Volvo/Mack MP8 Injector Hold-Down Bolts
The MP8 injector hold-down uses a clamp-style mounting. Proper torque prevents injector lift and combustion gas blow-by. These are torque-to-yield bolts — replace on every removal. The MP8 uses a common rail system with rail pressures up to 29,000 PSI — injector sealing is critical.
Important: These torque specs are reference values. Always verify against your OEM service manual for your specific engine serial number and build date. Torque-to-yield bolts must be replaced — never reused.
Torque Specifications
| Step | Torque Value | Notes |
|---|---|---|
| Lubrication | N/A | Apply clean engine oil to bolt threads and under bolt head. |
| Pass 1 — Snug | 15 ft-lbs (20 Nm) | Hand-snug all injector clamp bolts before torquing. |
| Pass 2 — Final | 22 ft-lbs (30 Nm) | Replace bolts — torque-to-yield. Do not reuse. |
Related Fault Codes
Click any fault code to open the AI Diagnostic Engine for guided troubleshooting.
Frequently Asked Questions
What is the torque spec for Volvo/Mack MP8 injector hold-down bolts?
MP8 injector hold-down bolts torque to 22 ft-lbs (30 Nm) after an initial snug pass at 15 ft-lbs. Lubricate threads with clean engine oil.
Do MP8 injector bolts need to be replaced?
Yes — MP8 injector hold-down bolts are torque-to-yield and must be replaced every time they are removed.
What is the MP8 fuel rail pressure range?
The MP8 common rail system operates at up to 29,000 PSI. Proper injector sealing is critical at these pressures.
What fault codes are related to MP8 injector issues?
Common related fault codes include SPN 157 FMI 18 (fuel rail pressure low), SPN 651 FMI 5 (injector circuit open), and SPN 651 FMI 6 (injector circuit short).