Finding bearing noise.

I'm trying to locate a noise myself prior to taking my new (to me) Taco to a shop (although I got a recommendation from the PNW forum that I'll use if I can't figure it out myself).

Edit: Truck info: '04 Ext Cab, 150k miles, 5-spd V6

What I know:
Noise when driving over about 25 mph, the frequency isn't too fast (happens like once a second @ 30mph) - but it's following and speeding up with speed.
- Isn't affected by 4wd
- Isn't affected by turning
- Isn't affected by load on drivetraing (e.g. seems to be the same regardless if Ii'm accelerating vs. coasting)

- Breaking MIGHT affect it... Hard to tell, completely, but if I push the breaks hard I can feel a pulse in the pedal that is in sync with the noise until it drops below 20-25mph.

- Just had new tires put on it, and the noise didn't change from old tires to new tires.

CV boots, at quick glance look Ok. Any thoughts? I'm happy to do some more tests!

Thanks.

 

try shifting/putting trans in neutral and see if it is still there.

 

If the noise (you didn't say what the noise sounds like - a click, a squeal, whatever) repeats once per second at 30 mph then it's not a drive-train noise. That's because everything is moving, turning, faster than once per second. I have not the foggiest idea what the noise is, but to me it sounds as though it's something in the electronics/electrical system. Maybe a relay turning on and off, maybe a vacuum valve or switch opening and closing, something like that.

Like Glamisman said, put the truck in neutral and rev the engine up to 2,000 rpm. Listen if the noise is still there.

Can you record and post the noise? What does it sound like at 60 mph? Whatever it is, better fix it though. Please keep us posted.

 

Good call - forgot a fairly important detail. It sounds mechanical, like what I think a dying bearing would sound like, almost grinding-like, but not that intense. I'll test those two things and see if I can record the noise. At 60 mph it's hard to hear over road and engine noise, but I think it's still there.

 

I had some similar noise like that in the past. It was a nasty grinding sound that would growl at me. It would up being the left front spindel bearing that I took to a shop and got a new one pressed in.
I have 220,000 miles on my 2001. It fixed the problem and made it so people weren't staring at me when I was driving by.

 

One thing that is confusing is the once per second cycle. That is very slow in a vehicle moving 30 mph.

The engine turns thousands of times per second in that scenario. Even the differentials or wheels would be waaaay more often than that. For example, a wheel rotating at 30 mph would have about 300 revolutions a minute which equates to 5 times a second. Pulsing in the brake pedal would be similar.

 

I agree - at 30mph all driving components are moving much faster than 1 per second. I wonder if I'm catching something early so it's only making a loud enough noise every couple of turns?

 

what I have heard of people doing is to take an cell phone that can record sound and affix it in various places under the car and go for a drive then replay and listen then move it or

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Update - shifting into neutral / coasting / clutch etc. while moving does not affect the noise.

Also - I drive barefoot yesterday to test out the brake pedal - and I'm definitely feeling more than one "bump" while breaking hard, and then a big "bump" telegraphing with the audible noise. So although I can hear it once per section while driving, what ever is making the noise, if it is what's telegraphing into the brake pedal is happening more frequently.

So new question - what grinding noise could telegraph through the brake pedal?

 

pulsating in the pedal usually means pads or rotors are going bad. maybe the rotors are galled/overheated. Front bearing isnt out of the question. Try jacking one tire up off the ground at a time or front end off the ground and see if you can get the noise to surface then. If not I'd also look at your u-joints and center bearing.

 

Could be your ABS pulsating, which is what it does on hard braking.

 

Good call - but I'm not breaking that hard, and I'm not seeing the ABS light come on.

 

ABS light will only come on if theres a fault or problem with that system...IIRC

 

Gotcha - it doesn't feel like the ABS pulse - it's uneven in frequency and strength... unless there is something wrong with the rotors as previously suggested and that's messing with the ABS application? I'll jack it up this weekend and take a look, spin the wheels and see if I can feel any grind.

 

Wheel bearing. Drive at 50mph or more on a curvy road windows up, stereo off. Wheel bearing noise changes when cornering.

 

That's right. I had that noise back in 1993 on my Toyota truck. It was a front wheel bearing.