How To Change Fuel Filter 2018 Duramax

5 Fatal Flaws of the Duramax—and How to Fix Them

Nov 24, 2018
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Information technology's been said before, but that doesn't make it whatever less true: The 6.6L Duramax is one heck of an engine. In stock grade and even when essentially modified, GM's legendary V8 diesel fuel tin can provide hundreds of thousands of miles of problem-costless use. Yet, and but as we exposed the shortcomings of the almighty Cummins, the Duramax isn't without its flaws—some of them catastrophic. For instance, did you know the injection pump on the LML version is prone to coming apart and wrecking the unabridged loftier-force per unit area fuel system when information technology does? Or how about the fact that the rods in the LB7 and LLY engines tin bend with added power and the LBZ and LMM mills are notorious for cracking pistons? Discover the worst failure point(southward) of your Duramax in the article that follows, along with how to accost information technology.

one. Snapped Crankshaft

Possibly the well-nigh devastating of all Duramax failures is a broken factory crankshaft. Non only does this mean game-over for the engine, but information technology results in a truck that's down for weeks (if not months) and a huge clamper of change missing from your wallet. The failure is most common in college horsepower engines, but can even so occur in moderately modified and even stock power plants. Not specific to 1 version of Duramax in particular (ex: LB7, LLY, LBZ, LMM or LML), the problem exists across all generations. The crankshaft commonly breaks near the number one rod journal due to a combination of excessive rpm and the large external counterweight. A manufacturing plant firing order that beats up the front end area of the crankshaft has besides been blamed for imposing undue stress on the creepo.

Sound Solution(s)

Internally Balanced, Billet Crankshaft

The ultimate fix for the weak manufacturing plant crankshaft is to replace it with a stronger unit of measurement that'southward been internally balanced. The barracks Callies crankshaft available through Wagler Competition Products is machined from triple rut treated 4330V steel and features reduced rod journal widths for improved force (which calls for narrower rods). For a more upkeep-friendly selection, a properly balanced Compstar forged crankshaft (also fabricated by Callies) has shown not bad results in the sub-ane,000hp loonshit.

Alternate Fire Camshaft

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 1-two-vii-8-iv-5-six-iii stock to i-5-6-3-iv-2-seven-8), the difficult striking at the front of the crankshaft is eliminated and the overall load is more evenly distributed beyond the crankshaft. Alternate fire camshafts are available from company'south such as Wagler Competition Products, Empire Operation Applied science and SoCal Diesel.

2. CP4 Failure

This one is specific to the LML code Duramax produced between '11-'xvi, which used the Bosch CP4.2 high-pressure fuel pump (vs. the predecessor CP3 constitute on LB7, LLY, LBZ and LMM engines). Unlike the ultra-durable CP3 that came before it, the CP4.2 doesn't possess the same runway-record for reliability. Any fourth dimension water, rust or debris infiltrates the CP4.two (usually due to bad fuel or lack of maintenance) information technology'southward decumbent to either seize upwardly or come autonomously internally. Unfortunately, the latter scenario plays out more than often than seizures do. Typically, the roller lifter (or bucket) that rides on the CP4.ii'southward shaft (the function that's driven up and downwards via the plunger) fails due to lack of lubrication or droppings hampering its ability to operate in an unobstructed manner.

Sound Solution(south)

Buy Proficient Fuel

When a CP4.2 self-destructs, metal debris is sent through the high-pressure fuel lines, the injectors and the fuel tank. As you lot can imagine, information technology's both labor intensive (a thirty hour job) and expensive (as much as $10,000) to fix. Equally yous might've guessed, water and/or dirt contagion isn't covered nether GM'south warranty, so you'll probable be footing the nib if your CP4.2 goes southward. However, there are measures you lot can have to keep the pump happy and healthy, the first existence to ever buy your diesel fuel from a loftier-traffic, reputable filling station that's known to dispense practiced, clean fuel. Second, always change the fuel filter at or before the recommended service interval.

Add a Lift Pump

Like all Duramax engines from '01-'10, the LML was also void of a lift pump from the manufacturing plant. This means that not but does the CP4.ii have to pressurize fuel as high equally 29,000 psi before sending it to the runway, but information technology also has to pull its low pressure fuel from the tank. We don't exactly know what the CP4.2 requires for low-pressure fuel supply in the LML Duramax awarding, only in the instance of the half dozen.7L Ability Stroke—an engine that likewise utilizes the CP4.2 pump but that receives its fuel from a factory-installed elevator pump—Ford prefers that information technology sees 55 to sixty psi. By installing an aftermarket fuel supply system from company's similar FASS or AirDog you're ensuring your CP4.2 sees steady depression-pressure level fuel supply and adequate lubricity at all times.

CP3 Swap

For utmost peace of listen, the CP4.2 tin be ditched in favor of the tried and truthful CP3. Various aftermarket kits come with everything you need to complete the conversion, mechanically (note that a few ECM tweaks will be required, also). On top of beingness known to last hundreds of thousands of miles without any major issues, the CP3 flows roughly 20-percentage more fuel volume than the CP4.two, so there is as well a slight performance advantage to sending your LML'south injection pump "back in fourth dimension." Companies such every bit Fleece Performance Engineering, H&Southward Motorsports, HSP Diesel fuel, Wehrli Custom Fabrication and many others offer CP3 conversion kits.

iii. Bent Rod(s)—LB7/LLY

We'll be honest, experiencing a tweaked connecting rod in an LB7 Duramax ('01-'04) or LLY Duramax ('04.v-'05.5) is almost exclusively reserved for engines making double the factory horsepower (or more than). Nonetheless, because better than one in four diesel-powered GM trucks is graced with an electronic power-adder, and the fact that this is an enthusiast site, all of you should take note. So what causes the rods to shrink? In a word, torque. Cheers to a 17.5:1 compression ratio (the highest of any other engines in the Duramax lineage), extreme amounts of depression-rpm cylinder pressure (i.e. torque) can be present when you've more than doubled the factory horsepower and torque rating. This stress is direct imposed on the pistons, the rods and the crank—but the rods are the weakest link in LB7 and LLY engines. Luckily, the rods found in these ii engines are forged steel, which is to say that they bend long before they remember about breaking. This means you're usually not in need of a whole new block when this failure strikes.

Sound Solution(s)

Other than dialing back the tuning or scrapping your performance plans altogether to save the mill connecting rods, aftermarket units are in order. CP Carrillo, Wagler Contest Products, Manley Operation, Brian Crower and Howards Cams all offer aftermarket Duramax rods. In addition to its contest-set rods (rated for 2,000-plus hp), Wagler as well offers As-Forged units, which are the most upkeep-friendly Duramax rods in the diesel industry. Conservatively rated to handle one,000hp, they're forged from 4340ACQ, shot-peened to reduce stress risers, come standard with ARP 2000 7/16-inch rod bolts and retail for $i,700.

4. Cracked Piston(s)—LBZ/LMM

Fifty-fifty though the '06-'10 Duramax'due south are equipped with slightly stronger, forged-steel rods than what was used in the '01-'05 engines (LB7 and LLY), the problem moves upward, into the pistons, on the LBZ and LMM engines. Nearly cracked piston scenarios play out at power levels well beyond stock (roughly 650 to 700rwhp for street-driven, '06-'10 trucks), but we've also seen it occur on os-stock Chevy and GMC HDs. Low-quality castings from its suppliers and a reduced corporeality of meat present in the wrist pin expanse (thank you to the use of wrist pin bushings) are to blame for factory piston failure. In nearly cases, the cast-aluminum piston cracks along the center line of the wrist pin, as shown higher up.

Sound Solution(south)

Depending on the type of engine you're edifice, aftermarket piston options range from balmy to wild. For utmost affordability, some enthusiasts opt for de-lipped, LB7-based pistons for sub-700hp builds, while others have comfort in the performance cast units manufactured past Mahle Motorsports or the reworked, oval bowl Mahle units from John "Fingers" McElravy. For many all-out, contest-type builds, forged pistons from Diamond Racing are known to get the call.

5. Leaking Injectors—LB7

One thing the '01-'04 LB7 Duramax is notorious for is injector failure. The two primary failure points of the factory injectors are internal cracking of the injector body itself and corrosion-induced failure of the internal ball seat. The solenoid way Bosch units establish in the LB7 employed a non-hardened internal ball seat to seal the injector. By comparison, later versions of injectors would apply a hardened, chrome-plated ball seat and—non surprisingly—benefitted from much improved durability. Over time, this brawl seat erodes and no longer fully seals. When an LB7 injector begins to leak, yous'll observe the truck hazing at idle and you'll also be able to find abnormally high injector balance rates (the corporeality of fuel each injector contributes to maintain a smooth idle) with the appropriate diagnostic equipment. To add insult to injury, a leaking injector ways a considerable amount of fuel is making information technology into the crankcase.

Sound Solution

Located underneath the valve covers, there is nothing cheap near replacing an injector on an LB7. For this reason, nigh shops recommend you replace all eight injectors as opposed to doing them one at a time. LB7 injector replacement performed at an independent shop typically calls for x-12 hours worth of labor and roughly $3,500. No matter where you take the truck for the job or whoever performs the work, make sure you install brand-new, 18-carat Bosch injectors. The latest Bosch versions feature an improved body (no corking), a hardened, chrome-plated brawl seat (no leaking) and DLC coated nozzles for unmatched long-term immovability.

Know yous want a Duramax but not certain which ane? Read out Duramax Buyers' Guide!