# Service campaign S4325 072025

A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.

- Type: Service campaign
- NHTSA id: 11021335
- Published by NHTSA: 2025\-08\-04
- Manufacturer's number: S4325 072025
- Manufacturer's date: 2025\-07\-08
- NHTSA component: ENGINE

## NHTSA's summary

CBR \- Mack Trucks has identified that certain 2025 model year Mack Medium Duty \(MMD\) vehicles may have been assembled with insufficient torque on the fan hub retaining hardware.

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2025/MC-11021335-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2025/MC-11021335-9999.pdf)

The document is the manufacturer's. This site does not hold it.

## Components

Engine

## Vehicles listed

- 2025 MACK MD

## Other bulletins for the same vehicles and component

- [CBR 2107\-21 202505](/bulletins/11018813.md), 2025-06-02, Service bulletin: FUEL/PROPULSION SYSTEM; ENGINE. Mack DEF Level \(UQLS\) Sensor Troubleshooting Guide \- US17\+OBD16 Emissions and Newer
- [CBR\-561 202503](/bulletins/11016342.md), 2025-04-02, Service bulletin: ENGINE. If oil dilution is suspected refer to the applicable CBR solution below: ∙ CBR\-659􀁡Mack Chassis \- Oil Diluted With Fuel; Fuel In Oil, Diagnostic Information \- All Emissions, All Model Years
- [S4325 202412](/bulletins/11012165.md), 2025-01-02, Service campaign: ENGINE. Mack Trucks has identified that certain 2025 model year Mack Medium Duty \(MMD\) vehicles may have been assembled with insufficient torque on the fan hub retaining hardware. To address this issue and maintain Mack's high\-quality standards, please follow the instructions below to properly retorque the fan hub retaining hardware.
- [CBR\-997 202411](/bulletins/11010857.md), 2024-12-02, Service bulletin: ENGINE. Vehicles may present with oil leak coming from the clutch/flywheel housing and observation of burned clutch smell or clutch slipping. These symptoms can be mistaken as a crankshaft rear main seal leak, when the actual cause is the crankshaft adaptor O\-ring.
- [CBR\-2013 202404](/bulletins/10253807.md), 2024-05-01, Service bulletin: ENGINE AND ENGINE COOLING. CBR: Turbo Compound \(TC\) Hot Side Noise, Diagnostic Information.
- [CBR\-2139 202403](/bulletins/10252308.md), 2024-04-02, Service bulletin: ENGINE AND ENGINE COOLING. CBR: Vehicles built with an 11 liter engine may experience a complaint of excessive fuel in the oil. It is possible that the source of the fuel is the rear fuel galley plug in the cylinder head.

JSON: [/v1/bulletins/11021335](/v1/bulletins/11021335)

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