
Cummins QSB 4.5L Turbo Assembly 2018-2023: OEM 5321679RX
CUMMINS QSB 4.5L TURBO ASSEMBLY 2018-2023: OEM 5321679RX

ORDERS PLACED BEFORE 3PM EST WILL SHIP SAME DAY

WARRANTY
1M MILES OR 1 YEAR
PRODUCT DESCRIPTION
This is a Genuine New, Cummins Turbo Assembly, Cummins part number 5321679RM-WA ( OEM Part Number 5321679RX ).This part is primarily made for a Cummins QSB 4.5L, production years 2018-2023, and comes with a One Million Miles or One Year Warranty. For additional warranty info Click Here
Additional Notes: TUrbo W/ Actuator
OEM NUMBERS
| Primary OEM | 5321679RX |
| Additional OEM | 5321679, 5321679RX, 5326244, 5326268, 5502904, 5604123 |
ADDITIONAL DETAILS
| CONDITION | Genuine New |
| UPC / Barcode | 00840490537514 |
| WEIGHT | 45.00 LBS |
SHIPPING OPTIONS
Ship Weight : 45.00 LBS
UPS Ground, 2nd Day Air, Next Day Air
SHIPPING POLICY
Tamerx Diesel Products ships via UPS Ground. Next day air shipping can be arranged for a reasonable price of anywhere from $50.00 - $100.00 depending on the weight of the product and your location. We will do everything we can to make sure that you get the service you need. We understand how important it is to receive your order as quickly as possible.
In most cases Tamerx Diesel Products only needs one address, as long as your product is shipping to the same location as your billing information. In order to eliminate credit card fraud, your billing information must match the credit card you provide.
The terms, conditions, and details of our warranty vary from product to product. Specific warranty details can be found below.
Tamerx Diesel Products provides a replacement warranty on all of our parts. The duration and mileage limitations of the warranty vary by product and are specified on the product's detail page/item listing.
Please note that the warranty covers replacement of the part and the cost of shipping the replacement part to you only. It does not cover any shop, labor, towing, or any similar or related costs. This is not a "money back guarantee".
If you experience a problem with your part or it is not functioning properly, the correct warranty procedure is to call us at (510) 257-1777 (8:00 AM - 5:00 PM ET Monday through Friday). Be sure to have your order number and/or other relevant order information ready so we can easily locate your order and resolve your issue as quickly as possible. From that point, we will review with you any troubleshooting steps that may need to be taken and other areas or systems that can be checked to rule out external problems contributing to your part's issue. If a replacement is determined to be necessary, we will then arrange for your replacement part to ship out ASAP and issue any necessary return shipping labels and/or documents.
As is the case for the majority of the diesel products sold on Tamerx Diesel Products, your part's warranty is active as soon as you install it. In some other cases, warranty activation is contingent upon you sending us your core (i.e., your old part). Tamerx Diesel Products will provide you a return shipping label for parts that have a warranty with a core return condition. When we have received your core return, the part's warranty coverage begins. We reserve the right to void the product warranty if your core is not received within the allotted time, or if it isn't received at all. If the warranty for the diesel part you are purchasing has a core return requirement, it will be clearly noted on the product detail page/item listing.
What is a Core Charge?
A core charge (also called "core deposit") is similar to the deposit you might pay for a can or bottle of soda and is a standard requirement in the auto parts industry. For example, in many states, to promote recycling, you pay a deposit when you purchase a can of soda and receive your deposit back when you return the empty can. Many automotive parts have a core charge, or core price, that works in essentially the same way as a soda can deposit.
30 Day Core Charge Hold
You authorize Tamerx Diesel Products, to hold your credit card for the specified core charge amount and that you agree to return your core with 30 days of receiving the purchased part. When we have received your core return, the hold is released and the core charge payment is canceled.
The customer, or parts buyer, is responsible for any shipping costs associated with core returns unless otherwise specified in the product listing/detail page. Tamerx Diesel Products offers prepaid UPS shipping labels (SKU numbers UPS-CR1 and UPS-CR2) for use in returning your core that are available for purchase on our website during your shopping/order process.
The shipping label you will need to use for the core return is dependent upon what part you are purchasing. UPS-CR1 is good for cores weighing up to 20 pounds. UPS-CR2 is appropriate for shipping cores weighing 21 pounds or more. You must include enough information with the core return that clearly identifies it as a.) a Core Return, and b.) contains enough information we can use to clearly associate the core return with your order. Including a copy of the invoice or packing slip that came with the original shipment, clearly marked "Core Return", is ideal. Alternately, you can include a note marked as "Core Return" that includes your order number, full name and address, and phone number or other contact information. Failure to include this information with your returned core will most likely delay any due core credit being issued and/or delay any applicable warranty activation. Core returns need to be for the exact part purchased and cannot be damaged. Substituting another part in place of the part you have purchased is not acceptable.
All fluids must be drained.
If you have purchased a set or a parts package, you will need to return cores for all components of the set. For example, if you have purchaed a high pressure oil pump with an IPR valve, you will need to return both HPOP and IPR valve cores to receive proper credit. If you have purchased an EGR cooler/EGR valve package, your core return must consist of an EGR cooler core and an EGR valve core, or core credit will not be given.
Core Charges are often mandated by state legislature, and, as such, the actual core charge and taxes on the charge may vary depending on the state in which you buy your part. The Tamerx Diesel Products core charge presented to you online today with your item is representative of the most common core charge.
Installed on Cummins QSB 4.5L engines produced between 2018 and 2023, OEM 5321679RX is a turbo assembly engineered to integrate with the factory intake and exhaust system layout. This unit is manufactured to meet OEM specifications to ensure accurate fitment and compatibility with existing engine components. Constructed from durable materials, it is built to withstand the operating temperatures and demands common in medium-duty diesel applications. The assembly supports controlled airflow throughout normal engine operation. It is a dependable choice for fleet maintenance and targeted repair needs requiring reliable turbo system functionality.
FITMENT CHART
| YEAR | MAKE | ENGINE(S) | ||||
|---|---|---|---|---|---|---|
| 2018 | Cummins | QSB 4.5L | ||||
| 2019 | Cummins | QSB 4.5L | ||||
| 2020 | Cummins | QSB 4.5L | ||||
| 2021 | Cummins | QSB 4.5L | ||||
| 2022 | Cummins | QSB 4.5L | ||||
| 2023 | Cummins | QSB 4.5L | ||||
PEOPLE ALSO ASKS | BLOG(S)
The Cummins QSB 4.5L Turbo Assembly 2018–2023: OEM 5321679RX is a complete turbocharger unit engineered for QSB 4.5-liter diesel engines used in industrial, equipment, and off-highway applications. While supplied as a single assembly, it is made up of several internal and external components that work together to manage airflow and improve engine efficiency.
Here are the key components of the turbo assembly:
Core Turbocharger Components
- Turbine Wheel and Housing
- Uses exhaust gas energy to spin the turbine wheel, driving the compressor.
- Compressor Wheel and Housing
- Draws in fresh air, compresses it, and delivers pressurized air to the engine intake.
- Center Housing Rotating Assembly (CHRA)
- Contains the shaft, bearings, and lubrication passages that allow the turbine and compressor to spin freely.
Airflow and Pressure Control Elements
- Wastegate or Variable Geometry Mechanism
- Regulates exhaust gas flow to control boost pressure based on engine load and speed.
- Actuator (if equipped)
- Electronically or pneumatically controls the wastegate or variable vanes for optimized performance.
Support and Integration Components
- Oil Inlet and Drain Ports
- Supply engine oil for cooling and lubrication of internal bearings.
- Mounting Flanges and Gaskets
- Provide secure connections to the exhaust manifold and intake plumbing.
- Coolant Passages (if water-cooled)
- Some turbo designs include coolant paths to help manage temperature under heavy use.
Together, these components allow OEM 5321679RX to harness exhaust energy, compress intake air, and support efficient combustion across a range of operating conditions. Proper turbo function contributes to stable engine response, controlled emissions, and reliable performance in 2018–2023 Cummins QSB 4.5L engines.
The main cause of turbo assembly failure is oil-related issues, specifically oil starvation or oil contamination. Turbochargers rely on a constant supply of clean, pressurized engine oil to lubricate and cool the bearings and shaft. When oil flow is restricted, degraded, or contaminated, internal components overheat and wear rapidly, often leading to catastrophic failure.
Oil starvation commonly occurs due to clogged oil feed lines, restricted return lines, low oil pressure, or extended oil change intervals. Contaminated oil carrying dirt, metal particles, or carbon buildup can score bearing surfaces and cause shaft imbalance. Even brief interruptions in oil supply can severely damage the turbo.
Other contributing factors that accelerate turbo assembly failure include:
- Excessive exhaust temperatures from over-fueling or failed regeneration
- Foreign object damage from intake or exhaust debris
- Boost leaks causing overspeed conditions
- Crankcase pressure issues affecting oil return flow
- Poor maintenance or incorrect oil specification
In most cases, the turbo itself is not the original root cause. Underlying engine issues such as injector problems, oil neglect, or exhaust restrictions create conditions that destroy the turbo. Proper lubrication, regular oil changes, clean air filtration, and prompt correction of engine faults are essential to preventing turbo assembly failure and ensuring long-term reliability.
Inspecting and cleaning the oil feed and return passages is advised before installation to help ensure proper lubrication.
It compresses intake air by using exhaust gas energy to improve the engine’s air delivery.
Yes, the complete assembly includes the turbine housing, compressor housing, and center section.
Yes, wear or internal damage can lead to irregular airflow and associated operational issues.
















































































