A customer asked us to fit an engine into a Liebherr L564 wheel loader. We installed the engine, but when it came to fitting the hydraulics it turned out that the entire pump set had been removed and left unprotected in the grass and mud. You cannot simply bolt something like that back onto a machine, so the loader came to our workshop and the hydraulics went for inspection.

Inspecting the pump set

The set consisted of three pumps – A10, A11 and A4 – plus the pump drive gearbox. After an initial wash we dismantled them one by one, always starting with the regulator and controller so they would not get in the way or be damaged.

A10 – full of oil inside, fortunately with no sign of water. Bearing shells to replace; the remaining parts (cylinder barrel, valve plate, pistons) to be ground and lapped.
A11 – no major damage: grinding and lapping, plus the standard full seal kit.
A4 – plate and cylinder in good condition, light rust on the control piston that could be removed. The pistons were leak-tested.
Pump drive gearbox – the cover O-ring was corroded and overheated and had to be replaced; the gears were in good condition, so washing, new seals and a new shaft seal were enough.

Despite the poor storage conditions the pumps turned out to be in good shape. Worn parts were replaced with new ones, and those fit for further service were lapped and ground.

Assembly and testing

During assembly every rotating group is wetted with oil so it never runs dry, and the bearings are greased. The separator bracket bolts are fitted with thread locker, shafts are secured with circlips, and new shaft seals are fitted. Each pump was tested on our dyno after assembly, then the complete set was bolted to the gearbox and installed in the machine together with the hydraulic lines.

Start-up and road test

So in this 24-tonne loader we overhauled both the diesel engine and the power hydraulics – both tested on the dyno beforehand. After start-up we fixed a few leaks and replaced a throttle cable that had seized with age. Before the road test we also checked the air filter – something customers often forget, yet a rebuilt engine needs clean air, and the filter housing must be airtight.

The loader drives, steers and brakes, and the attachments work smoothly. Before handover the machine undergoes longer real-world testing, including with the hydraulics fully warmed up.

Takeaways

Removed hydraulic components must be protected – plug the ports and store them under cover. Water and dirt in a pump are a direct route to an expensive repair.
Before fitting pumps that have been lying outside a machine for a long time, it is always worth having them inspected.
Separate dyno tests for the engine and hydraulics, followed by a test of the whole machine, allow it to be handed over without surprises.

See our services: hydraulic pump and motor repairs, combustion engine overhauls and construction machinery service.

Watch the repair video: How Did a Simple Engine Installation Turn Into a Full Hydraulic Overhaul? Liebherr L564