Fan troubleshooting
Lubricant leakage on fan housings: through the seal, the split and from the seat
Over-filling, worn seals and shafts, split-line leaks, blocked drains and the rust-coloured fluid that means fretting.
Through the seal
| Cause | What to do |
|---|---|
| Too much grease at the first fill or when regreasing | Use only the recommended quantity; a grease gun with a measured dose and a quantity-and-interval tool |
| Worn seal | Replace it with a seal material that resists wear and is compatible with the lubricant; consider an extra cover |
| Worn shaft under the seal lip | Repair the seat with a thin sleeve instead of regrinding |
| Excessive operating temperature | The lubricant thins and leaks: address the cause of the heat first |
| Seal not suited to a vertical shaft | Choose a seal designed for vertical use |
| Impeller sucking oil out of the housing | Reduce the pressure differential or use a seal with a vent hole; check the breather is not blocked |
Leakage at the split and end covers
- The mating surfaces of base and cap do not match: clean the split surfaces, apply sealant, and check that the numbers on cap and base match.
- Poor mounting: wrong end cover adjustment or bolt tightening.
- No drain hole for old grease or oil: drill evacuation holes if needed.
- Oil return pipe not working: check pipe sizes and slopes.
- Wrong flow of lubricant in the housing, or a housing built for grease but run on oil: seek advice on the housing and seal design.
Rust-coloured fluid at the bearing or housing seat
That is fretting corrosion. It comes from a loose or uneven fit (see the fit articles), from impeller unbalance and an insufficiently stiff base, or from the outer ring moving axially under shaft growth. Inspect the shaft seat and the housing bore, correct the fits, and make sure the housing is supported over its whole base and has the right bore geometry and surface finish.
Takeaway. Leakage is a symptom of heat, over-filling or worn parts at the seal. Fix the heat and the fill before replacing seals again.
Put it to work in the tool