Volvo L70D (2001) Third & Fourth Valve “Detent” Discussion

[MikePhua]

Machine Background
The Volvo L70D is a mid-size wheel loader produced in the early 2000s. According to Volvo’s specs, it has a gross engine output of 94 kW (128 hp), load‑sensing working hydraulics, and a torque‑parallel lift linkage.  Its hydraulic pump capacity is about 42 gpm (160 l/min), with system relief pressure around 3770 psi.

Problem Description
A user asked if there’s any way to lock or “detent” the 3rd or 4th hydraulic valve on their 2001 L70D. The context: they’re using a brush‑broom attachment and want the hydraulic flow to stay on continuously, so they don't have to hold down the lever while the broom spins. On their loader, the lift and curl (standard loader functions) are held by magnets and proximity sensors, but it's unclear how to do something similar for the 3rd or 4th function.

Suggested Solution by Experienced Mechanics

• One mechanic noted that the servo valve blocks are identical for the main functions. You could potentially install a magnet (solenoid) and plate for a “return‑to‑dig”‑style detent on the pilot lever.
  
• He strongly recommended wiring this into an emergency stop (e-stop) mounted on a visible location (like the A-pillar). The idea is: when the magnet holds the lever in place, you also have a big red “kill” button you can hit if something goes wrong, rather than trying to manually override the magnet.
  
• According to another contributor, there used to be a Volvo factory kit (catalog number 80098) that provided a “constant-on” detent for the 3rd function. Whether all parts are still available is uncertain.
  

Challenges & Aftermarket Reality

• The OP contacted Volvo and was told that the magnets for this purpose are no longer available (“NLA”).
  
• No reliable aftermarket replacements were identified by the users, so one suggestion was to use a 24‑volt electromagnet (DIY style) and fabricate a bracket to hold the pilot lever in position.
  
• Another user mentioned that on their L70F (a very similar loader), they simply use a rubber bungee cord to hold a valve in. While not elegant, it’s practical and easy to implement without messing with electronics.
  

Risks & Safety Considerations

• Using a magnet or solenoid to hold hydraulic levers engaged is powerful but potentially risky. If something goes wrong (like a hose failure or pump overpressure), having a dedicated e-stop is strongly recommended.
  
• Detents bypass the natural “dead-man” behavior of levers, so make sure anyone operating the loader understands how to stop the flow quickly.
  
• Modifying pilot control systems may affect warranty or system behavior; verify with a dealer or service manual.
  

Alternative Suggestions

• If the factory kit is truly unavailable, look into used Volvo parts suppliers or salvage yards; older L‑series loaders may have been retrofitted or parted out.
  
• Consider hydraulic flow control adjustments: sometimes, limited flow + proper joystick adjustment can mimic “constant-on” behavior without a detent.
  
• If building your own electromagnet setup, make sure to select a magnet with enough holding force and durability for constant use, and ensure the mounting bracket is solid.
  

Conclusion
Yes, it's possible to “lock on” the 3rd or 4th hydraulic function on a 2001 Volvo L70D, but it requires some work. The original factory option (detent kit with magnet) may be discontinued, so many are turning to DIY solutions (electromagnets) or simple mechanical tricks (bungees). The strongest advice from experienced mechanics: add a safety e-stop, so you can immediately disable the hydraulic detent if something goes wrong.