LB7 injector Q's

[z79outlaw]

Me and a guy from work tonight pulled his injectors 2 of them were really rustey in the inlets of the injectors, like little piece of sediment in there they looked really bad. The other one looked like new and the last one was somewhere in between. I figure the fuel rail must be good of all 4 injectors would of been all crudded up. I am I right in thinking that? The line s were the same story 2 bad ones 1 good and 1 somwhere in between. What causes this? Any precautions we should take before reassembly?

We stopped there tonight and hope to have the drivers side pulled apart. Everythings gone good so far, all the cups stayed in and the only problem we ran across was my elbow caused the A/C line to break and I got a face full of freon or wahtevers in there nowadays. I dont think I would hesistate to by a LB7 with bad injectors if it was a good deal now, I had always swore it off but, its not to bad of a project just takes some time to unravel everthing so you can get the the injectors.

 

[S Phinney]

You get rust and crude from water that gets into the fuel system. Just make sure everything is clean when it gos back together and use new seals, washers and fuel return bango washers. Don't over tighten the fuel return bolts us a torque wrench and proper settings.

 

[mytmousemalibu]

LB7"s are easy to get dirt into them when doin injectors. Debris likes to sit in the top of the v/c and fall in when removed, same with crap around the injector seals in the upper v/c. make sure you get it all nice and clean. As for the crap crusted on there, kinda a common thing on LB7's. As Phinny said, careful with the return banjo bolts! The ones at the injectors like to strip the hex and start cross threaded and the banjo at the return/head might bottom out if overtightened and then the return overpressures and you get an internal fuel leak/possible damage. Use fresh o-rings,crush washeres, etc.

You may find some of this helpful! :thumb::hug:
http://www.duramaxdiesels.com/forum/showthread.php?t=4824

 

[z79outlaw]

The job went pretty smooth we had about 15 hours invested in it, taking our time. Drivers side was a royal pain, and his truck hasnt blown up yet, so thats good, I just have him checking the oil to make sure theres no fuel leaks. Torqued everything down to spec so hopefully we'll be all good on that front.

Did have a few mishaps, I broke the a/c line coming out of the compressor that runs to the condenser by leaning on it to hard apparently scared the crap out of me and I took a lung or two full of whatever is in there nowadays and apparently the drivers side valve cover gasket must of came unseated when we put it back on because he said hes leaving little tracks whenever he parks. Just had to be the driver side:rofl: oh well, guess we'll have to tear into it again in a few weeks after deer season settles down.

 

[Vrabel]

LOL I broke mine once too. One night before class I was anxious to put in my ppe valve. Tinman laughed when I moved so fast from sound blasting.

 

[SDE]

The rust you find when you do an injector job is most of the time actually from the line nut itself and not from inside the fuel system. What happens is the nuts that are on the line coming from the fuel rail to the injector actually get moisture in them and are unable to dry out so the bare metal rusts and when you break the line loose all of the rust and corrosion works its way out and falls down into the inlet of the injector making it appear to have come from the inside the fuel system. There is a TSB from GM on this subject. What they say to do is to put silicone around where the line meets the nut at the injector when you reinstall everything to keep moisture out. We've started doing it and it seems to be working good it just looks kinda silly, but hey it works!

Spencer

 

[63chevyll]

do you mean to put spray silicon on the injector threads?
or would something like dialectric grease work? thanks

 

[blowinsmoke]

The rust you find when you do an injector job is most of the time actually from the line nut itself and not from inside the fuel system. What happens is the nuts that are on the line coming from the fuel rail to the injector actually get moisture in them and are unable to dry out so the bare metal rusts and when you break the line loose all of the rust and corrosion works its way out and falls down into the inlet of the injector making it appear to have come from the inside the fuel system. There is a TSB from GM on this subject. What they say to do is to put silicone around where the line meets the nut at the injector when you reinstall everything to keep moisture out. We've started doing it and it seems to be working good it just looks kinda silly, but hey it works!

Spencer

this is true however condensation DOES build up in the mahifold on the lb7's!! Not only will you have rust on the inj tip but also in the lines and manifold itself. GM cleans out every line and the manifold to get rid of the rust accumalation and uses a good quality cleaner such as brake-solv or brake cleaner. any thing that does evaporate! It is a GM requirement to do so every time injectors are replaced. So to answer your question use a really good diesel additive that improves lubricity, removes water and helps keep inj and lines clean!! DieselKleen, howes, amsoil there are alot of em out there. jeff