Hydraulic Torque Wrench Troubleshooting: What’s Wrong With My Wrench?

A hydraulic torque wrench that suddenly stops working right usually gives you a few clues. Oil on the outside points you in one direction. A pump that hits pressure while the wrench does nothing points somewhere else.

The sections below cover some of the problems we see most often and the first things worth checking before the tool is taken apart.

Oil Leaking From the Wrench

If hydraulic oil is showing up around the piston, body seam, or another sealed area while the pump is running, a damaged O-ring or seal is a likely cause.

Once a seal has failed, tightening something on the outside usually will not solve it. The wrench needs to be opened, inspected, and the damaged sealing components replaced.

If the tool is still under warranty or you are not comfortable servicing it, contact Winshaw before disassembly.

Pump Builds Pressure but the Wrench Does Not Move

When the pump reaches pressure almost immediately but the wrench stays still, check the quick-connect couplers.

A coupler can appear connected without opening internally enough to let oil pass through. Disconnect and reconnect the fittings by hand and make sure each one seats fully.

Look for bent, damaged, dirty, or badly worn couplers while you are there. A questionable quick-connect is easier to replace than to keep chasing through the rest of the hydraulic system.

Wrench Moves While the Pump Is Idling

If the wrench starts advancing when it should not, trace the hose connections from the pump all the way to the tool.

The advance and return sides may have been reversed. This can also happen when multiple hose sections are connected in a way that changes which line ends up feeding each port.

Make sure the pump’s advance line reaches the wrench’s advance port and the return line reaches the return port before operating the tool again.

Wrench Moves but the Hex Slips

If the piston is cycling normally but the wrench slips when load comes on, look at the drive segment.

A drive segment installed in the wrong orientation may allow the tool to move without properly driving the fastener.

Open the wrench head according to the manufacturer’s service procedure and check the segment position. While it is apart, inspect the segment and mating surfaces for damaged or badly worn areas.

Wrench Does Not Actuate at All

Before blaming the wrench, check whether the pump is actually sending pressure to it.

Look at the fluid level, hose condition, and pump output first. If the pump is not building pressure normally, the problem may be with the fluid, valve, relief system, or the pump itself rather than the wrench.

If the pump is working normally, check whether the wrench has enough capacity for the fastener being worked. A tool that has reached its torque limit may simply be undersized for the job.

For more on pump-fluid selection and maintenance, see best oil for your hydraulic torque wrench pump.

Piston Stops Before Completing the Stroke

A wrench can build pressure and still stop partway through the stroke without showing any oil outside the tool.

That can point to internal bypassing. Oil may be getting past a damaged piston seal or worn area inside the cylinder instead of continuing to drive the piston.

Finding that problem usually requires opening the wrench and inspecting the piston, seals, and cylinder surfaces. Any scored or damaged parts need to be addressed before the wrench goes back into service.

Quick Troubleshooting Checklist

Finding the Leak

• After the wrench cycles, fresh oil may show up at one seam while the rest of the body stays dry. That seam is the place to inspect for a worn seal or O-ring.
• Pump builds pressure but the wrench stays still: Check the quick-connects before opening anything up. A coupler can look connected and still fail to pass oil if it is not fully seated.
• Wrench starts moving while the pump is idle: Follow both hoses from the pump to the tool and make sure the advance and return lines have not been crossed.
• Piston moves but the wrench slips: Check the drive segment position and condition.
• Nothing moves: Verify pump pressure, fluid level, hose condition, and wrench capacity.
• Piston stops partway through the stroke: Internal bypassing may be occurring inside the wrench.

If you still cannot pin down the problem, especially on a tool that is under warranty, contact Winshaw before taking the wrench apart. Checking the hoses, couplers, pump, and connections first can save a lot of unnecessary teardown.