Intake manifold corrosion may lead to an exhaust gas leak, damage to the fuel return line which could cause a fuel leak, and heat damage to the insulation at the fire wall.

The intake manifolds may have corroded. A chemical reaction involving sulfur in the diesel fuel that takes place under certain conditions can lead to the formation of sulfuric acid in the exhaust channel of the intake manifold.

What to do: Book it in at your next service. There is no deadline and no charge.