Case Study: Highlander power steering inoperative, noisy, unstable fluid level

Nov. 10, 2022

This Highlander was originally brought into the shop for unrelated maintenance work. After the work was done and with the engine running, the steering assist became inoperative, and the power steering pump was noisy.

Richard Diegle

Related To: ALLDATA

Vehicle: 2007 Toyota Highlander, 2WD, V6-3.3L (3MZ-FE), Automatic Transmission/Transaxle

Mileage: 162,558

Problem: This Highlander was originally brought into the shop for unrelated maintenance work. After the work was done and with the engine running, the steering assist became inoperative, the power steering pump was noisy, and power steering fluid was blowing out of the reservoir.

Case Details: After the fluid blew out of the reservoir, the fluid level inside the reservoir dropped low, and the steering assist returned. Shortly after that, the fluid level seemed to rise in the reservoir, and steering assist stopped working again.

NOTE: None of the hoses appeared kinked. Nothing in the power steering system was touched during the unrelated maintenance work.

An inspection of the reservoir revealed that the fluid was contaminated with gunk and sludge.

Confirmed Repair: On the advice of an ALLDATA Tech-Assist consultant, the technician removed the flow control valve from the pump and thoroughly cleaned it. He also disconnected the lines and blew them out, cleaned the reservoir and refilled/bled the system with fresh fluid. The technician road tested to vehicle. Problem solved!

Reprinted with permission from ALLDATA.

About the Author

Richard Diegle | Senior Automotive Editor for ALLDATA

Rich Diegle has been in the automotive industry since 1978. After graduating from a local community college, he began working at a Nissan dealership as a used car technician. Since then, he’s worked as a Nissan and ASE master automotive technician, shop owner, marketing copywriter, automotive editor, public relations manager, instructor, ALLDATA Tech-Assist team manager, and a senior automotive editor.