Add to this the legendary Allison Transmission behind your Duramax, built on the expertise that has come with decades of heavy-duty commercial and military tactical vehicle transmissions, and its easy to see that the potential longevity of your Duramax/Allison combo is one of the highest quality powertrains in ther light/heavy duty truck market.
Duramax Tech- articles
Injector replacement
Diagnosing an injector failure on a Duramax is fairly straight forward but requires some special tools and service information. we have had our fair share of LB7/Early LLY trucks in the shop which were smoking but the balance or return rate data was within spec, so they were denied coverage under the special GM policy which covers them for 7 years/200k miles. I'm not sure what the options are at that point other than to just replace them out of pocket. which is very expensive.
There are however some things you can do to help minimize injector issues.
*change your fuel filter regularly*
*use a fuel conditioner/lubricity enhancer*
*do not use dirty fuel, or fuel from low volume stations*
* do not use an aftermarket tuning device*(unless you have considered the entire fuel system into the equasion and made modifications that will avoid fuel starvation issues)
To understand injector failures, you must first understand how the fuel system on a duramax diesel works.
Fuel is drawn out of the tank via a tandem high pressure pump which is driven off of the camshaft gear on the front of the engine. it then enters the high pressure portion of the pump where it is regulated and pressurized depending on desired power output, excess fuel is returned to the fuel tank at the injector. there is a fuel pressure sensor on the high pressure side of the system, mounted in the fuel rail assembley. this sensor sends an electrical signal back to the ECM based on pressure. there is also a pressure relief in the high pressure fuel system. this valve is a mechanical device which when maximum fuel rail pressures are exceeded, will open and release this pressure returning it back to the fuel tank passing first through a fluid to air cooler.
What Goes Wrong?
A stock LB7 will at some point, or has at some point, need a set of injectors. these early injectors are a very poor design, and have suffered a high failure rate. they were supposedly re-designed, but we still see about the same amount of failure. One of the reasons for failure is that these injectors require a higher operating voltage than the later injection systems. the electrical section runs hotter and is more likely to have failure.
There was plenty of excitement when GM stepped up and extended the injector warranty under a special policy to replace failed injectors. this policy covers injectors for seven years, 200,000 miles. the rules have recently changed. the problem with this policy is that injector failures must meet certain criteria in order to qualify for covered replacement.
A good example of this would be if your Duramax LB7 is smoking, and all other fuel system components check out, yet the injector balance rates are within the specification, you will not get injector coverage. you are now faced with a four to five thousand dollar repair.
Proper maintenence can help minimize injector failures as well as alcohol free, lubricity enhancing fuel additives.
The 04.5 LLY-07 LBZ
This platform was a definite home run for DMax Ltd. When stock, they have a limited amount of failures mostly related to fuel rail pressure loss due to fuel supply deficiencies-Fuel filter restrictions, and fuel rail pressure relief failure. I have personally never seen an injector fail on its own, though fuel contamination has killed a few.
This system has many safegaurds built in, if you are limping the engine or transmission, the system is trying to tell you something is either slipping or starving, using a band aid fix to mask these issues will only delay catastrophy. aftermarket tuning devices can actually enhance fuel economy, but can also cause damage to the engine and transmission.
Installing a transmission shift kit in an allison transmission which increases internal pressures is a band aid. these transmissions were not designed to withstand the amount of torque for very long, that can be tuned into a late LLY/LBZ/LMM. the old school rule of build it stronger most certainly applies.
The LMM
Once again another home run hit? well, almost. with the addition of a DPF, comes more issues. one issue is of course the introdution of an injection event during the exhaust stroke to light off the DPF during a regeneration cycle. this can cause fuel to make its way to the engines crankcase, and delute the oil making shorter oil change intervals a very good idea.
As this plaform ages, we will see more emerging issues directly related to the DPF.
And as always, you can be sure we will stay ahead of these issues with training and tooling to support our customers who own a Duramax.
If you have any questions concerning your duramax/allison, gove us a call today
Fleet Service Northwest 503-982-5516
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