Here's a breakdown of how to approach fixing engine blowby:
1. Diagnose the Cause:
This is the most important step. Blowby isn't a disease; it's a symptom. Possible causes include:
* Worn Piston Rings: This is the most common cause. Rings wear down over time, losing their ability to seal the combustion chamber.
* Worn Cylinder Walls: Scratches, scoring, or excessive wear on the cylinder walls prevent a good seal with the piston rings.
* Damaged or Worn Pistons: Damaged pistons can compromise the seal.
* Valve Guide Wear: Excessive wear on valve guides can allow combustion gases to escape past the valves.
* Blown Head Gasket: A failing head gasket can allow combustion gases to leak into the cooling system or crankcase. This often manifests as milky oil or pressure in the cooling system.
* PCV (Positive Crankcase Ventilation) System Problems: A clogged or malfunctioning PCV system can increase crankcase pressure, leading to more blowby. This is less about actual gas escaping past the rings, and more about pressure build-up.
2. Methods to Address the Underlying Problem (Requires Mechanical Expertise):
The solutions are generally extensive engine repairs, requiring considerable mechanical knowledge and tools. These are *not* DIY tasks for most people unless you have significant experience:
* Engine Overhaul: For worn piston rings, cylinder walls, or pistons, a complete engine overhaul is often necessary. This involves removing the engine, disassembling it, replacing or re-ringing the pistons, honing or replacing cylinders, and reassembling the engine.
* Cylinder Honing/Sleeving: If the cylinder walls are scored or worn, honing (lightly smoothing the surface) or sleeving (installing new liners) might be possible.
* Piston Ring Replacement: Replacing just the piston rings is a less extensive repair than a full overhaul, but still requires engine disassembly.
* Head Gasket Replacement: If the head gasket is blown, it needs to be replaced. This also requires engine disassembly to access the head.
* Valve Guide Replacement: If valve guide wear is the culprit, replacing the guides requires specialized tools and knowledge.
* PCV System Repair/Replacement: Clean or replace the PCV valve and associated hoses. This is often a relatively straightforward repair.
3. Things to check BEFORE jumping to major repairs:
* Oil Level: Check your oil level regularly. Excessive blowby can cause the oil level to increase as it mixes with combustion byproducts. However, a high oil level alone doesn't diagnose the problem.
* Oil Condition: Check the color and consistency of your oil. Milky oil can indicate a blown head gasket.
* PCV System Inspection: Inspect the PCV valve and hoses for clogs or damage. A clogged PCV system can worsen the apparent blowby. This is a much easier and cheaper fix than an engine overhaul.
Important Note: Engine blowby is a serious issue. Continuing to drive a vehicle with significant blowby can cause catastrophic engine failure. If you suspect blowby, consult a qualified mechanic for proper diagnosis and repair. Attempting major engine repairs without the necessary skills and tools can cause more damage and cost significantly more in the long run.
