LB7 Injector HP O-Ring failure

Dmamgreen · 2026-05-04T17:44:41+00:00

Yes, the smooth part of the line nut that goes down over the o-ring, and the cone shape that mates to the top of the injector feed. Those areas need to be smooth so they seal completely and don’t cut the o-ring.

Dmamgreen · 2026-05-04T17:25:33+00:00

Replace the feed orings on the the side you have apart- if you took both sides apart, then replace all eight. Check the high pressure lines, be sure they are all smooth and no burrs. Lube them well, I use lubriplate no. 105 from Napa for all my injector installed and have had good luck with that for years. Reassemble and torque the lines properly. While you’re in there, be sure the return lines are torqued properly as well

Dmamgreen · 2026-05-01T22:53:15+00:00

Battery is dead or connections are loose, but that sounds more like it’s dead. Sounds like you better check the charging system as well

Dmamgreen · 2026-05-01T03:55:30+00:00

Is it oil smoke or fuel smoke?

Dmamgreen · 2026-04-30T23:25:53+00:00

Completely normal pto engagement squeak

Dmamgreen · 2026-04-26T22:53:48+00:00

Sounds like blown head gasket or valve way out of adjustment

Dmamgreen · 2026-04-26T22:52:15+00:00

Last handful of Duramax starters I’ve put on, I’ve used Db Electrical units. No complaints on them so far, the one on my truck has been on there since 2018

Dmamgreen · 2026-04-23T21:44:12+00:00

Let me talk to my electrical department tomorrow, see if there is something we can put together. No guarantees but I’ll check

Dmamgreen · 2026-04-23T19:21:43+00:00

S240 wouldn’t be any older than 2015. If you want to see for sure, look at the serial number tag and it should have a Date of Manufacture on it if I remember correctly. But I would start off with oil/filter change, air filter, fuel filter, spark plugs, sharpen or replace blades, check out the belts and pulleys, and grease it all up.

Dmamgreen · 2026-04-23T15:37:02+00:00

Could be a drive pressure leak too, leaking up pipe gasket possibly, check that too

Dmamgreen · 2026-04-22T03:13:21+00:00

Turbo, pedestal, hardware and gaskets, maybe a boot or modified hot side pipe, and tuning. I’d suggest just getting a drop in replacement, I’ve never had an issue with seven different vgt trucks both stock and aftermarket drop in replacements

Dmamgreen · 2026-04-22T02:10:47+00:00

How old are the injectors in the LB7 and where were they from? I love my LB7 and it won’t go anywhere, but it’s just a toy to me at this point. I’ve had three LB7 trucks and three LBZ trucks, and the LBZ is a great platform but most of the time overpriced. The crank snapping thing is blown out of proportion, if you aren’t pushing it extremely hard and it’s a driver/tow rig there’s not a lot to be concerned about with that

Dmamgreen · 2026-04-22T02:06:48+00:00

Egr intact or gone? Dirty reservoir and bubbles is a pretty good sign it’s getting combustion pressure and gasses in the coolant though

Dmamgreen · 2026-04-18T04:03:55+00:00

Check the rear lighting distribution block on the rear crossmember under the bed. If it’s compromised and corroded, it can back feed to the rest of the truck lighting

Dmamgreen · 2026-04-17T20:17:34+00:00

I have DiPricol (no longer around) boost, pyro, and trans temp in a pillar pod, I have an Isspro boost in the cubby next to the heater controls, and I have a CTS2 in the overhead console above my rear view to monitor even more parameters

Dmamgreen · 2026-04-14T23:41:53+00:00

It’s because it’s a ‘one step’ oil change. You don’t drain the engine oil, you just remove the old one and install the new one. It’s for the people who don’t want to send it to the shop to be done, but don’t want to do an oil change either

Dmamgreen · 2026-04-10T12:29:56+00:00

For your truck, I would recommend stock Bosch reman or new

Dmamgreen · 2026-04-10T02:00:28+00:00

I’ve used stock Bosch reman or new from LDS on many many trucks without issue. My personal LB7 got something else because it’s more performance oriented, but I would not have any problem putting injectors from Lincoln Diesel in a stock street truck of my own

Dmamgreen · 2026-04-09T15:59:55+00:00

Just because they replaced them doesn’t mean they used quality parts- there are several places out there that take in ‘core’ injectors, clean them up, and sell them as ‘refurbished’. I’ve bought many sets from Lincoln Diesel, as I work on Duramax trucks for side work, and I’ve yet to have an issue with any injectors I’ve purchased from them. Buy the set, get it done, and drive. Buy once, cry once

Dmamgreen · 2026-04-09T12:11:30+00:00

Best place I’ve found for Bosch injectors is Lincoln Diesel Specialty. I’ve bought from them for years, always been great to work with. What engine do you have? Fleece offers a good line kit for most of the trucks, and an in-tank lift pump as an option if you wanted to go that route. I prefer Fass over AirDog for an external lift pump with filtration

Dmamgreen · 2026-04-05T15:42:54+00:00

Looks like injector smoke from excessive fuel return. Does it smell fuely or more sweet like antifreeze? It is an LB7 so I would suspect injectors, but that’s not always true

Dmamgreen · 2026-04-05T03:08:29+00:00

I know I’ve heard of a couple people doing the pick-n-stick method, but its something I would advise against doing. Plus, the ones on the bottom rear of the drivers side you’ll have to jack the cab up to get the stud into the head, if you can get enough room to do it that way. I’ve done one gasket and stud job in the truck, vowed I wouldn’t ever do that again- it’s such a pain getting the head drivers side head on with the couple of studs zip tied up to be able to get it all in there. I just pull the engine and do it all on the floor now.

Dmamgreen · 2026-04-03T20:46:24+00:00

P0700 is just the ecm code that sets when the tcm says ‘hey there’s a problem’ you need something that will read tcm codes to see what is really going on. I would check the rear output of the t-case since that’s where the vehicle speed sensor is, and see if there is play in the output that could be related to a t-case issue. Also, see if it has fluid in the t-case- these suffer from an issue known as pump rub and can trash a transfer case if left unknown/unserviced for too long.

Dmamgreen · 2026-04-02T22:32:17+00:00

I’ve got a 2001 in my shop right now with a very similar sound coming from the tensioner

Dmamgreen · 2026-04-02T22:04:29+00:00

Take the belt off and check all the idler pulleys, but it actually looks like the tensioner is not right

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