Hi guys, I have a 1990 4x4 Pickup V6 with a manual transmission and manual locking hubs (no ADD). I've started getting some intermittent vibration along with a buzzing noise coming from the front diver side of the truck at highway speeds. It sounds almost exactly like driving over a rumble strip or drainage channels cut in the pavement. When I unlock the hub the sound goes away. Should I be looking at the tire, the hub, the wheel bearing or all of the above? The truck's basically parked until I can sort this out. Things I checked: the lug nuts are tight and correctly torqued. The CV boot is intact and not leaking. I don't see any obvious damage or wear to the steering linkage and suspension. The grommets appear to be intact. No obvious looseness in the components. The tire is in good condition. The hub appears to function normally. It's not hard to lock, and it does actually lock he wheel. Any suggestions about what to look at would be appreciated.

 

if unlocking changes the sound/makes it go away, then you need to look at the parts that move only when the hub is locked. the tires/wheels clearly still rotate when unlocked, and the wheel bearings are functioning at that time, too.

 

I agree that the locking hub is likely involved. Any ideas what U would be looking for, or do I just toss it and install a new hub ($100 at yotashop). While I’ve done a good amount of work on the engine, I’ve never torn into the hubs before.

 

hubs, if aisin, are pretty robust. the hub isn't necessarily the problem. even if it is the hub, i'd rebuild it (if it is an aisin). cv axles spin when the hubs are engaged. so does the front diff and driveshaft. lots of things to rule out before throwing parts at it.

 

Listen to Wally, could be hubs aren't assembled correctly, OR spindle bushings, OR CV axle, OR, front diff, OR noise transferring from somewhere else like front driveshaft.
jack up the front end and start fiddling with the cv axle to see if it has issues, lock and unlock the hub to see if it locks and unlocks, check for play where the CV axle goes into the spindle.

 

I replaced the rear pinion seal about a month ago. If the propeller shaft was rotated 90 degrees when I reattached it, could that cause a buzzing vibration? Or would any noise made by the propeller shaft be constant instead of only happening when the front wheels are locked?

 

since it was the rear pinion it is almost 100% that it would be vibrating and/or making noise all the time, not just in 4x4
another thing you could try for diagnostic purposes is to lock the hubs while in 2wd and see if it also makes noise or lock only one hub at a time while in 4x4
it isn't likely that anyone can tell you 100% what your problem is, you will still need to wiggle/test/disassemble and have a look yourself or you risk throwing a lot of parts and money at it.

 

That is a point I didn't include. The buzzing is happening when the wheel hubs are locked, but the truck is in 2wd. I haven't heard the noise in 4wd, but that could be because I don't usually travel at highway speeds while off road. The Toyota Service Manual has a list of things to check, but they all seem to belong to the "take it apart to check" variety, like worn or chipped gears or check axle shaft bearing for wear. I guess the way forward is to walk through the troubleshooting sections on suspension / axle and propeller shaft.

 

I have seen a similar issue several times in the past, I'm convinced that one of your hubs isn't assembled quite right keeping it from completely disengaging the cv shaft from the wheel hub. it's just barely unlocked but still skipping across the end of the splines.
I would bet that if you swap the locking hubs from side to side your noise will change sides. putting them together correctly is a little tricky and not easy to explain.

 

Thanks for the advice, I will keep it in my mind.