D13/MP8 Cylinder Head Crack — Coolant Loss, Combustion Leak
The VOLVO-MACK-MP8-CYLINDER-HEAD-CRACK (Volvo/Mack D/MP Series) diesel fault code means: D13/MP8 Cylinder Head Crack — Coolant Loss, Combustion Leak. This is a critical severity code.
- Keep driving?
- No -- stop driving
- DIY difficulty
- advanced
- Estimated cost
- $6,000-$15,000
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Common Symptoms
- Coolant loss with no visible external leak
- White steam or sweet-smelling exhaust
- Bubbles in coolant expansion tank
- Heater blows cold intermittently
- Overheat warning after highway pull
- Possible misfire on affected cylinder
Probable Causes (Ranked by Likelihood)
- Cracked cylinder head at exhaust valve bridge (well-known D13/MP8 high-mileage failure, typically 600K+ miles) Very Likely
- Head gasket failure from repeated overheating Likely
- EGR cooler coolant leak masking as head crack (diagnose both) Likely
- Water pump failure causing localized overheat Possible
- Incorrect head bolt torque from prior service Less Likely
Step-by-Step Diagnostic Procedure
Pressure-test cooling system and note drop rate.
Combustion-gas test coolant (block test strips) — positive result indicates head/gasket leak.
Isolate EGR cooler by clamping lines and re-pressurize — if leak stops at the isolation, it is EGR cooler, not the head.
Pull injectors and borescope cylinder walls for coolant wash.
Crack-check head with dye penetrant after removal, focusing on exhaust valve bridges.
If head is cracked, remanufactured head replacement with new gaskets, bolts, and injector cups is the correct repair (typical $6K-$12K parts and labor).
Frequently Asked Questions
What does Volvo/Mack code MP8-CYLINDER-HEAD-CRACK mean?
Volvo/Mack code MP8-CYLINDER-HEAD-CRACK (D13/MP8 Cylinder Head Crack — Coolant Loss, Combustion Leak) is a critical-severity diagnostic trouble code set on D11/MP7, D13/MP8, and D16/MP10 diesel engines in Volvo VNL/VNR and Mack Anthem/Pinnacle/Granite/Titan trucks. It indicates a fault in the cylinder head system and should be read with Volvo Premium Tech Tool (PTT) or Mack Guided Diagnostics.
Can I drive a Volvo or Mack truck with code MP8-CYLINDER-HEAD-CRACK?
No — this fault typically triggers derate or forced engine shutdown countdown. Further operation risks engine damage or stranding. Repair before continuing service.
How much does it cost to fix Volvo/Mack code MP8-CYLINDER-HEAD-CRACK?
Typical repair falls in the range $6,000-$15,000. Sensor/wiring repairs are at the low end; EGR cooler, NOx sensor set, DEF pump, injector, or head work runs at the high end. Volvo PTT or Mack Guided Diagnostics is normally required for calibration and parameter programming.