2005 Tacoma Mystery

[MrH]

Ok, as I've talked about in my car shuffle thread in the General Automotive section, I'm the proud owner of a 2005 Toyota Tacoma right now.  4-cylinder, 5-speed, extended cab, 4x4 with the SR5 package.

Anyways, I have a pretty loud, speed dependent humming noise coming from the front driver side area.  It doesn't change with engine speed, but with vehicle speed.  Doesn't matter if I'm in neutral or which gear.  The noise goes away completely if the wheel is turned about 15-20 degrees left.  It also causes a very non-linear steering feel.  As in, I hit basically these big lumps while turning the wheel, where it feels like I have no power steering.  Makes driving it pretty interesting sometimes when you hit 10 degrees of turn with essentially no power steering.  I immediately thought wheel bearing because of the speed dependent hum.  Took it to the garage at school and looked at it with Crosswire (he used to post here a long time back).  Jacked it up, pulled on the wheel, and there's really no play like there should be with a bad wheel bearing.

I was kind of confused.  Got under the truck and started checking things out.  Left CV joint had a ton of play in it.  I thought, "Great, that's what it is.  That explains how it could be effected by the steering input too."  A full afternoon of frustration with Crosswire and about $80 in parts, and the half axle was replaced.

Didn't solve the problem though.  

I'm hearing it could still be a wheel bearing issue, despite passing the push and pull on the wheel for excessive play test.  Doesn't really explain the steering issues though, which seem to have gotten worse in the last week, especially when the engine is still cold.  It just hit me tonight when I was thinking about it, it might be a combination of low power steering fluid and a bad wheel bearing.  I'll be checking the power steering levels in the morning when it's light out.

What do you guys think?  Any suggestions would be helpful.

[Secret Chimp]

A bad wheel bearing isn't going to cause "lumps" in steering effort or make it feel like you've completely lost assist. If the pump is low on fluid, it shouldn't completely go away the more you crank it, and the pump noise would be dependent on engine speed, not vehicle speed. I would wonder what happens to the noise if you engage the 4WD. It sounds like the differential/front hubs might be engaging and binding up when it/they shouldn't. That's my pull-it-out-of-my-ass guess.

[MrH]

A bad wheel bearing isn't going to cause "lumps" in steering effort or make it feel like you've completely lost assist. If the pump is low on fluid, it shouldn't completely go away the more you crank it, and the pump noise would be dependent on engine speed, not vehicle speed. I would wonder what happens to the noise if you engage the 4WD. It sounds like the differential/front hubs might be engaging and binding up when it/they shouldn't. That's my pull-it-out-of-my-ass guess.

Putting it in 4WD doesn't change anything.  I thought it could have been that too, so I tried it both in 4 HI and LO with nothing different.

If it's not a combo of a wheel bearing and power steering problem, it can only mean one thing.  I'm fucked.  It's probably front differential bearings. 

[Secret Chimp]

Oh, what a feeling!

[Laconian]

(jumps and pauses in mid-air)

[GoCougs]

My recommendation is to take it to a shop to get a diagnosis; that they may charge you $95 or whatever will be cheap in hindsight. Replacing parts without troubleshooting is a frustrating/expensive/time-consuming way to go about these things.

The chances it's front diff bearings causing this problem are astronomically small. Any bearing anywhere in the drive train bad enough to FUBAR steering would eat itself almost immediately making the solution obvious.

If I had to guess to save the world to me it at a minimum it sounds like a classic example of a bad steering rack; turning issues are obvious; problem worse when cold = when PS fluid is cold (thicker); speed dependent grumble may be unrelated.

[280Z Turbo]

What does the tire look like? What is your toe set at?

[mzziaz]

....to save the world to me it at a minimum it sounds like a classic example of a bad steering rack; turning issues are obvious; problem worse when cold = when PS fluid is cold (thicker); speed dependent grumble may be unrelated.

Thats my guess too.

[MrH]

My recommendation is to take it to a shop to get a diagnosis; that they may charge you $95 or whatever will be cheap in hindsight. Replacing parts without troubleshooting is a frustrating/expensive/time-consuming way to go about these things.

The chances it's front diff bearings causing this problem are astronomically small. Any bearing anywhere in the drive train bad enough to FUBAR steering would eat itself almost immediately making the solution obvious.

If I had to guess to save the world to me it at a minimum it sounds like a classic example of a bad steering rack; turning issues are obvious; problem worse when cold = when PS fluid is cold (thicker); speed dependent grumble may be unrelated.

I'm a broke college student with time on my side.  Shops seem to think this might take awhile to diagnose too.  So I'll play Mechanic Mr. H for awhile longer before I throw in the towel.

What does the tire look like? What is your toe set at?

 I just got the truck.  No idea what the toe is set at.  Doesn't look abnormal at all.

UPDATE: So I thought there was potentially not enough power steering fluid.  I tried to check real quick before driving to class, opened the hood, touched the cap, and noticed it was just filthy, so I decided to look at it later.  The steering got progressively worse.  I finally checked it, and it wasn't screwed down properly.  I checked the levels, and they were fine, and screwed it back on right.

There was a crazy downpour.  Flash floods everywhere, over a foot of standing water in most parts in the street.  I threw it into 4WD just to be sure, and the steering magically fixed itself.  Not sure if it was binding like Chimp suggested or there was air in the system.  I'm leaning towards the former.  I've been cycling 4HI on and off to loosen it up if it was indeed binding.  Before, I tried 4HI briefly and it didn't fix the problem, but running it in 4HI for awhile seems to have done the trick.

This is the first encouraging news in awhile with this truck.  Still have the hum, but that seems like a simple fix.

[GoCougs]

FWIW, cycling in/out of 4WD "fixes" the problem = unfortunately something somewhere is still FUBAR.

[MrH]

FWIW, cycling in/out of 4WD "fixes" the problem = unfortunately something somewhere is still FUBAR.

Why do you say that?  It probably hadn't been in 4WD for who knows how long.  Something was probably binding up.  I haven't had any problems with the steering since.    Could have been the power steering cap too.  Who knows, who cares?  Works great now. 

[GoCougs]

Why do you say that?  It probably hadn't been in 4WD for who knows how long.  Something was probably binding up.  I haven't had any problems with the steering since.    Could have been the power steering cap too.  Who knows, who cares?  Works great now.  

Simply because there's nothing that can bind when everything is working properly. A part time Tacoma t-case is just a set of gears - there are no clutches or viscous couplings. From there it's a drive shaft + couple of u-joints out to the open diff (i.e., no locker or clutch packs) and then from the diff out to axles + cv joints and then the locking hubs.

Chances are one or more of the "links" is shot - u-joint, cv-joint or locking hub - or perhaps everything is only slightly bad leading to a cumulative binding effect. The reality is most any 4WD rig with any sort of miles will be in the same boat. The issue is by the time a rig gets to this point it isn't always feasible to fix everything. Taking it to a shop would cost an arm and a leg and doing it one's self would be difficult and time consuming.

I've had a couple of such rigs that were driven 50k+ miles with one or more drive line components bad yet the 4WD still worked, albeit with clunks, shudders, and stuff like you have noted in this thread. More often than not people just live with it.