Description
PAI Industries FMT-4805 lower radiator insulator set (sold as a pair) for Mack chassis using the 20QL231P12 lower radiator mount. Cushions the lower radiator tank against frame rail vibration, isolating the cooling stack from chassis flex during hauling and idle. Direct OE-form replacement for Mack 20QL231P12, used on Mack universal radiator mounts and on chassis with the E6 2-valve / 4-valve engine.
Specifications
| Manufacturer | PAI Industries |
|---|---|
| Part Number | FMT-4805 |
| Part Type | Lower radiator insulator (vibration mount) |
| Position | Lower radiator tank to frame mount |
| Quantity | Sold as a set of 2 |
| Warranty | 2-year unlimited mileage (PAI) |
Kit Includes
- Lower radiator insulator — PAI FMT-4805 (OEM Mack 20QL231P12) (qty 2)
Cross References
This part replaces or is equivalent to the following part numbers:
- Mack: 20QL231P12
- PAI Industries: FMT-4805
Applications
This insulator pair fits the following Mack chassis and engines:
- Mack E6 engines — 2-valve and 4-valve heads (mechanical and early electronic)
- Mack universal radiator mount applications using the 20QL231P12 lower insulator
Representative vehicles using these engines:
- Mack RD, RB, RW, CH, CL conventional and cabover tractors with E6 power
- Mack DM and MR vocational chassis with E6 / E6 4-valve power
Replace both insulators as a pair (set of 2 ships in this listing). Inspect the upper radiator mount, surge tank straps, and frame-mount fasteners during the same service — collapsed lower insulators usually mean the upper hardware is also taking abuse.









