HO Livesteam loco

[Rob1962]

The HO Livesteam Loco ran great for 15 minutes on a brand new 12x5 layout.The next run, the loco took off, then 20 seconds later came to a complete stop. Then I would let it Sit for 10 seconds. It took off very fast, then the loco stopped again. Then again, pressure built up, and when pressure drops, it starts again. Any clues to what this might be? BTW, this is a 2-cylinder oscillator.

 

[Paul M]

Something jamming, or leaking, or loose?

 

[GAP]

I pasted your post into ChatGPT and this is what it returned.

Thanks for the detailed description — that helps a lot. Based on your explanation, here's a breakdown of what's likely going on with your HO live steam locomotive:

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• First run: Perfect for 15 minutes.
• Second run: Starts strong, then stops after ~20 seconds.
• Wait ~10 seconds: pressure rebuilds → Loco takes off again briefly.
• Cycle repeats.
• It's a 2-cylinder oscillator loco.

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Your symptoms strongly suggest that steam is not flowing consistently to the cylinders, or that condensate (water) is building up in the cylinders, causing them to "hydro-lock" temporarily. When the pressure builds up again, it forces the loco to run briefly until it locks again.

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1.​

• If the burner isn’t producing enough consistent heat (e.g., bad fuel flow or cooling too fast), pressure will drop quickly under load.
• Check: Burner flame color (should be blue and strong), consistent fuel feed, and tank venting.

Fix: Make sure the burner is clean, the fuel is fresh, and there's good airflow around the flame. Also check for any blockages in the jet or nozzle.

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2.​

• Oscillating cylinder locos are especially prone to this.
• As the steam condenses inside the cold cylinders, water can accumulate and stop piston movement.
• After a brief pause, the steam pressure overcomes the water until it builds again.

Fix:

• Warm up the cylinders more gradually before running at full throttle.
• You may need to install (or open) any drain cocks if your model has them — some HO-scale oscillators don’t.
• Slightly "crack" the throttle and let it warm up for 30–60 seconds before running fast.

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3. ​

• Once things heat up, thermal expansion might cause the piston or rod to stick slightly.
• Could also be a lubrication issue.

Fix:

• Apply high-temperature steam oil to all moving parts.
• Check for any binding or tight spots in the motion once the engine is hot.

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4.​

• If the safety valve is releasing steam too early, you won’t maintain enough working pressure.
• But usually this would be audible.

Check: Is the safety valve "popping" during the run? If yes, it might be opening too early.

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1. Run without the loco on the track:
   
   • Let it steam up and observe if pressure builds and drops while in place.
   • Listen for any escaping steam, odd noises, or leaks.
2. Turn the wheels gently by hand while hot:
   
   • Resistance or binding may point to mechanical expansion problems.
3. Check the exhaust steam:
   
   • Is there a lot of water spraying out? That indicates condensation issues.
4. Compare with cold vs. hot behavior:
   
   • If the loco runs fine cold but starts struggling once fully hot, it's probably a thermal or lubrication issue.

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️ Summary of Fixes to Try First:​

• Let the engine warm up longer before running.
• Make sure you're using proper live steam cylinder oil (not regular model lube).
• Check for water buildup (condensation).
• Ensure the burner is producing consistent heat and not sputtering out.
• Lightly oil moving parts.
• Watch the pressure gauge if you have one (or note steam production changes).

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