Why is the hydraulic pump hot and not strong?

EP.18 Symptoms "Hot Hydraulic Pump Gear Then No Force"

It is a common problem in hydraulics, mainly due to the pump itself, the oil, and the external system.

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🔧 1. Gear Pump has deteriorated.

When the pump is hot and then the pressure falls, often indicating more internal parts expanding or leaking inside, e.g.

Gear and pump feel causes Internal Leakage

Front-Rear Cover (End Plate) Feel Not Close To Sprocket

Bearing / Bushing is loose, allowing the indentation gear to leak back oil.

When hot, oil viscosity decreases → more internal leakage → pressure drop. No force.

👉 How to check:

The pressure is measured while cold and while hot (the pressure is reduced by more than 15-20%, indicating an internal leakage pump).

Listen to the unusual sound or vibration of the pump.

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🛢️ 2.Hydraulic oil is too hot / properties are not suitable

Too hot oil (> 60-70 ° C) → Reduced viscosity → More internal leakage

Use oil too lightly (e.g. ISO 32 in systems where ISO 46 or 68 should be used)

Air Mixed bubbles from intake or filter

👉 Results:

Pressure drop

Unusual hot pump

A loud "howling" or "loud fasting" sound from the cavitation.

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⚙️ 3. External systems have problems.

Relief Valve Leak or Overpressure

External load is too heavy or the motor drives the cycle pump too low.

Oil cooler does not work / clog, causing heat to accumulate

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🧰 4. Preliminary solution

1.Oil temperature check (should not exceed 60 ° C)

2. Measure evening pressure and hot episodes. Compare

3. Leak detection around pump, valve and pipe

4. Check the Suction Filter if it is clogged or not.

5. If the pressure falls when hot → should be replaced or overholed the pump gear.

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If you have more information, such as

Brand / Model of Pump

Pressure applied (bar or PSI)

Estimated oil temperature

I can help you to analyze exactly what part of the problem is (such as degenerative pumps or unsuitable oils).

Great. 👍

This table is an industrial technician used to analyze the symptoms of "hot hydraulic pump gear and no force."

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🧭 Symptom Analysis Table - Causes - How to Fix It

Symptoms: Hot pump gear and pressure drop / no lift.

Sequence, symptoms found, possible causes, how to check, how to fix

1 Fast hot pump, pressure drop when hot, pump internal parts (sprocket, lid, bushing) feel or leak inside, measure evening and hot episode pressure, compare (if fall > 15-20% is leaky pump), change or overhole pump gear

2 Pumps are noisy, "howling" or "sucking air," suction pipe leak / suction side seal leak air intake / suction filter ton. Use oil on the suction joint while walking the system. If the sound is reduced, it indicates that the leak sucks, tighten the joint, change the O-ring / seal, and wash or change the suction filter.

3. Oil is extremely hot all the time. Poor cooling system (no oil cooler or clog). Oil temperature measurement (should not exceed 60 ° C). Wash / replace oil cooler, increase ventilation.

4 Pressure is not up to the set value. Relief Valve is leaky or overadjusted. The pressure is measured when the load is closed. If it is much lower than the set, the valve is leaky. Remove or replace Relief Valve.

5 Hot pump but pressure is still available. Use oil too light (e.g. ISO 32 in the system should use ISO 46 / 68). Check the oil type from the oil tank. Change to oil where the viscosity fits the cycle specification and pressure.

6 Unusually hot pump when running long time. Low cycle drive motor or not enough torque. Check the motor cycle with a cycle meter. Check the voltage / motor cycle according to the specification.

7. Intermittent force pump with air bubbles in the oil (Cavitation / Aeration). Look at the oil level. If there are bubbles or turquoise, add enough oil. Change the filter. Wash the tank.

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📌 Summary of preliminary guidelines

1.Measuring evening pressure - hot episodes

→ If fall more than 20% degenerative pump

2. Measure the oil temperature in the tank.

→ Exceeding 60 ° C indicates poor cooling system

3. Listen to the suction sound / suction filter.

→ If there is a sound, "howling" or "loud fasting" is cavitation.

4. Relief Valve and precursor pressure check

→ Be sure not to leak or adjust too low

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When my friends come here, I hope to provide you with the information to maintain your friends' hydraulic systems for a longer life, no damage often, or if damage occurs, correct it in a timely manner.

Vitek Hydraulic Pump Repair Center Service 🧑‍🔧🔧🔧

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