| Day | What happened |
|---|---|
| Day 1 | Customer asked to quote a boom cylinder seal kit. After hearing the symptoms we gave the discrimination test: raise the boom, bring the stick to mid-position, then watch |
| Day 1 | Pure sink with no cross-talk = the main line isn't holding pressure → hold valve; if stick movement makes the boom rise/fall, that's internal cylinder leakage |
| Day 2 | Test result: pure sink, no cross-talk — hold valve confirmed. Valve kit matched by machine serial |
| Day 5 | Kit fitted; boom sank under 2 cm in one hour (within spec). Work resumed |
| Test / symptom | Conclusion | Fix |
|---|---|---|
| Pure sink, unaffected by other movements | Hold valve / pilot check valve leaking | Replace the check-valve kit (a few hundred) |
| Boom creeps when stick/swing moves | Internal cylinder leakage (oil crosses chambers) | Replace the cylinder seal kit |
| Sink plus oil weeping on the rod | External leak | Rod seal first — don't tear the cylinder down yet |
Test first, buy second — one shift of cylinder teardown labor costs more than the valve kit itself.
| Method | What you provide | Result |
|---|---|---|
| 1. Part number (fastest) | The part number / VOE number / CAT number — nothing else needed | Stock and price confirmed within minutes; 100% precise |
| 2. Model + serial number + year | e.g. EC210B + machine serial + year 2015 | The same model can have several versions — the serial number pins it down |
| 3. Photo of nameplate / old part | A clear photo of the machine nameplate, or the printed/stamped number on the old part | We verify fitment from the photo — our responsibility, not yours |
| 4. Fault description + replacement history | Briefly describe the symptom and whether/when this part was replaced before | We help judge what to replace — and whether a root cause is still hiding |
Send any one of the four to our online chat to lock in the right part. The more you share, the faster and more accurate the quote.
Tap through to our live parts search — check stock and send us the part number for an instant quote:
Yes — it's observation only, no teardown. Raise, support and watch per normal procedure; we'll guide you step by step in text.
Similar job (holding pressure against sink), but names and mounting differ by machine — send the serial and we'll supply the right one.
Good idea — older machines need one sooner or later. Kits are matched by bore + part number; send both and we'll log them on your spares list.
Send it to our online chat — in-stock parts quoted the same day.