Why Did Ram Switch Back To The Cp3 Pump?

When nan fifth-generation Ram HD pickup debuted for nan 2019 exemplary year, it brought pinch it a raft of updates, including a revamped Cummins 6.7-liter inline-six diesel motor offering the Ram a monolithic 1,000 pound-feet of torque successful high-output guise. The motor itself featured plentifulness of caller parts, among them a compacted graphite robust (CGI) motor block, a caller cast-iron cylinder head, a caller alloy crankshaft, stronger connecting rods, and a larger Cummins-Holset variable-geometry turbocharger that forces up to 33 pounds per quadrate inch (psi) of caller aerial into nan engine. 

All of these changes would look to propose that nan caller 6.7L was improved dramatically compared to its predecessor, and rightly so. But Cummins' determination to switch retired nan long-serving Bosch CP3 communal obstruction injection pump for nan Bosch CP4.2 high-pressure injection pump meant it besides picked up a spot of a dent. By nan clip it launched connected nan 6.7L Cummins motor successful January 2019, nan CP4.2 creation had already developed a estimation for failing, from its appearances connected nan 6.6 Duramax LML and 6.7L Power Stroke. 

Unfortunately for early adopters of diesel-powered fifth-generation Ram HD trucks, nan Cummins-equipped CP4.2 pumps saw nan nonstop aforesaid issues arsenic nan earlier versions. It took it 2 exemplary years (2019 and 2020) but Ram yet recognized nan precocious nonaccomplishment complaint of nan CP4 pump and temporarily switched backmost to nan CP3 pump for nan 2021 exemplary twelvemonth arsenic a stopgap solution. The returning tried and existent CP3 injection pump remained successful usage until 2024, erstwhile it was again replaced by a caller Bosch CP8 high-pressure substance pump arsenic portion of updates to nan 2025 Ram Heavy Trucks. The CP3 was besides retrofitted to 2019-2020 Ram HD trucks already built pinch nan CP4 successful a callback that affected complete 200,000 vehicles. 

Perhaps unsurprisingly fixed nan expanding request for vehicles to go much efficient, Bosch designed nan CP4 injection pump pinch a attraction connected weight redeeming and tighter substance power to guarantee amended compliance pinch stricter emissions standards. Overall, nan CP4 is astir 25% smaller than nan CP3. Yet, it pressurizes substance to a whopping 29,000 pounds per quadrate inch (psi) earlier it is delivered to nan communal obstruction system, which feeds substance to nan individual injectors. For context, nan aged CP3 tops retired astatine 26,000 psi.

This use comes astatine nan disbursal of reliability, however. The tighter soul tolerances needed to make nan higher substance pressures mean that nan CP4 creation is little forgiving of debased lubricity ultra-low sulfur diesel (ULSD), aerial intrusion, and substance contamination by h2o and debris. Since diesel substance acts arsenic a lubricant for nan CP4 injection pump, problems tin originate if aerial finds its measurement into substance from nan extracurricular ambiance done a leak successful nan strategy aliases because of improper select installation, arsenic this creates aerial pockets that break down nan fuel's lubricating film. 

Without capable lubricant to forestall clash and wear, nan roller tappet connected nan bottommost of nan piston hits against nan camshaft, and soon enough, each that metal-on-metal action would origin accelerated deterioration of some parts. Eventually, nan hardened metallic particles that are created arsenic nan parts grind down are pumped done nan full substance system, impacting nan injectors, high-pressure substance lines, substance rails, substance tank, and substance filters, starring to a wide substance strategy contamination that necessitates a afloat substance strategy repair which tin upwind up costing complete $10,000, depending connected contamination and parts required.

While nan CP3 is somewhat little businesslike than nan CP4 pump successful position of pumping power, it performs reliably successful real-world usage and this reliability is simply a cardinal logic why it is truthful wide used. The CP3's comparatively generous soul clearances fundamentally mean that it is little delicate to substance quality, and its camshaft creation allows it to person a overmuch smoother activity shape that reduces wear. As a result, nan pump tin past anyplace betwixt 300,000-400,000 miles pinch due maintenance.

With nan CP3, nan nonaccomplishment shape is gradual and commensurate pinch nan pump's property and mileage alternatively than abrupt and catastrophic arsenic is unluckily often nan lawsuit pinch nan CP4. When nan Bosch CP3 injection pump starts to fail, you mightiness announcement that nan motor abruptly loses powerfulness erstwhile accelerating. A struggling CP3 pump is besides often accompanied by signs such hard starts, mediocre throttle response, and debased substance obstruction pressure, among others.