* Worn cylinder walls: The cylinder walls have worn down, allowing excessive piston movement.
* Scored cylinder walls: Deep scratches or gouges in the cylinder walls.
* Worn piston rings: The piston rings, which seal the combustion chamber, are worn and no longer provide a tight seal. This contributes to a loose feeling, though the piston itself might not be *loose* in the cylinder. It's more a case of a lack of seal.
* Damaged piston: The piston itself might be damaged (cracked or severely worn).
Repair options (in order of increasing cost and invasiveness):
1. (If only worn rings): Piston ring replacement: This is the *least* invasive option. It involves removing the cylinder head, pistons, and replacing the piston rings. This is a significant job requiring engine disassembly, but it's much less expensive than a rebuild. This only works if the cylinder walls are still within spec.
2. Engine Rebore and Oversize Pistons: If the cylinder walls are worn beyond specification, they need to be rebored (machined to a larger diameter). Then, oversized pistons are installed to maintain the proper fit. This requires professional machine shop work.
3. Engine Replacement: If the damage is extensive (multiple cylinders, cracked pistons, etc.), a full engine rebuild might not be cost-effective. Replacing the entire engine might be a more practical solution.
You cannot effectively repair this yourself unless you have extensive engine rebuilding experience and the proper tools. The work involved requires specialized tools, precision measurements, and a clean working environment.
What you should do:
1. Don't try to run the engine: Continuing to run the engine with a loose piston will cause catastrophic damage, potentially destroying the entire engine.
2. Diagnose the problem accurately: Get a proper diagnosis from a qualified mechanic. They'll need to inspect the engine to determine the extent of the damage.
3. Get a repair estimate: Get quotes from several reputable mechanics or engine rebuild shops for the repair options listed above.
4. Make a decision based on cost and vehicle value: Weigh the cost of repair against the value of your vehicle. If the repair costs are more than the car is worth, engine replacement or selling the vehicle might be the best choice.
In short, a "loose piston" is a serious problem that requires professional attention. Attempting a DIY repair is likely to lead to further damage and greater expense.
