Toyota 4runner Locking Hub
Common Toyota 4Runner Locking Hub Issues and Their Causes
The 4Runner's locking hubs allow the front wheels of the vehicle to disengage from the drive shaft. Though the hubs are made as tough as the vehicles they are installed in, wear and tear will eventually take hold of them. As a result, the locking hubs won't function as intended, which is something to fret about. Read on learn about some of the common problems of Toyota 4Runner locking hubs and their causes.
Extreme difficulty in locking or unlocking the hub
If you have trouble locking or unlocking the hub, it means that the mechanism of the locking hub has likely worn out. Try removing all the components of the hub and then clean and lubricate them before reinstalling them on the 4Runner's wheel. If that won't do the trick, you may have to rebuild or replace the unit.
Clicking sound when the hub is locked and four-wheel drive is engaged
A clicking or grinding sound means that a number of the hub's components, such as the bearings, might be failing. You can rebuild the locking hub and replace the necessary components if possible. If not, just have the whole thing replaced.
Locking hubs won't engage when 4Runner is in four-wheel drive
When your locking hubs won't engage while in four-wheel drive, it means that there's a problem with the transfer case. If the 4x4 shift motor or the bushings are worn out, fixing them might solve your problem. The locking hubs themselves may be malfunctioning. Replace the necessary components of the hub or buy a new replacement unit instead.
Hubs won't unlock
Locking hubs are usually operated by a vacuum system. A vacuum leak at any point in this system or a malfunctioning vacuum solenoid will make it virtually impossible to engage or disengage the hubs. Fixing the vacuum leaks will usually solve the problem.
Front wheels are not moving in four-wheel, low-speed drive mode
This is a common issue with the 4Runner's automatic locking hubs. There's not much that can be done in this case except to replace your auto locking hubs with manual ones.
Manually spinning the locking hubs by hand is one of the best ways to test their functionality. This can be done by suspending the front part of the 4Runner with jack stands. With this, you can turn the wheels while observing its effects on the 4Runner's drive shaft.