Temperatures and Pressures to be Checked
We have seen how important lubricating oil is to an engine;
- Reducing friction.
- Preventing damage to moving parts.
- Dissipating excess heat.
It is imperative to keep the oil viscous and in good condition. This is carried out by the watch-keeping engineer who is responsible for maintaining a proficient engine-room watch especially, on lube-oil temperature and pressure, but also on the condition of the oil.
The diesel combustion process produces acids/sulphur residues; these in turn can escape between the piston rings and cylinder liners, getting scraped of with excess oil by the oil ring, thus making their way to the sump. This will contaminate the oil, degrading it to such an extent that it will require changing.
Also inherent of the marine diesel engine is cooling water leaking from the jackets due to a worn or damaged rubber seal ring between the cylinder liner landing and the engine block. The jacket cooling water will leak down the engine block, dripping unimpeded right into the lube oil sump. Watch keepers need to be aware of this and check the 'tell tale leak detecter' also that the sump oil has not become emusified two or three times a watch, using the dip-stick whilst checking for water in filters and centrifuge outlet.
We must also remember that not only should we depend on instruments to show us various temperatures and pressures but also to rely on our own sense of touch and smell is equally important, whether this is carried out by lightly touching the sides of the crank-case doors with the back of a hand, gripping the lube-oil supply pipes or by examination of the oil itself whilst rubbing a sample of it from the sump dipstick between the fingers when checking oil levels.
Maintenance is also important, oil must be changed regularly, the optimum differential pressure before and after the filters must be maintained and the filters cleaned as required. Any particles of white metal, dirt or water in the filters should be investigated immediately.
Most engines now have in-line lube-oil centrifuge system that will extract particles of dirt and moisture from the oil, helping to preserve the oils inherent properties.
A ship's engine-room is a dangerous place to work, conceivably the most essential duty of the watch-keeping engineer is to sustain a constant lube oil temperature and pressure vigil, so that any rise in oil temperature or fall in oil pressure or a change in the condition of the oil is fully investigated by him.These conditions can be symptomatic of a bearing or other engine component running hot, and along with an oily mist detector alarm sounding can indicate an imminent serious explosion in the crankcase.