The LB7 Duramax is a diesel engine manufactured by General Motors. It has been in production since 2000, and it is still widely used today. This engine’s fuel injectors can fail for several reasons, including the use of the wrong fuel additive, overuse of stanadyne, and more.
This article will cover best diesel fuel additive for LB7, some of the reasons for injector failure, and what you can do to avoid them so that your LB7 Duramax will last longer.
Contents
Should I use a fuel additive in Duramax?
Based on some of the tests I’ve read lately, I think I will switch from Diesel Kleen to Opti-Lube XPD. I wish there were a local place that sold it.
Before switching to Schaeffer Oil | Diesel Treat 2000 Fuel Additive, I used the double dose rate on the Summer+. Downerrr misleading on Opti-Lube’s part, I think, in leading you to use twice the rate as needed.
What Diesel Fuel Additive Should I use?
Both injector businesses that I use recommend Stanedyne. I run a mix of cenpeco power max and marvel works very well. Then I run 1oz of Super Tech 2 stroke oil per gallon of fuel per fuel up.
In the winter, I use Diesel Kleen in the grey bottle year-round as it does not get too cold for me to worry about gel. If you live where it gets really cold, use it.
Diesel Kleen is not the best or the worst on the market, but it is the easiest for me to get at Walmart and or Tractor Supply depending on where I am at the time I need more. I think GM recommends Standyene, but I am not sure.
You’ll want to study the market more and figure out what makes the most sense for you. Volume-wise, the cost per liter decreases as you purchase more.
Is too much Stanadyne bad?
I’m curious about what people put in their fuel as an additive. I’ve heard a lot of varying opinions about two-stroke oil and opting for Stanadyne, which I use every time after I top up with liquid Optilube or Power Service’s Diesel Kleen.
Lately, I’ve been using the super tech 2 cycle oil, and it seems to be running smoother. Balance rates are better as well.
Is the LB7 that bad?
I just got my 2004 Duramax! I’d love to know when I should change the oil and what other core services I should be doing. We do not think you need to change your transmission fluid or differential gear oil but would like to take a look at the engine for an official diagnosis.
To access the fuel filter, first, take out the passenger-side inner fender. It’s also a good idea to get a spacer that will allow you to move the fuel filter closer to the motor for easier access.
I would recommend that you not fill the filter. There’s a primer on top of it and a bleed screw underneath. The fender liner shouldn’t be messed with either. Some places in WA have put 10% biodiesel in their fuel during the winter months due to the government being in charge of fuel distribution.
I own an 05 ply engine. Replaced transfer case as it had a seize, causing the bearing to wear down. I injected both injection pumps but was told they’re nearly bulletproof. Injectors cost around $400 each.
01-04’s were hard on injectors. It seems you have to replace them every 50,000 miles or more once they get above 100,000 miles on it. The Duramax’s are the most powerful and have the best mileage.
Will diesel additive affect the lift pump?
A diesel additive will not affect your lift pump. You can tell whether or not your additive is safe for the FWS filter by checking if it is alcohol-free and a demulsifier. If it’s both, you’re good to go!
I just recently switched to Opti-Lube after reviewing some lubricity tests. If you read up on the lubricity requirements for bosch high-pressure fuel pumps, you will discover that the fuel sold here in the US does NOT meet its lubricity requirements.
Bring it in and find out the injection rate. The lb7 is a great engine but has poor injection. I have one; it’s a great truck!
Just run a lift pump with extra filtration, have a clean fuel supply, and use additives like stanadyne or opti-lube every other tank. An aftermarket lift pump will help eliminate air and provide better filtration. I’ve been told that a lift pump will make a massive difference in injector life.
What causes LB7 injector failure?
The LB7 motor has some issues with EFI Live. EFI Live is a great product, just a glitch with that particular model.
You’ll know that the more HP you throw at it, the more pissed off it will get. The Allison transmission is one of the best tranny’s.
Duramax engines made before mid-2004 have injectors that are very costly to replace, and in later 2004 models and newer, they made it, so the injectors are easier to get.
As for injectors, they got replaced by GM after a recall years ago. I’ve used a truck to haul my tow boat all over the west coast. I also did it with a Haulmark attached for extra space.
It’s been programmed(hyper-tech) w/ a larger exhaust since 45k miles. It’s got about 170k now, and the only problem I’ve had is w/ the transfer case.
At almost 250k miles, I doubt injectors or pump rub would be an issue. Mileage is killer compared to other Dmax’s. You should see 20 mpg all day long with 31-33 tires. I just went to 34s with the 20s, and I’m still running about 17-18 mpg mixed-used. I never came across any threads about EFI glitching with that motor.
Heat is what I’ve been told and the only reasonable explanation. There are “revised” injectors, but they fail also. Maybe where the injectors are oriented in the head has something to do with it.
How to check LB7 injector failure
Around 150000, the injectors start going. Get the flow rates checked. You can find this service at a nearby dealership using the tech 2 scanner.
If the truck smokes or has a lope to it even though the injector rates test good, then that’s still a sign they need replacing. Aside from that, tie rods are a known weakness if you use your 4wd a lot but cheap.
It sounds like the injectors are due to be replaced then. I’ve had similar experiences with old cars that needed new injectors before then. The good news is it’s also a relatively inexpensive fix for about five thousand dollars.
What’s the difference between LB7 and the latest models
So, what’s different between LB7s and later models?
For the newer ones, GM installed the LLY injectors outside and then increased the voltage. They decreased the voltage on LBZ, and the rate dropped. The LB7 injectors started as original bosch and were brought over from Europe.
