Lubrication science
Lubrication problem solving: symptoms, causes and a seven-step method
Quick answer
A quick reference for eight common lubrication problems, and a step-by-step approach that finds the real cause.
Problems, causes and fixes
| Problem | Common causes | What to do |
|---|---|---|
| Too little lubricant | Low level, leaks, blocked lines or filters | Top up, fix leaks, clear or replace filters |
| Contaminated lubricant | Ingress of dirt or water, failed breather, poor storage | Change oil, improve sealing and handling |
| Oxidation or degradation | High temperature, long interval, poor-quality oil | Change oil, improve cooling, use an oxidation-resistant oil |
| Wrong viscosity | Wrong grade, temperature change, shear | Use the correct grade and check operating temperature |
| Foaming | Air entering, high agitation, contamination, wrong level | Check the level, reduce agitation, eliminate contamination |
| Excessive wear | Poor lubrication, contamination, misalignment, overload | Improve lubrication, clean the system, correct alignment |
| Rust and corrosion | Water, acidic by-products, too little inhibitor | Remove water, change oil, keep the system dry |
| Overheating | Low level, blocked cooler or line, too much load, too much oil | Correct level, clean cooler, check load |
Seven-step method
| Step | What to do |
|---|---|
| 1. Identify | Note symptoms and gather information. |
| 2. Analyse | List possible causes from the data and inspection. |
| 3. Isolate | Narrow to the most likely cause. |
| 4. Test | Confirm the cause by measurement. |
| 5. Correct | Apply the fix. |
| 6. Verify | Check the problem is gone and the system is normal. |
| 7. Prevent | Change the practice, schedule or design so it does not come back. |
Quick symptom guide
| Symptom | What it suggests | Check |
|---|---|---|
| Dark or dirty oil | Contamination or oxidation | Filters, seals, breather, oil analysis |
| High temperature | Low level, blocked cooler, overload | Oil level, cooler, load |
| Foam | Air in the oil, wrong level | Oil level, return line, suction line |
| High wear metals | Excessive wear | Source of the metal, alignment, load |
| Water in oil | Seal failure or condensation | Seals, breathers, storage |
| High viscosity change | Oxidation or wrong oil | Oil type, temperature |
| Oil leakage | Seal wear, loose fittings | Seals, gaskets, connections |
Warning signs: act early
- A sudden rise in operating temperature.
- Unusual noise or vibration.
- A quick drop in oil level.
- Burnt smell or discoloured oil.
- Filters that block often.
- Foaming or aerated oil.
Root cause tools
- Five whys: keep asking why until you reach the cause you can change.
- Fishbone diagram: group causes by method, material, machine and people.
- Pareto analysis: find the few causes behind most of the problems.
- Change analysis: ask what changed before the problem began.
Takeaway. Fix the cause, not the symptom. Use a fixed method, confirm with a measurement, and change the practice so the problem does not return.
Put it to work in the tool