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Duramax First Generation: 2001-2004 (LB7) Discuss the first generation (2001-2004 LB7) of the 6.6L Duramax diesel engine & associated components. Engine related discussion ONLY. is the premier Duramax Diesel Forum on the internet. Registered Users do not see the above ads.
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Old 01-14-2013, 11:00 AM   #1 (permalink)
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Newbie Questions about LB7

I am looking to get my first diesel and have considered a few LB7 CC 4x4's. What can I expect for mpg's empty on the highway at 65 mph? I found one that the owner said was tuned with light mods and gets 23-24 mpg's, is that realistic? What are somethings I should look for or problem areas. I have read they had injector issues but other than that anything I should be concerned with? What is the avg price to replace injectors? Are new inj mandatory or are rebuilt satisfactory?

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Old 01-14-2013, 12:08 PM   #2 (permalink)
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Every trucks different mpg wise. Ive got 24mpg highway when I was running 33" tires, now I get 19mpg highway with 35's... Hand calculated with my truck in its sweet spot. 70 mph on 33's and 62-65mph on 35's. Injectors and water pump are the biggest issues ive had. Check for any sort of signs its had a tuner or been abused. A lot of these old truck have been beat on. Then check all the normal stuff you should check when buying a new vehicle. I think i paid 2200 ish or so for injectors then 400 for installation. New or reman injectors are a personal choice. Remans have to be build back to LIKE NEW specs so IMO your buying new injectors.

04 Chevrolet Silverado 4x4, LB7 Duramax
- 8in Fabtech Suspension lift
- Airdog 150 lift pump
- PPE Boost Valve
- K&N Cold Air Intake
- EFI Live DSP5 Tuning from Danville Performance
- Industrial Injection R3 40% over injectors
- Edge Insight CTS
- 5" Turbo Back Straight Piped, 3.5" Homemade turbo horn
- BMW Turbo Wheel Upgrade, - MBRP downpipe
- Bilstein 5100 All Around
- Built Tranny from Jim at Maximum Overdrive Transmission
- 35x12.5x17 Toyo Open Country MT

- 521hp@1006trq at Danville Performance 5/2/2012
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Old 01-14-2013, 12:30 PM   #3 (permalink)
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Im assuming you have a Fed Emissions truck? Since even the newest LB7 is now ~9 years old (Ho-lee shiot!), there are some things to look at.

Watch for:

Front hubs needing replaced
Rubber fuel lines on engine and to/from cooler beginning to deteriorate
Bad idler/tensioner pulleys
Rub through on drivers side boost tube (behind P/S pump)
Bad glow plug bus bars (the metal bars attaching all the plugs together)
Pump rub in the transfer case
Rear brakes rusting
Rear axle seals going bad

Thats all I can think of off the top of my head right now.

Your mileage will vary due to your driving style, so nobody else can really tell you "what to expect" based on their experience. Id assume 18-20 unloaded @65mph if you dont drive with a heavy foot. Rule of thumb has always seemed to be "keep it @ 2000rpm or lower for best mileage".

Injectors are, simply put, a "normal" replacement item on LB7s. It sucks, it can be expensive, but its just the price of owning one. Some last a long time, others dont. We dont know why. All LB7 injectors are rebuilds now, there are no "new". That being said, the quality of the rebuilds is important. Bosch remans are usually the best place to start. There is a vendor here who has a good rep, too. You are looking at ~$1700 to start for parts to do the job yourself.

"BBT" 2003 GMC 2500HD CC/SB 4x4
12.14 @ 111.15

"Flyin' Brick"
1999 Chevy 1500 RC/SB 2wd

2003 Olds Aurora 4.0

Success is getting what you want. Happiness is wanting what you get.

Reality is a matter of perspective.

I know just enough to be dangerous.

Last edited by TheBac; 01-14-2013 at 12:39 PM.
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Old 01-20-2013, 02:43 PM   #4 (permalink)
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Buy it, drive it, fix it and repeat!

Seriously though I love my LB7 and the list that TheBac put up is a good start to the issues. I have had the front hub seals replaced, injectors, and I need to do the pulley and belt. The rub on the t-case was repaired before I bought it. I new nothing about diesels when I bought my truck and now I am not afraid to tear into anything with the assistance of this forum that is!
02 Chevy 2500HD 4X4 6.6 LB7 CC/LWB, just over 270K...

AirDog 150, BD Manifold, Alligator intake horn, 5" MBRP straight turbo back, S&B intake, PPE Boost Increase Valve, PPE High Idle Switch, Boost/Pyro pod on overhead console...
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Old 01-20-2013, 04:11 PM   #5 (permalink)
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The mpg is about right. My last long haul, unloaded averaged 24. With the 5er on it is about half of that.

I am on the third set of injectors the first replacement at 50K under warranty. The current set at 75K out of my pocket. Who knows why so soon but it happens. If I were in your position the first question I would ask would be when the injectors were replace and I would be paying the money to have the balance rates checked before buying. Most buyers who show up here bought a used LB7 and then found out it needed injectors and have no recourse with the seller.

I have replaced one rear axle seal and the stock fuel filter head due to leaks other than that it has been routine maintenance.
2014 Chevy Silverado Duramax LML Crew-cab LTZ, short-bed, 4wd.
Fumoto Drain Valve
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Sold: 2004 Duramax LB7

2011 3010 Heartland Cyclone HD 35' Toyhauler

Last edited by lynn1130; 01-20-2013 at 04:12 PM.
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Old 01-21-2013, 07:26 PM   #6 (permalink)
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Mileage depends on the truck and where you are.
I average 21.5 at 65mph. But I am in TN, and have some hills to drive across. I have been as high as 24.4 at 60mph but that was west of KY on level ground.
Problems, injectors are a big one.
Transfercase pump rub can be. (can be fixed)
Steering colum and guages. Have not had a problem with my 03 at 163,xxx miles.
Hubs did replace them at 140,000.
Pretty much everything else is normal wear and tear like brakes and tie rods, etc...
Speaking of brakes if you keep them clean and drive right they will last on these trucks. Rear were replaced before I bought my truck at a dealer (thinking a leaking axle seal) the front are 100% factory. (going to do the rubber lines soon as they are rubber and get old)

Dosen't matter what truck you look at, Chevy, Ford, Dodge they all have their own issues. The question is what year do you want and what brand to avoid the issues you cannot deal with.
Injectors on these are not bad to change at all. Don't be afraid to do them yourself.
2003 2500HD Silverado, ECSB, 3.73, G80, Tekonsha P3, 4" Silverline Dual Exhaust 5" Tips, Autometer Boost & Pyro Guages, Mobil 1 Delvac (TES-295), Opti Lube XPD, 2nd set injectors 109,000, 3rd set injectors 153,000, Cobra 29LTD (peaked & tuned), Wilson 5,000 mileage 172,000
2005 Cavalier 4dr.
1996 1500 Silverado, ECSB, 5.7, 4L60E, 3.73's Powertrax Locker, Lakewood Slappers, mileage 190,000
1974 Corvette, 350, 4 speed, T-tops. Bright red. No tickets yet...
1949 F-1, Flathead 6, 4 speed
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