K Series Parts

There is a Difference

Many competitive parts manufacturers try to reverse engineer Cummins parts and build something reasonably close at a cheaper price. The problem is, these non-genuine parts usually don’t meet critical specifications either dimensionally or from a materials standpoint.

View K Series brochure

Breaking down the difference

cummins part shown over poor performing oem part

We tested 237 non-genuine components for 19L and above engines including pistons, rings, valves, cylinder liners, connecting rods and pins. In virtually every case, issues were identified which would have a negative impact on fuel economy, performance, blow-by, reliability and durability.

Below is a summary of findings for each part, and the danger of using anything but genuine Cummins parts.

View K Series brochure



Issue Damage/Performance
Shallow ring grooves Ring breakage, high oil consumption, blowby, scuffing
Out-of-spec bowl dimensions Excess heat, cracking, high fuel consumption, visible smoke
Debonding of ring carriers Catastrophic engine failure



Piston rings

Issue Damage/Performance
Out-of-spec ring angles
Insufficient sealing, excess fuel usage, decreased performance
Incorrect size of oil ring (too thick) Poor oil scraping, excessive oil consumption
Incorrect size of top ring (too thin) Excess rotation, poor sealing, increased blowby


Piston pins

Issue Damage/Performance
Missing from some kits
Repaid delays, downtime, extra cost
Out-of-spec outer diameters
Incorrect fit issue, repair delays
Intergranular oxidation Manufacturing defect, increased potential for premature fatigue and cracking


Cylinder liners

Issue Damage/Performance
Oversize outer diameters
Radial stress leading to metal fatigue
Insufficient lower outer diameters
Liner rocking and fretting
Oversize inner diameters
Cavitation leading to pitting, coolant leaks and mission-disabling failure
Improper cross-hatching
Compromised lubrication, increased wear, higher blowby and oil consumption, decreased service life
Excess crystals in liner coating
Poor coating adhesion
Insufficient metal strength Premature wear, potential failure


Valve springs

Issue Damage/Performance
Below spec for hardness
Degraded performance over time
Insufficient height load Improper seating resulting in combustion leaks and premature wear-out of valve seat inserts


Valve seat inserts

Issue Damage/Performance
Runout does not meet specifications, can't square to seat Increased wear, combustion leakage, potential valve failure


Connecting rod bearings

Issue Damage/Performance
Tangs too narrow
Interference issues, misalignment of oil holes hindering oil flow
Metals sintered, not cast
Lower corrosion resistances
Excess lead pooling Fatigue cracking


Connecting rod bushings

Issue Damage/Performance
Excess lead in lining layer Delamination and crackin


Saving a little upfront could ultimately cost you

Using non-genuine parts does more than compromise the performance of your high-horsepower engine.

It jeopardizes your business and makes it hard to meet customer expectations. The miniscule amount you save upfront using non‑genuine parts is likely to cost you big time down the road. When your profitability and reputation count on it, use Genuine Cummins Parts to assure continuous performance.

engine icon

Early life

stopwatch icon


dollar sign icon

repair cost



fuel pump icon

fuel cost

engine with alert symbol icon




Only buy Genuine Cummins parts and accessories from
Cummins distributors or Cummins authorized dealer locations

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