Following are the effects of excessive lubrication -

1. Valve may be stuck up due to carbon deposit which cause later compression explosion.
2. loss of compressor efficiency due to sluggish action of valve.
3. loss of cooler efficiency due to deposition of oil on the cooling surface
4. Piston and piston ring will be carbonized
5. To prevent air bottle corrosion
6. Carbon may deposit on the main engine starting airline.
7. May cause explosion of starting airline.
8. Deposition of lubricants on the piston head reduces clearance volume