Duramax Injectors

[HEEP]

Anyone here changed out a set of LB7 Duramax injectors? Everything I have read states it is just time consuming, not really that hard.:drowninga:

[Brewtal66]

Anyone here changed out a set of LB7 Duramax injectors? Everything I have read states it is just time consuming, not really that hard.:drowninga:

Just asked my buddy about this...he said it took him 13 hours, and cost him about $2300 in parts. And he's about due to do it again.

[camcojb]

I swapped them out on my LMM, not that big of a deal other than getting to all of them.

[BlueSS454]

Just asked my buddy about this...he said it took him 13 hours, and cost him about $2300 in parts. And he's about due to do it again.

That would be me :D. And yes it was a 13 hour job.

It's not overly hard, but is very time consuming. You have to drain the coolant, remove the turbo pipes that go over top of the valve covers, disconnect the wire harness and flip it out of the way then you can access the valve cover bolts. Then you need to remove the fuel filter & pump assembly, disconnect the main fuel lines, leads off the glow plugs, remove the upper radiator hose with the thermostat housing, air filter box and anything else that's in the way.
Next you can remove the individual feed lines to the injectors. You need a crows foot line socket for this.
You will need some metric ball ended hex keys and sockets to remove most of the valve cover bolts. They are not really tight so they should come right out. The hardest part is getting the upper valve cover off. GM uses this sealant that is about as strong as concrete. It took me putting all my weight on a 3 foot pry bar to break it loose. Once that is off, the lower valve cover comes right off. It's a few more bolts and a rubber gasket that is reusable under it.
Once that is all out of the way, you can get the injectors out. There are 8 total. There are retainers holding them in place, remove those and the power wires. There are nuts holding the wires on to the injector itself. Don't worry about losing the little nuts, they stay attached to the wires. Once that is disconnected, the injector can be removed from the cup. I used vise grips to clamp on to it. Twist is a little back and forth then slowly start pulling up to remove the injector. DO NOT yank on it, you risk pulling the cup out with it. If that happens, it will be a whole other set of problems since the cups seal out antifreeze.
Once all the injectors are changed, put everything back together, refill the coolant, change the fuel filter, prime the system, fire it up and bleed the coolant system. Change the oil too since there is probably fuel in it.

[Vince@Meanstreets]

That would be me :D. And yes it was a 13 hour job.

It's not overly hard, but is very time consuming. You have to drain the coolant, remove the turbo pipes that go over top of the valve covers, disconnect the wire harness and flip it out of the way then you can access the valve cover bolts. Then you need to remove the fuel filter & pump assembly, disconnect the main fuel lines, leads off the glow plugs, remove the upper radiator hose with the thermostat housing, air filter box and anything else that's in the way.
Next you can remove the individual feed lines to the injectors. You need a crows foot line socket for this.
You will need some metric ball ended hex keys and sockets to remove most of the valve cover bolts. They are not really tight so they should come right out. The hardest part is getting the upper valve cover off. GM uses this sealant that is about as strong as concrete. It took me putting all my weight on a 3 foot pry bar to break it loose. Once that is off, the lower valve cover comes right off. It's a few more bolts and a rubber gasket that is reusable under it.
Once that is all out of the way, you can get the injectors out. There are 8 total. There are retainers holding them in place, remove those and the power wires. There are nuts holding the wires on to the injector itself. Don't worry about losing the little nuts, they stay attached to the wires. Once that is disconnected, the injector can be removed from the cup. I used vise grips to clamp on to it. Twist is a little back and forth then slowly start pulling up to remove the injector. DO NOT yank on it, you risk pulling the cup out with it. If that happens, it will be a whole other set of problems since the cups seal out antifreeze.
Once all the injectors are changed, put everything back together, refill the coolant, change the fuel filter, prime the system, fire it up and bleed the coolant system. Change the oil too since there is probably fuel in it.

no step by step pictures tom? :buttkick: :mock:

[HEEP]

Sounds fun. and yes, very expensive. This weekend, I'm putting in a new Fuel Pressure Regulator, in hope that it will stop the over pressure and surging issue I have now. It might bring everything within spec. Probably not going to be my luck, but there is hope.

13 hours seems right from what I have read on other sites. So this weekend will be filled with fun.

[BlueSS454]

I had printed out some papers from an article I found on the internet when I did it then. I forget where I found it though. I can look in my folder I keep in the shop when I get home to see if the link is on there somewhere. If I find it, I will post it :)

[LS3torque]

LB7 and LMM are both Duramax motors but night and day different on injector swapping. LB7 injectors are under the valvecovers and the fuel lines pass through the cover. In the middle of 2004 the LLY was born, LLY and all later Duramax had openings in the valvecovers so you could get there alot easier and maybe only change the bad injector. I firmly believe the fuel delivery and filtration systems are to blame for most injector failures, too much dirt being forced past the pintle at 27,000 PSI damages the pintle seat then the injector starts to leak. I have a 1 micron Cat primary filter with a 1 micron Donaldson secondary filter fed by twin Kennedy lift pumps. I have over 100,000 miles with no injector troubles. Good luck to ya.

[TheJDMan]

One of the best sources of Duramax info I have found is http://www.dieselplace.com/

[camcojb]

LB7 and LMM are both Duramax motors but night and day different on injector swapping. LB7 injectors are under the valvecovers and the fuel lines pass through the cover. In the middle of 2004 the LLY was born, LLY and all later Duramax had openings in the valvecovers so you could get there alot easier and maybe only change the bad injector. I firmly believe the fuel delivery and filtration systems are to blame for most injector failures, too much dirt being forced past the pintle at 27,000 PSI damages the pintle seat then the injector starts to leak. I have a 1 micron Cat primary filter with a 1 micron Donaldson secondary filter fed by twin Kennedy lift pumps. I have over 100,000 miles with no injector troubles. Good luck to ya.
I knew it wasn't that hard to swap injectors, but I didn't know there was a change made between the lb7 and the later duramaxs. It didn't take me but an hour or two to do mine so I was sitting here wondering what the heck I did lol.

[HEEP]

LB7 and LMM are both Duramax motors but night and day different on injector swapping. LB7 injectors are under the valvecovers and the fuel lines pass through the cover. In the middle of 2004 the LLY was born, LLY and all later Duramax had openings in the valvecovers so you could get there alot easier and maybe only change the bad injector. I firmly believe the fuel delivery and filtration systems are to blame for most injector failures, too much dirt being forced past the pintle at 27,000 PSI damages the pintle seat then the injector starts to leak. I have a 1 micron Cat primary filter with a 1 micron Donaldson secondary filter fed by twin Kennedy lift pumps. I have over 100,000 miles with no injector troubles. Good luck to ya.

torgue,

I think you are correct. Everything I am reading shows that filtration is the key. I have been running the stock type Wix filter on mine. I finally looked it up a couple of months ago, and it is a 7 micron rating. Going to the _ _ _ type filter, only using Wix again. (Sorry, I work for Komatsu, can't use that three letter word.)
I may add the Kennedy Extra filter under the battery soon. Time will tell on getting this thing done.

[BlueSS454]

Yup, LB7 is in a world of its own. Nothing is easy to do on it plus it's a poor design. There is no water separator on them. When I did mine the first time, there was so much corrosion and rust in the tips of the injectors, 3 out of 8 were almost 100% clogged. I did a balance test on it last weekend and found 1 & 8 bad again. If they were in the same bank I would just change one side. Not my luck. So I'll most likely peel out another $2000 and do all 8 again. Truck has 167,000 on it and going on the 3rd set of injectors.

[HEEP]

Tom,
Have you run the cleaner through yours yet? That did help mine a little. Google the GM cleaner. I ordered from Amazon and it was about $10 cheaper than the dealer. It takes about an hour and a half to process. It bought a couple of mine back to tolerance.

[BlueSS454]

I've never tried that but I'm willing to give anything a shot to not have to do that job again. I do run fuel treatment in it though.

[TheJDMan]

I run 1/2oz of 2 cycle oil per gallon to improve fuel lubricity in my LBZ. I have been running this in all my diesel engines since the 80's and have never had to replace an injection pump or injector in any of my trucks or tractors.

[Wissing72]

The main thing that I saw when changing them when I used to work for the dealer, was looking down into the injector you would see crap where the line screwed in. The metal lines would have rust at the ends indicating corrosion. I would change the lines as well. If there is any corrosion, it will just go into the new injectors. The other thing is the "cups" that the injectors go into seal the coolant passage, so when you pull the injectors (do you have the tool?) you run the risk of loosening them up. They seal with 2 o rings and then I would use red loctite at the tip where it would go into the head. Unfortunately injector failure is a problem with them. I had one truck go through them about every 100k. Also flat rate warranty time was 8 hours for us.... I could do it, but it sucked. Never got to do one on straight time, but 12-13 hours is about right.
Have fun. they are not bad to do, just on your ribs a long time.

[HEEP]

So, I ran the compression test and had one low cylinder. It was 380 and the rest were 400-410. I may go back and run that one cylinder again today. I'm pretty sure I didn't have the adapter tight in the hole, and it may have bled off some.
I did get the Fuel pressure regulator installed and about ready to put fluids back in it and start her up to see if that solved any issues. If you have ever been asked to install one of those, OMG:confused59: that thing is down in a hole and 3 little torx bolts holding them in. I was ready to kill some engineers. HAHA

[Black93GT]

Truck has 167,000 on it and going on the 3rd set of injectors.

Man. Sounds more of a hassle than my buddies 6.0 powerstroke.

I'll stick to my little inline 6. I change the oil and shine the big C on the valve cover. :stirthepot:

[HEEP]

Hmm, keep polishing that "C", I'm sure there are bragging rights that come with that thing. I still love my Dmax.

So I got the truck back together and drove it to work today. The loping has stopped, thank goodness. I still have a little haze in the exhaust, and will probably need injectors. I did install a better filter for the fuel. I hope that helps in keeping better, cleaner fuel to them.

[carkrazy1987]

Get the tool to remove the injectors, makes it a whole lot easier, dont forget to replace the copper washers on the return lines too. Ull need a 5mm allen head for the valve cover bolts, the rear bottom 2 on the driver are the hard ones to get to. Havent done an lb7 in a few years, i used to sit in the engine bay and knock em out in a day. Now all i get is blown up injection pumps on lml, and the demon def fluid issues.

[HEEP]

Ordered the injectors today. I should have them middle of next week, just in time to start on it next Saturday. I have access to the removal tool, my neighbor came down last weekend and he stated that he has changed them before and has the tool. I'll get it from him before I start.