wp20328 - Genuine Cummins / Wabco Air Compressor - 2 - wisentpartscenter.com

Description

Cummins 5266300 Air Compressor - Genuine Cummins Wabco Air Brake Compressor for ISB and QSB 6.7L

The Cummins 5266300 is a genuine single cylinder Wabco air brake compressor for ISB and QSB 6.7L engines, EPA07 and up. It is gear driven off the engine and builds the air pressure for the truck's brakes and air systems. Water cooled and lubricated off the engine. Includes mounting gaskets.

Key Functions:

- Builds and maintains air pressure for the brakes and air systems
- Single cylinder, gear driven off the engine
- Water cooled, engine lubricated

Fitment & Specifications:

- Cummins ISB and QSB 6.7L, EPA07 and up (2008 to 2024)
- Single cylinder, 145 psi max, 3000 rpm
- 3.35 in bore, 2.20 in stroke
- Gear drive, includes mounting gaskets

Verify fitment with us before ordering to ensure the correct part for your application.

Purpose of the Part

The compressor keeps air in the tanks so the brakes work. It runs off the engine gear train and the governor cuts it in and out to hold the system between cut in and cut out pressure, running unloaded when it is not building air. On a truck, no air means no brakes, so it is a safety critical part. It is cooled by engine coolant and fed oil from the engine, so those supplies have to be clean and flowing.

Issue Symptoms / When to Replace

Slow air buildup, the system not reaching cut out, knocking, and oil passing downstream into the air dryer and tanks. Excessive oil passing is the common one, it fouls the dryer and lines and usually means worn rings.

Before replacing it, check the governor, the air dryer and the lines for leaks or restriction, since those cause slow buildup with a good compressor. If the old one was passing oil, replace the dryer cartridge too, oil carries downstream and fouls the new setup.

Brand Information

Cummins sources this compressor from Wabco and sells it as a ReCon unit, remanufactured back to original spec with worn parts replaced, not just cleaned up. On a part that feeds your brake air, that matters. A cheap rebuild that passes oil or does not build pressure right fouls the air dryer and leaves you doing the job again.

Installation Notes

If the old compressor was passing oil, replace the air dryer cartridge and check the discharge line for carbon buildup. Oil and debris carry downstream and will foul the new compressor the same way. Prime the oil feed before startup so it is not run dry, and use the mounting gaskets included.

How to Identify an OEM Part

A genuine unit has the Cummins C logo cast into the crankcase along with the Wabco casting numbers, not printed or stickered. Check the part number matches your order and compare the head, ports and mounting flange to the compressor coming off. Reman units are marked as Cummins ReCon. Copies usually leave the C logo off, have rougher castings, or different port locations.

Why buy from Wisent Parts
  • ⏱️
    Fast shipping
    Orders before 12PM EST ship same business day.
  • 🛡️
    180-day warranty
    All parts covered from delivery date.
  • ↩️
    Easy returns
    30-day returns.
  • ✅
    Verify fitment
    Send VIN/ESN and we’ll confirm.

Shop with confidence

Warranty & Return Information
Warranty Information

Wisent Parts offers a 180-day warranty on all parts from the date of delivery. This warranty covers orders placed directly through our website. If a part fails during this period, we’re here to help - whether it’s a replacement, repair, or refund. For full details, refer to the Warranty page.

Return Information

Wisent Parts accepts returns within 30 days of delivery. All returns are subject to a restocking fee. To qualify, parts must be unused and in their original condition. For full return instructions and restocking fee details, please refer to the Returns page.