Here's why:
* Head Gasket Failure: This is the most likely culprit. A blown head gasket allows coolant to leak into the cylinders. The increased pressure at higher RPMs forces more coolant into the combustion chamber, resulting in more smoke.
* Cracked Cylinder Head: A crack in the cylinder head can also allow coolant to mix with combustion gases. Similar to a head gasket failure, you'll see more smoke under higher load.
* Cracked Engine Block: Less common, but a crack in the engine block can also lead to coolant leakage into the cylinders.
* Coolant Leak into Intake Manifold: While less likely to cause significant white smoke, a leak into the intake manifold (perhaps a cracked manifold or a faulty intake gasket) can introduce coolant vapor into the combustion process.
Why more smoke at higher RPMs?
At higher engine speeds, the increased pressure within the cylinders forces more coolant into the combustion chamber, leading to more pronounced smoke.
What to do:
* Do NOT continue driving the vehicle. Driving with coolant in the cylinders can cause severe damage, including hydro-locking (where the liquid coolant prevents the piston from moving) which can bend or break connecting rods.
* Check your coolant level. You'll likely find it low.
* Inspect the engine for external coolant leaks. Look for obvious signs of leaks around the head gasket, cylinder head, and engine block.
* Have a mechanic diagnose the problem. They can perform a compression test, leak-down test, and other diagnostic procedures to pinpoint the source of the leak. Ignoring this could lead to a very expensive engine repair or replacement.
White smoke is a serious indicator. Immediate action is crucial to prevent further damage to your engine.
