An LMM PCV reroute fix is a simple crankcase ventilation modification for 2007.5–2010 6.6L Duramax diesel trucks. It is designed to reduce oil vapor buildup in the intake system by redirecting crankcase gases away from the turbo inlet and intercooler piping.

On the factory LMM setup, the PCV (positive crankcase ventilation) system routes oil mist back into the intake. Over time, this can leave residue inside the turbo, boost pipes, and intercooler, which affects cleanliness and long-term efficiency.

What Is an LMM PCV Reroute Fix?

An LMM PCV reroute fix changes how crankcase pressure is vented. Instead of sending oil vapor into the intake system, it is redirected through a hose or vent system away from the turbo inlet.

Common setups include:

• Simple hose reroute to frame rail
• Block-off cap for intake port
• Tee fittings with extended vent line
• Optional catch can installation

This modification helps separate oil vapor from intake airflow.

Why the Factory PCV System Needs a Fix

In the stock LMM Duramax design, crankcase gases are drawn into the intake to be burned again. While this is normal for emissions control, it can cause:

• Oil buildup in intercooler piping
• Turbo inlet contamination
• Intake manifold sludge over time
• Reduced airflow efficiency
• Messy engine bay residue

These issues become more noticeable on higher-mileage trucks or lightly tuned engines.