1. Worn Valve Stem Seals: Over time, valve stem seals can become worn and brittle, leading to insufficient sealing between the valve stems and the valve guides. As a result, oil can seep past the seals and enter the combustion chamber, resulting in smoke on startup.
2. Oil Control Rings: The piston oil control rings are responsible for controlling the amount of oil that is used for cylinder lubrication. If the oil control rings are worn, damaged, or clogged, oil can bypass the rings and end up in the combustion chamber.
3. Piston Rings: Worn piston rings can also cause oil consumption. The gaps between the piston rings can become excessive over time, allowing oil to get into the combustion chamber.
4. PCV System Issues: The Positive Crankcase Ventilation (PCV) system helps control crankcase pressure and regulate oil vapors. A clogged or malfunctioning PCV valve can cause pressure build-up in the crankcase, leading to excessive oil burn-off through the exhaust.
5. Worn Turbocharger Seals: If your 1993 Probe 2LT is turbocharged, worn turbocharger seals can allow oil to leak into the exhaust system, resulting in smoke on startup.
6. Excessive Blowby: When piston rings are worn and sealing between the cylinder walls and the pistons becomes compromised, excessive blowby occurs. This allows combustion gases and unburned fuel vapor to escape into the crankcase, increasing oil pressure and potentially leading to oil burning.
7. Damaged Head Gasket: A damaged or blown head gasket can provide an unintended pathway for oil to enter the combustion chamber. This can occur if the gasket fails or if there's a breach between the cylinder and coolant passages.
It's important to have the root cause correctly diagnosed and addressed by a qualified mechanic. This may involve engine inspection, oil consumption tests, compression tests, and repair or replacement of faulty components as needed.
