Buy 4025306 - Genuine Cummins HX40W Turbocharger ISL - wisentpartscenter.com

Description

Cummins 4025306 Turbocharger - Genuine Holset HX40W for ISL

The Cummins 4025306 is a genuine Holset HX40W turbocharger for the ISL 8.9L. It is a fixed geometry turbo with a wastegate, no variable vanes or electronic actuator, so boost is set by the housing and controlled by the wastegate.

Key Functions:

- Fixed geometry turbo with wastegate boost control
- No variable vanes or electronic actuator
- Journal bearing cartridge on engine oil

Fitment & Specifications:

- Cummins ISL 8.9L
- Holset HX40W, fixed geometry
- Wastegated

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

Purpose of the Part

Exhaust drives the turbine, which spins the compressor and forces more air into the engine for more power. The HX40W has no vane control, so the wastegate is what limits boost, bleeding exhaust past the turbine once it hits target. The cartridge rides on engine oil, so oil supply and drain condition is what determines how long it lasts.

Issue Symptoms / When to Replace

Low power and low boost, overboost if the wastegate sticks shut, black smoke, a whine or siren that changes with rpm, oil in the intake or exhaust, blue smoke, and shaft play at the compressor wheel.

Almost every turbo failure comes back to oil or debris. A restricted oil supply starves the bearings, a kinked drain pushes oil past the seals, and dirt through a bad filter or leaking intake wipes out the compressor wheel. Find the cause before fitting a new one.

Brand Information

Holset is owned by Cummins and is the OE builder of the HX40W, so a genuine unit is the exact turbo the engine was specced with. The housing and wheel sizing set the boost on a fixed geometry turbo, so a copy that flows differently will bolt up and still leave the engine down on power or over boosting.

Installation Notes

Find what killed the old turbo first, oil restriction or debris will take the new one out the same way. Check the oil supply and drain lines for restriction, clean any debris from the intake and charge piping, and change the oil and filter. Prime the cartridge with clean oil at the inlet before connecting the supply line, then idle to build oil pressure before loading it. Check the wastegate actuator linkage is free and set.

How to Identify an OEM Part

A genuine unit has HOLSET cast into the housing and a Holset ID tag with the part number and serial number, stamped or peened into the tag, not engraved. Check the numbers match your order. Copies usually have rough castings, missing cast branding, engraved tags or duplicate serial numbers.

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.