How to Check for a Bad Gear on a Hydraulic Pump
Hydraulic gear pumps, also known as positive displacement pumps, are found wherever hydraulic systems are used. The two hydraulic gear pump types are internal and external -- located either inside or outside an engine -- as gear-driven hydraulic pumps operate on engine-supplied power. Hydraulic pumps are found in combustion engines, hydraulic equipment and anywhere an engine-driven pump is required. Does this Spark an idea?
Things You'll Need
- Wrench set
- Screwdriver
- Metal straightedge
- Feeler gauges
- Clean rag
- Cleaning solvent
- Air compressor
- Replacement gasket
- Petroleum jelly
Instructions
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1
Disassemble the hydraulic pump. Depending on the positive displacement pump's setup, the bolts to disassemble it are typically found in either of two areas: on the side of outside pumps or on the bottom of inside pumps -- such as those used for automotive oil.
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2
Remove the old gasket by scraping it with a screwdriver. Wipe off the gears and any other excess fluid on the pump. A clean surface makes measuring clearances easier.
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3
Measure the clearance between the pump's housing cover and the gears. Place a straightedge -- edges up and down -- over the entire opening, including the housing. Make sure the gears are fully inserted in the pump. Place feeler gauges between the gears and the straightedge until the correct measurement is determined.
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4
Check the clearance between the pump body and gear teeth. Place feeler gauges between the gear teeth and pump housing, in various locations, until the clearance between the two is determined.
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5
Clean the entire pump before reassembly. Take the gears out and wash them in cleaning solvent, along with all other parts, including the pump housing. Blow everything dry using an air compressor to prevent contamination. Apply petroleum jelly to all inside surfaces, including the gears. Put the pump assembly back together by inserting the gears, placing the new gasket on the housing, and bolting the cover back on.
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6
Install and prime the hydraulic pump according to the manufacturer's directions.
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Tips & Warnings
Normal clearances between the gear teeth and pump housing should be between .001 to .004-inches. The gears need to be replaced, if the measurement is over .005-inches. The gear/cover clearance should be between .001 to .005-inches. Check the specifications of your particular pump for exact clearances.
References
- The Engineering Toolbox: Positive Displacement Pumps
- AutoMedia: Oil Pump Restoration; Len Emanuelson
- The Pump School: External Gear Pumps
- The Pump School: Internal Gear Pump Overview
- Intertech Publishing Corporation: Large Diesel Service Manual
Resources
- Photo Credit Jupiterimages/Photos.com/Getty Images
