Other LB7 Duramax problems occur almost exclusively with high horsepower applications. If you are building a high performance truck however, these are things you need to consider.
It might be better to keep your truck in more stock form, therefore making it more reliable. If you decide to pursue higher horsepower and torque, these are some problems you need to be aware of. High horsepower Duramax trucks of all generations are susceptible to snapping a crankshaft. Excessively high RPMs and poor tuning have attributed to some crankshaft failures. Some people also blame the firing order for putting additional stress on the crankshaft.
Breaks typically occur near the number one and two rod journals. Fixing a broken crankshaft is an expensive repair that can result in your truck being in the shop for weeks or months. There are several aftermarket crankshafts that hold up to power better than the factory unit. You only want to have to tear down your motor once.
Another high horsepower LB7 Duramax problem is bent rods. The LB7 Duramax engine has a Instead of breaking and an all-out rebuild being needed, the forged steel rods simply bend.
You can learn more about the LB7 Duramax by visiting some of our other resources. Click on one of the links below to visit that LB7 Resource. Want to learn more about the latest insights in the diesel industry? Signup for our newsletter and stay up to date on the top trending topics! Founder of Diesel Resource and a complete diesel head. Has a little bit of problem buying too many trucks.
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Bosch Dieselogic LB7 Injectors. OTC Discover the worst failure point s of your Duramax in the article that follows, along with how to address it. Perhaps the most devastating of all Duramax failures is a broken factory crankshaft.
The failure is most common in higher horsepower engines, but can still occur in moderately modified and even stock power plants. The crankshaft usually breaks near the number one rod journal due to a combination of excessive rpm and the large external counterweight. A factory firing order that beats up the front area of the crankshaft has also been blamed for imposing undue stress on the crank.
The billet Callies crankshaft available through Wagler Competition Products is machined from triple heat treated V steel and features reduced rod journal widths for improved strength which calls for narrower rods.
For a more budget-friendly option, a properly balanced Compstar forged crankshaft also made by Callies has shown great results in the sub-1,hp arena. In an effort to reduce crankshaft fatigue on the front of the crankshaft, alternate fire camshafts are employed. By changing the firing order of the engine from stock to , the hard hit at the front of the crankshaft is eliminated and the overall load is more evenly distributed across the crankshaft.
Unlike the ultra-durable CP3 that came before it, the CP4. Any time water, rust or debris infiltrates the CP4. Unfortunately, the latter scenario plays out more often than seizures do.
Typically, the roller lifter or bucket that rides on the CP4. Each version of the engine has its own issues and quirks, and some are less problematic than others. This is by no means a comprehensive list of all the problems you may run into, so if you are stumped by your Duramax or just need a little more information to help make the best decision on which parts will help get you back on the road, give us a call at Diesel Power Products, and our team of experts will be able to get you sorted out in no time.
The first Duramax V8 was introduced in and was given the code name LB7. The introduction of common rail injection powered by the Bosch CP3 injection pump made the LB7 Duramax stand apart from other diesels of the day with excellent power and efficiency. As the first batch of trucks started reaching the , mile mark, it became apparent there were some issues with the new engine, and one of the first symptoms exhibited would be a rough idle from the LB7, excessive smoke from the exhaust, long cranking times, and even fuel diluting the oil in the crank case.
We know today LB7 injector failure is a common problem, and because the operating tolerances inside the fuel system are so tight, proper lubrication from the diesel fuel is critical. If you suspect yours are on the way out, the best way to identify which one s are at fault, you need to hook up a scanner and read the balance rates. The trucks computer keeps track of how much fuel needs to be added or subtracted from each individual cylinder to make the engine run smoothly, and this value is called the balance rate.
If one cylinder is contributing too much or not as much as the rest, the cause is usually a bad injector and the cure is a replacement. One of the biggest complaints on the LLY is it has a tendency to overheat, especially when the truck is being worked hard with a heavier trailer or on a hot summer day. While it may not be the first place you think to look, the stock air intake system can actually contribute to a hotter running LLY Duramax.
When the engine is working hard, the turbocharger is drawing in a ton of air, and the restrictive stock turbo inlet tube can effectively choke the VGT turbocharger causing the compressor outlet temperature to skyrocket, heating up the intercooler, and ultimately raising the temperature of combustion and the coolant temp. However, if you install a stock LBZ or aftermarket turbo inlet, you can let the engine breath freely which will lower air temps and keep the coolant temps under control.
It was the first to come bolted to the six-speed Allison transmission which provides a lower cruising RPM and greater fuel efficiency when compared to the five-speed on the LB7 and LLY.
GM worked out most of the bugs by and the LBZ was much more reliable than its older brothers, and on top of all that, the LBZ Duramax was built right before DPF emissions equipment was mandated in While the LBZ was a stellar engine with very few major problems to speak of, one of the biggest complaints is about something GM forgot to install. The CP3 injection pump sits in the valley of the engine between the cylinder heads and is driven by the camshaft gear, and it has two main jobs: get fuel from the tank up to the engine, and pressurize the fuel to 26,psi and ultimately inject it into the engine.
Because the CP3 is doing two jobs at once, it sometimes has a hard time keeping up, but you can help it out with a lift pump. By installing a lift pump with extra filtration from FASS or Airdog you will extend the life of the injection pump and injectors by allowing only the purest fuel into the system, and by feeding a steady supply of low-pressure fuel into the injection pump, it can better focus on its main task of generating high-pressure fuel.
When GM changed body styles with the Duramax, the redesign coincided with some new regulations from the EPA regarding emissions equipment on light duty trucks. Simply put, they can crack under pressure.
The LBZ injector nozzle has seven holes for fuel to spray out of, but the LMM has six which means there are two opposed streams of fuel directly above the wrist pin area of the piston, which causes hot spots directly on top of the weakest area which can lead to cracking. In an effort to keep up with the ever-tightening emission regulations, GM redesigned its Duramax for the model year, and this time the code name was LML. Power was at an all-time high coming in at hp and pounds of torque, and in order to provide this much power while still keeping pollutants low, GM needed to be able to increase the pressure in the fuel system to levels above what the tried-and-true CP3 could safely deliver.
You can be driving down the road and everything seems normal, and when the pump fails, the truck just shuts off. At first you might think you can just swap out the pump for another and hit the road, but sadly this is not the case. Because of the nature of the CP4 failure, large amounts of metal shavings are produced inside the pump, and they get sent straight into the rest of the fuel system which contaminates pretty much everything.
Just like an LB7, you can install a lift pump with better filtration which helps to clean air and debris out of your fuel which will minimize wear and extend pump life. I have a bought new Chevy Duramax with the Allison Transmission. What transmission. All to Duramax light duty pickup trucks came with 6-speed Allison transmissions including my
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