What Causes Power Steering Fluid to Boil?by Richard Rowe
The condition described by most as "boiling" sometimes isn't. Though excess heat in the power steering system can indeed cause the fluid to boil, there are other conditions that can mimic the effect.
The pressure side line of a power-steering pump can sometimes become pinched. This causes pressure to back up into the reservoir and gives the appearance of boiling.
A low-fluid condition may not allow the heat generated by the steering pump and rack to disperse, causing what's left to overheat and boil.
Power Steering Pump
A failing power steering pump will often generate excess heat through the grinding of worn bearings and gerotors. The fluid on the low-pressure side of the pump will begin to boil and rise through the reservoir.
Rapid back-and-forth sawing on the steering wheel can cause an overheat condition in the rack-and-pinion steering.
After it has been overheated, power steering fluid loses much of its lubricity and resistance to future super-heating.
- Image by Flickr.com, courtesy of Reg Mckenna