain the coolant first.  You can see the gunk built up on the injector that caused it to stick to the cup.   The Injector bore with out the cup in there    Make sure you get all the coolant out the cylinder by bumping the engine over a few times, itl make a huge mess but you gotta get it out somehow. To reinstall the cup clean up the locktite on the bottom of the cup and clean the insides real good and replace the o rings if you can. then prep the cup by using putting red locktite on the bottom of the cup where it begins to taper because that's where it seals with the head. and lube up the o rings with some vasoline or oil. Also clean the mating surface in the head where the cup contacts, need to get it very clean. Be very careful when re installing it and make sure it goes in straight, you can put your finger in the cup and slide it into the bore ad make sure its lined up and completely straight. slide the cup in until the first o ring goes in and check to see if the cup is still going straight down the bore and push it in a little more. GM says to use a brass drift to drive the cup into the bore the rest of the way, you can use a 24mm socket put onto an extension backwards. The extension barely fits in between the valves and since its backwards on the socket it gives it a large flat even surface to drive the cup in. drive it in until its flush with the bore. Last edited by 2500HeavyDuty; 04-08-2009 at 12:32 PM..
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#5
04-08-2009, 01:01 PM
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before putting the injectors back in you need to put on two new o rings
in the picture im pointing where the o rings should be   Re install a new copper washer at the bottom of the injector cup.  and install the injector with the clamp and torque it down to 37 ft lbs  Re install the return lines with new seals. Tighten the banjo bolts to 12 Nm or 106 lbin. Tighten the 12mm banjo bolt that goes into the head to 11 lb ft   Install the lower valve cover and tighen bolts in sequence to 10Nm 89 lbin twice  Install the injector harness and tighten the bracket bolts to 9 Nm or 80 lbin 7mm connectors to 2Nm or 18 lbin 
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#6
04-08-2009, 01:17 PM
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Put a bead of sealant to the bottom of the upper valve cover about 2-3mm wide and 1mm high and install the upper valve cover.
 Tighten bolts to 8 Nm or 71 lbin in this sequence  Install injector lines and keepers  Now put the the FF and FICM back on and ur ready to do the driver side  Thanks to mytmousemalibu (chris) for for giving me tips and hints on replacing the injectors  http://www.duramaxdiesels.com/forum/...ead.php?t=4824 Last edited by 2500HeavyDuty; 04-08-2009 at 01:21 PM..
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#7
04-08-2009, 07:51 PM
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Nice job so did you going with larger injectors?
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#8
04-08-2009, 11:57 PM
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still stock ones  wish i had the money for bigger ones
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#9
04-09-2009, 12:36 AM
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that is alot of work
 but good job
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#10
04-09-2009, 01:45 PM
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Yikes... Nice work/write up Danny
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#11
09-02-2009, 09:26 AM
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question
did all your injector tube's come out when you pulled out the injector? or if they didn't come out did you just leave them in and not worry about it?. GM has a tool for pulling the injectors and the injector cups did you need that?
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#12
09-02-2009, 02:41 PM
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if they didnt come out just leave them there. its a real pain to clean the mating surface of the head where the injector sleeves meet up. the one i pulled out came out because the injector got stuck to it and did not want to let go.
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#13
11-06-2009, 11:22 AM
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Did you use any sealant under the lower valve cover?
You mentioned you did under the upper...but nothing about teh lower. Excellant write up and pics .
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#14
11-06-2009, 12:51 PM
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the lower valve cover uses a rubber seal to seal it up. They are sometimes reusable, depends on how they look. i have had no problems using the same rubber seal 3 times when doing my injectors, the only hard part is getting it to stay on the lower valve cover. I used vasoline and make the rubber seal stick to the lower vc so i can install it.
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