If it were me, I would pull each one and thoroughly clean each one and see what they look like after that. If they don't clean up well, or don't fully clean the sealing surface, then replace it/them.

 

Hi DMAX, I agree with removing them and cleaning them each very thoroughly I also like to take a small bit of sandpaper and sand down the sealing surface! works very well.

 

I had a 94 Ford IDI (7.3) engine that I did injectors on once. Ford has a tool to ream out the surface in the head the injector seals against (IDI navistar engines don't use injector cups) - which worked great on 7 out of 8 of the bores. Naturally I couldn't get the tool in the passenger side bore by the firewall without removing the AC evaporator... So I did my best to clean the bore out and put the new injector and copper washer in, and hoped for the best.

After about two months and a few hundred miles, the engine developed a terrible knock. I tried everything I could think of, before swapping a 6.9 IDI engine in.

When the old 7.3 engine was out of the truck and on the ground, I decided I'd swap the 'new' injectors over... low and behold the last injector on the passenger side would NOT come out with any amount of effort... Finally said to hell with it and built a slide hammer with an old injector line and managed to get it out, and it was caked up with carbon just like what you have.

Turns out the engine was not toast - but that burned up injector was causing all kinds of problems.

Moral of this story - I'd change the cup out and be damned sure every other bore is perfect

 

Contact Brent at Lincoln Diesel Specialties...

GM Duramax - 2001-2004 LB7 VIN Code 1

GM Duramax - 2001-2004 LB7 VIN Code 1

lincolndieselspecialties.com

 

Wow where does all that rusty stuff come from on the fuel inlet. Looks like that thing is in desperate need of some TLC.

 

I am assuming that just fell in there as soon as I disconnected the hard line. There was corrosion up under the screw-on cap where it meets the tube. The inside of the line and the seal cone area were clean, but disconnecting the line let that stuff fall in there. Almost every injector had that pile of sludge in there after I pulled off the upper valve cover. I am replacing all lines with new ones.

 

That is rust and corrosion from the fitting/nut on the high pressure line that connects to the injector. The LB7 lines seem to do that HORRIBLY compared to LLY and later engines. If the lines have been on any length of time, they will drop that gunk down in the injector inlet when they are taken off

 

Ok, so I ordered all new injector cups and some sleeve sealant. I sure don't want to do this job again. Any recommendations on how to clean the sealing surface in the bore?

 

There was a post within the last month (maybe even 2 weeks) about cleaning the injector cup. Lots of pictures. Do a search and find that thread.

 

Thanks, I will check it out 👍

 

Man, those are ugly. Looks like more than one issue to me. The carboned up tips probably come from the leaking injector which is dumping raw fuel into the cylinder. The gunked up inlet port is probably from water leaking through the connection where the high pressure lines screw onto the injector. I was told to silicone the tops so that water cannot leak past the caps. The gunk around the shaft of the injector could be a leaking cup, or could also be from the water leaking down the high pressure fuel lines. The lines are much cheaper to replace these days, so do not hesitate to replace them. Whata mess. Good luck. I've done mine twice so far and only had to deal with one carboned up injector which makes it hard to pull out of the cup. My truck was smoking at idle.

 

Thanks. I am definitely replacing all the hard lines, and plan on doing the silicone around the cups. I thought my truck ran surprisingly well despite all this. Only one injector had a bad balance rate. That crusty one definitely lost it's copper washer seal, and I am sure that one was making the awful clattering noise on the driver's side. All the other cups are very clean inside. Truck hummed nicely down the highway, and didn't smoke really at all. No coolant use either.

 

X2 on Lincoln Diesel above. Be sure to go with the OEM injectors that have been modified to meet the Warranty requirements for GM. I used remans the first time and they only lasted about 40000 before number 7 started leaking and caused my engine to smoke at idle. Lincoln Diesel should spell all of that out for you. As I recall, they also carry the high pressure lines. One other little suggestion, be very careful with your return lines. I accidentally put a very small bend in one when removing, and could not get it to line up after that. After spending hours I finally purchased a new one. It looks like no big deal, and I thought no sweat, I'll just straighten it. Didn't happen.

 

After you mentioned that about your return lines, I inspected mine closer. I noticed this. Apparently only half the banjo bolt washer was in there? This is on the end banjo bolt right by the failed copper washer injector. I don't see the other half of it anywhere on the head. Wouldn't that have been leaking fuel into the head?

 

So I started pulling the cups, starting with the one that had the failed copper washer. That washer is still down in the bottom, along with a ton of carbon. Good thing I am putting a new cup in there

 

It probably is in there somewhere or fell off on the floor. It would have been a leak into the oil for sure

 

You were right, I found the other half between the head and the firewall. Must have been broken from installation, and the bottom half fell off when I lifted the line out. Glad it didn't go through the engine.

 

Leaking fuel into the oil is a pretty safe bet. Give everything in the fuel system a good inspection. It could have easily ended up down in the oil pan if it broke up small enough. Coppers pretty soft, don't think it will cause you an issue, but that's not good. Hopefully it will come out with an oil change or wedge in some harmless location.

 

So I thought I would post some pictures of the cup seat in case anyone is interested. The cup seat was a little dirty, so I cleaned it up. Then I shoved the camera into the cylinder and looked at the top of my piston. Looks like some oil or fuel pooled on there, I will vacuum that out before sealing the new cup in there.

 

I thought I would finish out this thread. Wow, what a difference new injectors makes!

• My engine is a lot quieter, especially under load
• No more throttle surge under load
• Idle much smoother
• Oil pressure is much better
• Engine starts even when warm, easily
• Did I mention it is quieter?

I also re-did all my battery cables, the entire AC system, the entire glow plug system, the engine block heater and thermostats, rubber fuel lines, and anything else I could clean up and re seal while I was in there. Blasted and painted the valve covers and upper radiator pipe too. Only problem is I have no idea where this bracket that I blasted and painted came from. Anyone know?

 

It bolts on to the ficm bracket, but don't worry about it because mine has been gone for over a decade and pretty much all of them that I've worked on in the last ten years has been missing when I get in there too. It will be fine without it

 

Thanks!

 

Looking good!

 

Thanks!

 

So I just couldn't resist posting one more update. After all this work (replacing injectors, glow plugs, glow plug controller, battery cables, block heater, entire AC system, and a bunch of other stuff), I took the family on a vacation out to South Dakota with the Duramax. After about 2000 miles on this trip, the oil and coolant were still both full, and separate 👍. The truck ran flawlessly, through the mountains, through the Badlands, through Custer State Park, to Crazy Horse and Mount Rushmore. I even squeezed it through the Needle's Eye on Needles Highway in the mountains. I really see the value of a diesel when driving in the mountains. That Duramax goes right up the steep grades without down shifting. I did even realize how difficult those grades are until I started passing gassers with my window rolled down and heard their engines screaming. Hopefully this truck has a lot of life left in it 😁.

 

Nice


Sent from my iPhone using Tapatalk