# Service bulletin S7521

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 bulletin
- NHTSA id: 10179303
- Published by NHTSA: 2020\-09\-03
- Manufacturer's number: S7521
- Manufacturer's date: 2020\-08\-20
- NHTSA component: ENGINE

## NHTSA's summary

GU/GR Fan Ring Seal Modification

## The document

- [NHTSA's copy of the document (PDF)](https://static.nhtsa.gov/odi/tsbs/2020/MC-10179303-0001.pdf)
- [If that address does not open, try this one](https://static.nhtsa.gov/odi/tsbs/2020/MC-10179303-9999.pdf)

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

## Components

Engine

## Vehicles listed

- 2020 to 2021 MACK GRANITE \(GR\)

## Other bulletins for the same vehicles and component

- [CBR 2107\-22 202601](/bulletins/11028032.md), 2026-02-02, Service bulletin: ENGINE. CBR \- Mack DEF Level \(UQLS\) Sensor Troubleshooting Guide \- US17\+OBD16 Emissions to US22\+OBD2023 \(DOES NOT APPLY TO AN\(4\) and PR\(4\)\).
- [CBR 199 202512](/bulletins/11027007.md), 2026-01-05, Service bulletin: ENGINE. Vehicles affected by this issue will show coolant runoff on the front rights side of the engine.
- [CBR 2171\-11 202511](/bulletins/11026025.md), 2025-12-03, Service bulletin: ENGINE; ELECTRICAL SYSTEM. CBR \- Mack Temperature Sensor Troubleshooting Guide
- [CBR 199\-6 202511](/bulletins/11026021.md), 2025-12-03, Service bulletin: ENGINE. CBR \- 13 Liter Engines ONLY \- Engine Coolant Pump Housing Leak; Coolant Found Around The Oil Cooler Duct Cover Or In Between The Coolant Pump Housing And Oil Cooler Housing.
- [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 170\-8 202505](/bulletins/11018804.md), 2025-06-02, Service bulletin: ENGINE. Inactive Code P25AE00 Being Generated After A Hard Pull And A Momentary Drop In Engine Oil Pressure \(Low Oil Pressure\) \(Possible Related Codes \- SPN4811 , SPN 100 , PID 100\)
- [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
- [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\-2263 202410](/bulletins/11009705.md), 2024-11-04, Service bulletin: ENGINE. CBR \- Mack Chassis \- Timing Gear Plate Repair
- [CBR\-561 202408](/bulletins/11006925.md), 2024-09-04, Service bulletin: ENGINE. CBR: 11L, 13L, And 16L Engine Oil Analysis Specifications \- US10 And Newer Emissions

JSON: [/v1/bulletins/10179303](/v1/bulletins/10179303)

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