Whirring/motor noise behind panel.

[Zorrota]

2001 4WD. I searched and wasn't able to find an answer.
When I start the engine, there's a whirring, motor/pump like noise from behind the panel or under the hood. It continues for 10 seconds or so and recurs periodically as I'm driving it. There's a very definite hard click when it starts and stops, no gradual ramp up or down.
I haven't opened the hood while it's running to check for it but it's very obvious from the cab.
It's not the power antenna. That SOB is disconnected and stays in one spot.
I saw ABS system mentioned somewhere as a possible source for the noise.
Thoughts?
Thanks to all!

 

[BrianSD_42]

Any chance your climate control / fan is on and blowing air?

If you turn it to off setting (no air movement into cabin) does the sound go away?

I ask because I just started having a similar sounding issue that only occurs when AC/fan is on.
.

 

[alumarine]

Could it be your A/C compressor?
It will run when defrost is selected.

 

[thezentree]

It's that weird electronic brake booster thing Toyota put in later 3rd gens. Mine does it too.

 

[96RedRunner]

It's the ABS hydraulic pump building pressure in accumulator. Right conditions you can hear it while driving.

 

[Rancho5]

My 02 does the same thing when it starts up. By the time I back out of the garage it stops.

 

[96RedRunner]

It is normal to run after sitting for extended time.
If the pump never stops you have a problem.
Under certain driving conditons heavy stop n go it runs on my 01 for 5 secs or so
occasionally.

 

[gamefreakgc]

Yup, ABS pump on newer years. My '02 would do it.

Just monitor it. Noise is ok, but if it gets louder be kind to it and make sure the fluid is fresh. The unit is very expensive to replace.

 

[96RedRunner]

Two reasons not to buy 01, 02 ABS master cylinder and transmission.
Had more faith in 96red with 375k on it than 200k 01.

 

[Zorrota]

Sounds like it's the ABS pump then. Not the climate control since it does it regardless of the setting.
I probably should change out the fluid to try to avert a pump replacement.
Thanks all!

 

[96RedRunner]

I probably should change out the fluid to try to avert a pump replacement.
Thanks all!

Would be nice to be able to change just pump, unit only from dealer if you want new.
Turn key to Ign position for bleeding brakes.

 

[Ifirefight]

Two reasons not to buy 01, 02 ABS master cylinder and transmission.

Had more faith in 96red with 375k on it than 200k 01.

Educate me on the transmission. FYI, my sons 01 makes the same noise..I was wondering what that was. Thanks!


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[96RedRunner]

Educate me on the transmission. FYI, my sons 01 makes the same noise..I was wondering what that was. Thanks!..

Part of what I said comes from having 01 only 12k mi of 211k and failures I've read and researched on both.
The ABS/MC is a split mini hydraulic system with spools, O-rings, pump, accumalator.
The M/C part see's usage whenever brakes are applied, so spools don't get stuck to O-rings.
The ABS side, has spools and O-rings that very seldom if ever get movement. Stick together from age and lack of movement,
when movement happens tears O-rings.
With this in mind I function ABS side whenever streets are wet. So far so good.

01 is first MY of this version A340F DBW kick down, TPS controlling trans more.
Along came failures of the Overdrive planetary gear part of trans when they fail.
I can tell a difference in the operation of the two, with the win going to 96 with 170k more miles.
The Trac system sucks also, Andy mod covers that.

 

[gamefreakgc]

Sounds like it's the ABS pump then. Not the climate control since it does it regardless of the setting.
I probably should change out the fluid to try to avert a pump replacement.
Thanks all!

A new ABS pump is more expensive than a replacement engine, for reference.

 

[96RedRunner]

Sale price $2,117.74 2k more than pre 01.

 

[Zorrota]

Sale price $2,117.74 2k more than pre 01.

Bad word!
What's a poor boy to do? If this fails can you run it long-term and just know you don't have ABS or does it disable or reduce your braking function? What preventive maintenance steps can be taken?
Thanks 96RR.

 

[wlfmachine]

There are videos on YouTube of someone replacing just the electric motor that runs the compressor for the ABS master cylinder. From his video you can find the exact part number of the electric motor and its a little more then $400, and the job of swapping out the motor doesn't look too bad.

Twice now I have had that motor run backwards for a few seconds, causing a horrible screeching sound. When I stopped the truck the motor stopped turning the wrong direction and it hasn't happened for a while, but I know that is a sign of the motor getting ready to go out. That's when I started looking up how to replace it.

Definitely better to replace just the motor then the whole ABS Master Cylinder.

[edit]Looked it up... here is a link to the part that would need to be replaced:
2001 - 2002 Toyota 4runner *NEW* Abs Pump and Master Cylinder Repair Electric Motor - Wholesale Parts Express

 

[96RedRunner]

[MENTION=230481]Zorrota[/MENTION], Start saving, Lol. Believe me I'm working on a plan.
There is one person on forum that has done a swap to pre 01.
Used is a option +- $600 range if lucky.
What happens when it fails depends on what part fails.
My info gets spotty on what happens when certain parts fail.
If brake pedal plunger seals of MC = no brakes, rebuild kit is $70.
The spotty part, Motor or Accumalator have brakes like in old days before power brakes no ABS. Maybe limp mode.
Motor/pump last I checked was $1100, Accumalator $350.

I've done all I can by flushing system a bunch with good Syn fluid when I first bought it.
When it rains I lock em up to function ABS.
Not trying to freak people out mentioning this, part of having a 01 02 there are cases of failures not a lot but it's there.

 

[96RedRunner]

2001 - 2002 Toyota 4runner *NEW* Abs Pump and Master Cylinder Repair Electric Motor - Wholesale Parts Express[/url]

That's option hadn't seen. I have to wonder though if it's really the motor that's a problem. Parts diagrams don't show a check valve could be built into pump or accumalator bad/faulty check valve would cause motor to turn backwards.
Has to be a check valve in system for it to work.

 

[Road Bull]

My turn!

So I am getting that horrible screeching sounds after start up. I hear it after morning and after work start ups when the vehicle has been sitting for hours.

YouTube

Anyone have any good news fixes they want to share?