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Transmission Troubleshooting FAQ – Construction & Heavy Equipment

General Help

Q: How do I get technical support for Centranz transmissions?
A: Call 1-816-650-3161 and ask for Mike for direct troubleshooting assistance.

Common Transmission Problems

Slipping Transmission

Q: Why is my construction equipment transmission slipping?
A: Common causes include:

  • Low or incorrect oil level

  • Wrong oil grade

  • Weak or broken pressure regulating valve spring

  • Restricted pump suction screen

  • Low pump output (wear or damage)

  • Internal clutch leaks or worn disks

Machine Will Not Move

Q: Why won’t my machine move when the engine runs?
A: Possible issues:

  • No or low transmission pressure

  • Service or park brakes engaged

  • Shift linkage or control valve stuck

  • Faulty torque converter

  • Broken shafts, gears, or differential parts

Low Transmission Pressure (All Gears)

Q: Why is transmission system pressure low in every gear?
A: Likely reasons:

  • Low fluid level

  • Plugged suction strainer

  • Faulty pressure regulating valve

  • Gasket leaks in control valve

  • Pump wear or failure

Low Pressure in Specific Gears

Q: Why is transmission pressure only low in one or two gears?
A: Causes include:

  • Blown gasket in the control valve

  • Clutch piston or seal leakage

Slow Shifting

Q: What causes slow transmission shifting in heavy equipment?
A: Check for:

  • Low or aerated oil

  • Low system pressure

  • Restricted suction line

  • Internal leakage

  • Sticking clutch cut-off valve

Harsh or Fast Shifting

Q: Why does my transmission shift too fast or harshly?
A: Possible problems:

  • Excessive system pressure

  • Stuck modulation valve

  • Faulty check valves

  • Broken piston return spring

Creep in Neutral

Q: Why does my equipment creep forward or backward in neutral?
A: Usually caused by warped clutch disks or plates.

Transmission Overheating

Q: Why is my transmission hydraulic system overheating?
A: Causes include:

  • Low or incorrect oil level

  • Wrong oil grade

  • Park brake engaged

  • Restricted or leaking lube lines

  • Blocked cooler airflow

  • Faulty thermal bypass valve

  • Warped plates causing drag

  • Internal hydraulic leaks

  • Low pump output

Excessive Transmission Noise

Q: What causes loud transmission noise under load or no load?
A: Possible sources:

  • Low idle speed

  • Worn or damaged internal parts

  • Low lubrication pressure

  • Wrong or overfilled oil

  • Air leak on suction side of pump

Transmission Vibration

Q: Why is my transmission vibrating?
A: Most often caused by:

  • Aerated oil

  • Failed universal joints

Loss of Power or Poor Acceleration

Q: Why does my heavy equipment lack power or acceleration?
A: Common issues:

  • Engine fast idle set incorrectly

  • Wrong oil type

  • Aerated fluid

  • Low transmission pressure

  • Warped clutch plates

  • Brake drag

  • Sticking clutch cut-off valve

  • Engine underperforming

Torque Converter Problems

High Stall RPM

Q: Why is torque converter stall RPM too high?
A: Causes include:

  • Aerated oil (bubbles visible in bypass)

  • Converter relief valve stuck open

  • Seal leakage

  • Internal torque converter damage

Low Stall RPM

Q: Why is torque converter stall RPM too low?
A: Typically due to:

  • Low engine power

  • Internal torque converter failure