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Diesel Service and Maintenance 

Westco Automotive & Truck: Our Diesel Expertise

 

At Westco Automotive and Truck, we don't just turn wrenches—we breathe diesel. With decades of combined experience diagnosing and repairing the Big Three—Cummins, PowerStroke, and Duramax—plus emerging platforms like EcoDiesel, Baby Duramax, and even older mechanical Navistar and Caterpillar engines, we've seen it all. From the infamous 6.0L PowerStroke head gasket failure at 80,000 miles, to VP44 injection pump failures caused by a $30 lift pump, LB7 Duramax injectors buried under the valve covers, and 6.7L Cummins grid heater bolts ready to drop into the cylinder—our team has fixed these issues more times than we can count. Westco Automotive and Truck specializes in bulletproofing, emissions system repairs (EGR, DPF, DEF), fuel system diagnostics (including CP4 pump failure prevention and CP3 conversions), and custom tuning support for daily drivers, hot-shot tow rigs, and fleet vehicles. We stay current with manufacturer TSBs, invest in factory-level scan tools (JPRO, Ford IDS, GM GDS2, and Cummins Insite), and believe in transparent education—not upselling. Whether you're fighting stiction on a cold morning, chasing a mysterious high-pressure oil leak, or just want a pre-purchase inspection on a used diesel, we've likely fixed the exact issue within the last week. Welcome to Westco Automotive and Truck—where diesel engines come to live longer.

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Diesel Engine Deep Dive: Cummins, PowerStroke, Duramax & Beyond

 

Welcome to the ultimate diesel resource. Whether you’re loyal to the 5.9L 12-valve, the 7.3L HEUI, or the LBZ Duramax, we break down the good, the bad, and the bulletproof.

 

1. Cummins (Ram) 

 

The Legend: Inline 6-cylinder durability. Known for mechanical simplicity and massive torque.

 

Common Repairs (All Models)

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  • Fuel lift pump failure (leads to injection pump starvation)

  • KDP (Killer Dowel Pin) – on 12-valve engines, the timing pin can fall out and destroy the gear case

  • Injector & injection pump replacement (VP44 on 24-valve, CP3 on common rail)

  • Front crank seal leaks

Model-Specific Issues

Model Years Common Issues

5.9L 12V (6BT)1989–1998 KDP, fuel heater fires, lift pump failure

5.9L 24V (ISB)1998–2002 (VP44)VP44 injection pump failure (heat + starvation)

5.9L Common Rail 2003–2007 Injector failure, dash cluster failures

6.7L 2007+EGR cooler clogging, DPF regen issues, grid heater bolt failure (can drop into cylinder)

 

Interesting Facts

  • The 5.9L 12V has no ECU – fully mechanical.

  • Cummins has never made a V8 diesel for Ram pickups (all inline-6).

  • The 6.7L’s factory cast iron piston cooling jets are borrowed from mining equipment.

 

2. PowerStroke (Ford)

 

The Workhorse: High-revving, turbocharged V8s. Powerful but maintenance-sensitive.

 

Common Repairs (All Models)

  • Injector stiction (especially 6.0L & 6.4L – oil-driven HEUI system)

  • High-pressure oil leaks (ICP sensor, HPOP, standpipes)

  • Turbocharger VGT cleaning / failure

  • EGR cooler failure (can hydrolock 6.0L)

 

Model-Specific Issues

Model Years Common Issues

7.3L 1994–2003 Cam Position Sensor (CPS) failure, UVCH (under-valve-cover harness) shorts

6.0L 2003–2007 EGR cooler cracks, head gaskets (poor TTY bolts), oil cooler clogging, FICM failure

6.4L 2008–2010 Rocker arm / lifter failure, radiator leaks, regen fuel dilution, cracked pistons

6.7L Scorpion 2011+CP4 injection pump failure (contaminates whole system), glow plug tip breakage

 

Interesting Facts

  • 7.3L is called the "International T444E" – a school bus engine in a pickup.

  • 6.0L can be made reliable with bulletproofing (head studs, upgraded EGR/oil cooler).

  • 6.7L uses a dual-compressor turbo – one small, one large turbine for no lag.

 

3. Duramax (Chevy / GMC)

 

The Refined Beast: Quiet, smooth, and powerful. Joint venture between GM and Isuzu.

 

Common Repairs (All Models)

  • Injector failure (LB7 – under-valve-cover, expensive labor)

  • Fuel filter housing leaks / priming issues

  • Transfer case pump rub (wears through case – creates hole)

  • CP4 pump failure (LML, L5P – less common than Ford, but catastrophic)

 

Model-Specific Issues

Model Years Common Issues

LB7 2001–2004 Injector failure (return fuel line test), injector cups leak

LLY 2004–2005 Overheating (restrictive intake & small radiator), head gaskets

LBZ 2006–2007 Crankshaft position sensor, water pump seals, most reliable

LMM 2007–2010 DPF clogging, EGR soot buildup

LML 2011–2016CP4 pump failure (conversion kits available to CP3)

L5P2017+Emissions sensor failures, glow plug control module

 

Interesting Facts

  • LBZ is often called the “holy grail” – pre-DPF, pre-CP4, strong Allison 1000.

  • Duramax engines have wet-sleeve cylinders (replaceable liners) – rare in light trucks.

  • L5P has a dual-fuel filter system and factory piston cooling nozzles.

 

4. Other Diesel Platforms Worth Mentioning

 

Platform Vehicle Notes

 

VM Motori 3.0LRam 1500 Ecodiesel Common: EGR cooler leaks, oil cooler failures, high-pressure pump failures

3.0L Duramax (LM2 / LZ0)Silverado / Sierra 1500 Timing chain stretch, oil consumption, DEF quality sensor issues

Mercedes OM642 Jeep Grand Cherokee, Sprinter Oil cooler leaks, swirl flap failure, glow plug module

Caterpillar 7.3L / 3116 Older medium-duty trucks Mechanical injection, extremely durable but loud and slow

Navistar VT365 / MaxxForce 7 Ford 6.0L / 6.4L cousins Same issues as PowerStroke – EGR, head gaskets, rocker arms

 

Quick Reference Table – Big Three Reliability

 

Engine Reliability (1–10) Cost to Maintain Best Year

 

5.9L 12V Cummins9Low1998

5.9L 24V (VP44)6 Medium 2001

6.7L Cummins (pre-emissions) 8 Medium 2012

7.3L PowerStroke 8 Low 2002

6.0L PowerStroke (stock) 4 High 2005 (bulletproofed)

6.7L PowerStroke 7 High 2015+

LBZ Duramax 9 Medium 2006–2007

L5P Duramax 8 High 2020+

Interesting Information

Diesel engines don't use spark plugs—they rely on compression ignition (heat from extreme pressure) to ignite fuel, which is why they're more thermally efficient than gasoline engines. The first diesel engine, built by Rudolf Diesel in 1897, ran on peanut oil—proving biofuels aren't a modern invention. A modern turbo-diesel can achieve 40-45% thermal efficiency, compared to roughly 25-30% for a gas engine, which is why semi-trucks routinely log over a million miles. Diesel fuel also has about 15% more energy density than gasoline, meaning more power per gallon. And here's a counterintuitive one: diesel engines actually produce less carbon monoxide and hydrocarbons than gas engines—their bad reputation comes from higher NOx and particulate matter (soot), which modern DPF and SCR systems drastically reduce.

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