0100:00
Identity and cold state
Show the complete machine, product plate, model suffix, serial number and monitor. Film the block or coolant reading before touching the key; state ambient temperature and time.
Used Excavator Cold Start Video Inspection Protocol
Remote-buying video protocol
Used Excavator Cold Start Video Inspection Protocol
A cold-start video is useful only when it proves the engine was cold, keeps one continuous take from identity to first ignition, and finishes with a hot hydraulic test. A ten-second smoke clip is not enough.
Direct answer
Request one continuous 12-18 minute recording: identity and temperature before start, the first crank without cuts, 90 seconds of exhaust and engine, controlled warm-up, hydraulics, travel, swing, load and a hot restart. If the seller cannot prove the cold condition or cuts across the first start, grade the evidence incomplete.
The eight-scene recording you should receive
0201:00
Pre-start walk-around
With the engine off, show the ground below the engine and pumps, visible levels, radiator, hoses, cylinders and exhaust. Do not clean leaks between scenes.
0303:00
Key-on evidence
Record warning lamps, fuel level, displayed hours and temperature. Keep original sound and enough focus to read the monitor.
0403:30
First crank
Use one take from key movement to stable idle. Record crank duration, throttle input, booster use and whether the engine stalls.
0504:00
First 90 seconds
Alternate exhaust and engine views without cutting. Watch persistent smoke, knock, blow-by, new leaks and idle stability.
0606:00
Controlled warm-up
Increase rpm gradually. Cycle boom, arm, bucket, swing and travel without sending cold oil immediately to maximum load.
0710:00
Hot load test
Compare speed and smoothness, safely hold the attachment, test both tracks and swing, and record the final monitor temperature.
0815:00
Restart and second walk
Shut down, wait two minutes, restart, then revisit the ground, seals, pumps, connections and coolant. Finish by showing serial and hours again.
Smoke colour is a clue, not a diagnosis
| Signal | Comparison | Decision |
|---|---|---|
| Brief white vapour | It may be condensation in cool air and should reduce as combustion stabilises. | Compare duration, smell and temperature. If it clears promptly and idle becomes even, continue inspection. |
| Persistent white | It can relate to unburned fuel, low compression, injection or coolant entry. | Pause the purchase decision and request compression, fuel-system and cooling-system checks. |
| Blue or blue-grey | It suggests oil consumption through turbo, guides, rings or ventilation, but video cannot isolate the cause. | Do not pay a low-hour premium without a hot test, oil-level record and further diagnosis. |
| Black under light load | It can indicate excess fuel, restricted air, turbo or injector issues; one brief puff at heavy load is not the same as continuous smoke. | Compare no-load and loaded behaviour. Persistent smoke requires diagnosis and a repair allowance. |
Decision after the video
Proceed
Continuous take, readable identity, reasonable crank, clearing smoke, no alarms or fresh leaks, and consistent hot performance.
Move to physical inspection, undercarriage measurement and documents.Request evidence
Cold state not proved, weak audio, missing monitor or serial, idle-only test, edited clip or already-warm machine.
Repeat the missing scenes before reserving.Stop
Heavy knock, abnormal pressure or temperature, persistent smoke, immediate cooling pressure, fluid mixing, active leak or stalling under load.
Obtain in-person diagnosis and repair cost before negotiation.Four ways a video can mislead without being fake
- The machine was warmed before filming and only a restart was recorded.
- Phone processing suppresses noise and changes smoke colour; preserve original audio and use side light.
- A front-only view hides the pump and exhaust sides; require both sides.
- An engine can start cleanly while hot hydraulic oil later reveals lost performance; the second half is mandatory.
Technical basis and limits
-
01Caterpillar: daily mini excavator inspection guide
Manufacturer guidance supports the sequence; smoke and sound remain screening observations, not a remote diagnosis.
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02Komatsu: technical and field services
Manufacturer guidance supports the sequence; smoke and sound remain screening observations, not a remote diagnosis.
Complete the inspection
Cold-start video questions
How long should the video be?
Twelve to eighteen minutes usually covers identity, start, warm-up and hot testing. Continuity matters more than an exact duration.
Can white smoke be normal?
Yes. Brief vapour may be condensation. Persistent white smoke with odour, rough running or coolant loss requires diagnosis.
Does a fast start prove a healthy engine?
No. It proves one condition only. Compare pressure, temperature, blow-by, noise, smoke, hydraulic load and hot restart.
Should I request an infrared thermometer?
It helps document temperature differences but does not replace the continuous take or system reading. Measure several points and record ambient conditions.
Why test hydraulics hot?
Warm oil can reveal slow response, drift, noise and leakage hidden when cold. It is the critical comparison before quotation.
What if the seller sends only short clips?
Treat them as sales material rather than complete evidence. Send this storyboard and request a new serial-linked continuous take.
Published and reviewed: 19 August 2026 · YUANJIAN MACHINERY INTERNATIONAL TRADING LIMITED