How do you replace a leaking injector cup?
Replacement requires precision:

Disassemble: Remove injectors and clean the bore.

Extract old cup: Use a specialized puller tool.

Install new cup: Press-fit with sealant (e.g., Loctite 62, then machine or ream for perfect alignment.

Pressure-test for leaks before reassembly.
Tip: Always replace O-rings and inspect injectors for damage.
https://www.cq-longshine.com/cummins-injector-cup

What are the symptoms of a failing injector cup?
Watch for these signs:

Coolant contamination (milky oil or bubbles in the coolant).

Hard starting or misfires due to fuel pressure loss.

White smoke from exhaust (coolant leaking into combustion).

Overheating from compromised cooling passages.
https://www.cq-longshine.com/cummins-injector-cup

What is a Cummins Injector Cup, and what does it do?
The injector cup is a critical sealing component in Cummins diesel engines (e.g., ISX, ISB, or 5.9L/6.7L models). It sits between the fuel injector and the cylinder head, creating a tight seal to:

Prevent coolant/fuel mixing.

Withstand high-pressure fuel delivery.

Protect the cylinder head from corrosion or erosion.

https://www.cq-longshine.com/cummins-injector-cup