Aloha, I have a 01 Mazda B 3000 4WD. So I have this Whurring sound coming from underneath the truck. its there all the time, clutch in or out. the only time I dont hear it is when im going up a hill putting the motor under load. I would think if it was the slave cylinder it would change if you had the clutch pushed in? So Pilot bearing? Ive heard bearing that are bad, this isnt that kind of noise. its kind of a sequeling? Could it be a bearing in the trans? im kind of waiting for it to blow then I can fix something. So any ideas?

 

On the 3.0l any noise that could be described as squealing would point me at the Cam Synchronizer, top rear of the engine bay, known issue

Yes, pilot bearing or throwout bearing noise would change with clutch pedal position, so probably not those

And you don't mention if the noise is present when stopped and in neutral, engine running?
If it is then its coming from the engine, 100%

Did you check the ATF fluid level in the transmission?
On Drivers side of trans is the FILL hole, remove the plug and fluid should be at that level, get some on your finger and smell it, lol, just to see if a bearing inside trans is getting hot

 

yes, its there all the time, stopped and in neutral, engine running. I was wondering about the trans, in neutral, motor running so guessing the input shaft is turning?
I'll check today better on the cam sensor, when I turn the motor off you can hear it making the last turn of the motor.
thanks Ron

 

ok new info. it doesnt change with RPM. I took a stick and put it on the cam Synchronizer, all I could hear was ticking no squealing. driving to town in 5 gear 1500 RPM I can heat the noise , if accelerate putting a load on it. the noise will go away until it catches up to the RPM, like it was vacuum ? the only thing I know the other owner did was new rear main seal and clutch. if I pulled the cam synchronizer out and rotated it by hand could you feel it? what now? oh yeah, trans fluid was full and not burnt.

 

If it was the Cam synchro you would hear it easily

Something doesn't make sense
Noise is there when stopped
But doesn't change with engine RPMs, when stopped

There is really nothing I can think of that fits if these two statements are correct
Well one thing.................the RADIO, lol

 

im stummped? I even pulled the belt off thinking may be the idler or tensioner. nope? I doesnt change with rpm? when I turn it off I can hear it wind down. wurr, wurr. stop? oil pump? still makes no sense should change with rpm? its pretty loud too in the motor bay.

 

If you here a noise AFTER key off/engine off
Could be the EVAP system
Main EVAP system is behind the gas tank, but the Purge Valve is in the engine bay, Drivers side I think on the 3.0l
Its a vacuum system, so can certainly make noise, not related to RPMs or even with engine off, so I was WRONG, not just the radio, lol

Picture of the Purge Valve here: https://i.ebayimg.com/images/g/IpYAA...4MC/s-l300.jpg

 

I'll check Purge Valve today, question. if I pulled the vacuum hoses off at the manifold, One at a time. I think there's only 3 main ones could that pin point its vacuum it the noise stopped ?

 

not the Purge Valve, I pulled the vacuum line no change. So main bearing? or pilot bearing ? the pilot bearing has to be going all the time as long as the motor it running? Oil pump bushing? If it was the cam synchro I would thing it would change with RPM? But the noise doesnt change with RPM. I can hear it kind pulsation with the motor wa wa wa. the only time it goes away is when the motor is under a load? 5th gear 1200rpm and I give it gas, as it catches up to 2000 rpm the noise comes back. what would put a load on the motor to do that? Im still stumped, I can't fix anything if I dont know what it is.

 

You said noise didn't change with engine RPM, so not engine bearing

Pilot bearing supports the end of the input shaft, and it allows the input shaft and crank shaft to spin at different RPMs so you can shift gears
Pilot bearing is ONLY used when clutch pedal is down
When clutch pedal is up, while driving or in Neutral, the crank shaft and input shaft are both spinning at the same RPM, so pilot bearing is not "moving", inner and outer races are equal

 

Ok I really didnt think it could be the pilot bearing but I know its going around so, the sounds to me is kinda under the truck. its pretty loud down there. oil pump bushing? still could be cam synchro but I hear they chirp . or squeak , if I pulled it out could I tell?

 

You said the noise didn't change with engine RPMS????
Is that incorrect?

 

well not like I would think it would. it does some but not really to the true rpm

 

question, if I pulled out the cam synchro and spun it by hand could or would I feel or hear something ? at 3000 rpm it goes away or gets lost with the rest of the noise . I'll post video later today

 

No, probably not, its a bushing that wears out and makes the squealing noise and quite easy to hear, not at all ambiguous

 

here's a short vid

 

here's one more starting motor and turning off

 

I would be looking for a slight vacuum leak somewhere.

 

that was one of my first thoughts, I tried pulling all the major vacuum tubes off the manifold but nothing changed?

 

im thinking now its possible that its the Cam Synchronizer. the noise is not the same as the motor rpm, cam goes around at 1/2 as motor. in the last vid when the motor is turned off you can hear it wind down. I will check but thinking I'll try and listen real good at the Cam Synchronizer and hear it made that last noise.

 

That noise is not engine or transmission related.

Sounds more like a bad heater/ac fan

 

At 3000 rpm it goes away. And will change when there’s a load on the motor

 

Did you pull the vacuum line to the power brakes? There is also a vacuum reservoir for the climate control that can make some strange noises from the check valve inside. I don't remember where the source of the vacuum for that is. It could be the intake manifold and you may have already checked it.

 

yes I pulled all major vacuum lines put my thumb over them to check for a change. No change. ive ordered and new Cam Synchronizer After having someone in the truck starting and turning it off im pertty sure its the Cam Synchronizer. the noise it makes has a rhythm to it, but it not the same as the rpm of the motor, thats why im thinking Cam Synchronizer, half the rpm. if not I'll keep searching?