Anyone here with an early Duramax, (LB7)?

speeder · 05-31-2021, 07:26 PM

Any long time owners or mechanics who really know these trucks? They seem to be really good w one big caveat, the injectors. Anyone ever have to replace their injectors or conversely, have a high mileage truck with original injectors? Thanks

rfuerst911sc · 06-01-2021, 02:22 AM

I have a 2001 GMC dually one ton extended cab 4x4 that just turned 178,000 miles . I bought it with 98,000 miles on it . I have never touched the injectors but the diesel shop I use said there is evidence they have been changed , the previous owner must have had them done . My truck has been very reliable with routine maintenance done by me .

A few months ago I had the water pump replaced because it started leaking . Two years ago I had to replace the transfer case rear half housing because it suffered the known oil pump wear through issue . The pump is aluminum and the housing is magnesium . The pump slowly wears a hole in the housing . There are several fixes but I decided to use an aftermarket aluminum housing . Been fine since.

That is all I have had to do other than normal maintenance . I do run 16 ounces of 2 cycle oil in every fuel fill up along with 8 ounces of diesel fuel conditioner . I use the 2 cycle oil to add lubricity to the fuel to help the injectors . I love my LB7 because it has zero emission systems on it . I am in the process of adding a Kennedy Diesel lift pump with an additional fuel filter . The lift pump helps take some strain off the CP3 pump .

If I were buying a diesel today I would not hesitate to consider a LB7 as they are very solid . I would budget for a injector repair and just maintain as needed . By today's standards they are anemic in power but I say that tongue in cheek . From the factory mine had 300 hp and 520 lb ft of torque . I have an adjustable GDP controller that can add 100 hp and 180 lb ft of torque . For what I do 700 ft lbs of torque is more than enough . I rarely run it higher than half setting . In the past year or so I have been offered up to 18K for it by folks in parking lots looking for a truck . Not planning on selling anytime soon 😊

cabmandone · cabmandone's Garage

My brother has a high mileage, original injector, early dmax. He credits using diesel kleen in each tank as the reason he's still running on original injectors. Don't know if that's what did it or just pure luck.

Nostril Cheese · 06-01-2021, 04:17 AM

I looked up the procedure for changing injectors on the LB7. Doesnt loo too bad, just a lot of stuff to move out of the way and a special tool to fulcrum the injector from the bore.

Tobra · Tobra's Garage

That is the truck my wife will inherit from her father. He got it to be his retirement, rather than a work truck. 6 speed crew cab with pretty much a Cadillac interior. I had no idea that was even possible. I remember reading an article when they came out and being struck my how implausibly quick they were, even carrying a load. Knowing him, it has had everything done

crb07 · crb07's Garage

I have a Duraburb conversion. Check them out on line.
https://www.facebook.com/duraburbinc/

He put a LLM motor in an 07 suburban for me. Chipped to 450 or so at the wheels.

So, he dumps the old tranny fluid in about 1/4 or a bit more of a tank of diesel and let’s the engine run at about 3k. Says it is the best injector cleaner there is. I also had the factory fuel pump removed and put an Airdog system in. It is a stronger pump and better filtration plus water separator.

look 171 · 06-01-2021, 09:53 AM

When I was looking some years back, I think you convinced me to stay away from Dodge trucks. I agree and noticed the built quality isn't nearly as nice as ford or chevy but the Cummins is a darn good engine. I came from a 12 v.

Read lots about the LB 7 because I came across a few for sale with lower milage, in the 130,000 range. After reading a bit, I noticed many had injector issues and its a bear to get at them. The next gen is much easier, therefor lot less in labor. My truck had its injector changed out right before I bought it. I feed it some 2 stroke oil and Diesel Kleen on every fill up. Not sure if that's even necessary. I have a FASS lift pump. Installed it for the filter itself. I have done or changed everything possible to it to make sure its reliable.

911boost · 911boost's Garage

My neighbor has a 2007, Crew Cab Duramax with the Allison. It has low miles 70K or so and he has had issues with the fuel pump a few times and just recently had to completely redo the front suspension bushing etc to the tune of about $5K. It sees a lot of in town driving and pulls his lighter travel trailer with it.

Oh yeah, the door strip trim is all rusty looking, but that is pretty easy to solve. Overall I'd say it has been fairly reliable and he has had it since new.

look 171 · 06-01-2021, 10:28 AM

I learned that that's typical Chevy or GM front ends on their trucks.

fastfredracing · 06-01-2021, 10:33 AM

Also feed mine 2 stroke oil, and diesel kleen at every fill up, new fuel filter every year . My injectors were done before my ownership at 90 k. Sometimes , they are a little bit noisy, but the truck makes zero smoke, and runs perfect . I have put 50 k on it in my ownership . No diesel issues, only had to do brake lines, fuel lines next, an alternator, and a few small things .
Tuner , 4" pipe, and snorkel air filter, and its a pretty strong running truck . 19mpg from a 4x4 dually going to the beach two summers ago .
I love this truck, its a keeper. I had to do rocker panels also ,Despite me not really driving in winter much, and keeping it super clean, they turned to dust .
It was my first choice for a truck when I was shopping, and still would be today .
No emissions too!!! No cat, egr DPF, nada, do what ever you want . Last of the no emissions diesel trucks .

look 171 · 06-01-2021, 12:49 PM

19 mph is great. I can only get 16.5. once I was able to achieve 18 only once. Normally, I am 16 hwy and around 13 -14 mixed driving. The only thing is, I am always cruising at 80. I often wonder if doing 65-70 will get me better mileage?

rfuerst911sc · 06-01-2021, 12:58 PM

MPG is a combination of a few things . The health of the engine , tire size , speed and gear ratio . My truck has 3.73 axle gear ratio and stock 16" wheels/tires . I have checked several tank runs at 65 mph highway and hit 20 mpg ! That's 6 tires on the ground and a 4x4 and she weighs 7300 lbs. empty . I generally keep 70 lbs of air pressure in the tires .

Mods to my truck are a aftermarket cold air intake and stock exhaust with the muffler removed . I have a GDP adjustable controller that adjusts injectors only it doesn't touch the ECM . That's about it she runs like a raped ape ........... hence her nickname " Kong " 😁

speeder · 06-01-2021, 01:18 PM

Quote:

Originally Posted by look 171

19 mph is great. I can only get 16.5. once I was able to achieve 18 only once. Normally, I am 16 hwy and around 13 -14 mixed driving. The only thing is, I am always cruising at 80. I often wonder if doing 65-70 will get me better mileage?

Is your truck 100% stock or lifted with larger tires?

speeder · 06-01-2021, 01:20 PM

I think that we can all agree that early Duramax trucks are great if stock, maintained by the book and with either replaced or very lucky original injectors. With any diesel, injectors are everything. That and fastidious maintenance, clean oil/coolant/fuel/etc.

look 171 · 01:26 PM

Quote:

Originally Posted by speeder

Is your truck 100% stock or lifted with larger tires?

Not lifted, 275 tires, 17 rim. Maybe that's why is getting 16. Everything else it stock. I do only have 38 lbs in the tires. The bed is normally completely empty.

70 lbs will feel like a bunny hopping down the hwy. My truck is a 4wd also, but not a dually.

look 171 · 06-01-2021, 01:25 PM

Quote:

Originally Posted by speeder

I think that we can all agree that early Duramax trucks are great if stock, maintained by the book and with either replaced or very lucky original injectors. With any diesel, injectors are everything. That and fastidious maintenance, clean oil/coolant/fuel/etc.

Yep. Clean fuel is the key and that why I has the FASS installed. I know that our fuel isn't always that clean sound here.

I don't drive the truck too much. A couple times a months. Its like driving an air craft carries in some parking lots, its a no go.

unclebilly · unclebilly's Garage

I have an 03. The injectors were done before it hit 200,000 Miles. These is a TSB for this that the dealer may honor.

speeder · 06-01-2021, 01:40 PM

Quote:

Originally Posted by look 171

Not lifted, 275 tires, 17 rim. Maybe that's why is getting 16. Everything else it stock. I do only have 38 lbs in the tires. The bed is normally completely empty.

70 lbs will feel like a bunny hopping down the hwy. My truck is a 4wd also, but not a dually.

Well, be careful and check your tire pressure rise when the tires heat up. Under inflated tires will overheat on the highway and can cause blow-outs. You are missing 30-40 lbs. of air in each tire if they are the 10-ply tires that belong on your truck.

speeder · 06-01-2021, 01:42 PM

Quote:

Originally Posted by unclebilly

I have an 03. The injectors were done before it hit 200,000 Miles. These is a TSB for this that the dealer may honor.

That TSB is for trucks with less than 200k miles or 7 years from original date of service, whichever comes first. It's about 10 to 12 year too late for that one, unfortunately.