What could be the source of this noise?

[txslg]

2004 LC with 175K miles. bought it 6 years ago and perform maintenance by myself. It has been rock solid for the past 6 years. But recently, it start to have strange noise behind the dashboard. I am in Houston area, so weather start getting cold recently. I am still not sure about the pattern of the noise. But typically it happens during morning cold start. I thought it was related to power steering, but the noise come even without moving the steering wheel. There is no lights on the dashboard. Everything works just fine.

What could be the source of this noise?




I searched many post about noise. None of them sounds like mine.

 

[01138lex]

Sounds like a bad servo motor for your hvac system... is your hvac set to auto??

Servos are a big job... requires dash removal

 

[nukegoat]

Is it only when the engine is running? Does the vehicle have to be moving or in drive?

I'm leaning more towards something in the VGRS, but I don't really have a good reason why

 

[2001LC]

Sounds like your brake booster accumulator. Next cold morning before putting in the key. Open the hood and video the brake reservoir from front as you turn IG switch to on (no need to start). Then, Turn IG switch off and pump brake pedal 40 times. Then turn IG on again and time how long booster motor runs as you video the brake reservoir. Keep camera shooting the reservoir at all times. Also count how many times you pump the brake pedal, until foot pressure is lost (pedal goes to floor).

Next you be getting alarm and ABS, VSC lights. It could be day or months but it coming.

 

[txslg]

Sounds like a bad servo motor for your hvac system... is your hvac set to auto??

Servos are a big job... requires dash removal

Yes, when I record the video, the AC is running.

Sounds like your brake booster accumulator. Next cold morning before putting in the key. Open the hood and video the brake reservoir from front as you turn IG switch to on (no need to start). Then, Turn IG switch off and pump brake pedal 40 times. Then turn IG on again and time how long booster motor runs as you video the brake reservoir. Keep camera shooting the reservoir at all times. Also count how many times you pump the brake pedal, until foot pressure is lost (pedal goes to floor).

Next you be getting alarm and ABS, VSC lights. It could be day or months but it coming.

Thanks for these detailed steps. I will check it during the weekend.


So this morning, I started the car without turn on the AC and drove to work. The noise did not come. So on surface, it seems like HAVC related.


Thanks you again for all your help.

 

[MongooseGA]

I agree with @2001LC . It sounds like the brake pump motor to me. Does it seem to be coming from the driver's side of the dash mainly?

 

[txslg]

I agree with @2001LC . It sounds like the brake pump motor to me. Does it seem to be coming from the driver's side of the dash mainly?

Yes, mainly from the driver side of the dash.

Just checked the part price, it is a $1000 part. Ouch!

 

[MongooseGA]

It can be had much cheaper. Check the thread about brake failure at the top of the forum. It's a well-known and well-discussed issue.

 

[Keowee]

Sounds like your brake booster accumulator.

I agree. That noise began on cold mornings with mine. The brakes failed later on. Lucky that I was off road.

 

[txslg]

I agree. That noise began on cold mornings with mine. The brakes failed later on. Lucky that I was off road.

Wow, if it is brake related, then I have to get it fixed ASAP.

 

[Keowee]

Wow, if it is brake related, then I have to get it fixed ASAP.

Yeah. The noise is identical to how mine sounded. About a month later I was seven miles into the woods and on the brakes more than normal.

It started screaming like a banshee and the pedal dropped almost to the bottom. Drove out in a low range crawl while my wife was screaming too.

I did the brake pedal pump as @2001LC described and the pedal came back good so I drove home slowly. Then spent lots of money.

 

[txslg]

Yeah. The noise is identical to how mine sounded. About a month later I was seven miles into the woods and on the brakes more than normal.

It started screaming like a banshee and the pedal dropped almost to the bottom. Drove out in a low range crawl while my wife was screaming too.

I did the brake pedal pump as @2001LC described and the pedal came back good so I drove home slowly. Then spent lots of money.

Did you do it by yourself? Can you let me know your cost? I am just afraid to bring the car to dealer.

 

[Keowee]

@txslg No dealer work. Too expensive for me. I did the complete master cylinder assembly but you can do the motor and pump only for less money. Lots of knowledge about that here on Mud.

It's been a few years and I spent about $2000.00. Part prices are probably more now.

 

[2001LC]

Although this could be bearing of HVAC blower motor. You need to focus on brakes first. It's for your safety.

We've seen number of these accumulators (not motor or pump) failures lately, as temperatures (OAT) have been dropping.

I find in early stage they vary on when you'll hear the screeching. Most often heard when system and OAT cold. As the brake systems is activated/used, it warms up, then start working normal. While cold the booster run time test can vary greatly. Times form booster motor not shutting off (More than 2 minutes booster motor run time is damaging to motor), 55 seconds, 45 second and then within spec at 38 seconds. Those times are just one example.

Before I go off on a super long post and cost, etc. Which this may be as cheap as ~$200 to fix. Let's see if it is a brake issue. Test the times ever morning first thing, is your best course of action. Waiting until weekend is risky. At minimum keep all sound in cabin off i.e. open windows, radio, HVAC, etc. so you can hear the booster motor. If motor does not stop within second, while using brakes. Actively use brakes to warm up accumulator, and then let rest by shutting down (IG key off) for a few minutes. If motor still does not shut off when key turned back on, shut down (don't drive), or you'll burn up a very pricey motor.

Here one screeching that I barley caught on film. Watch very close as you hear the screeching at ~1:10 minutes into video. You'll see bubble come up in reservoir. Time to full pressure on this was was only slightly over spec, at 43 seconds. Then after short pause motor started up again. This indicates pressure drop WHY! Then we hear screech and see bubble in reservoir. In this one it took 38 pumps of pedal until feed back pressure dropped off (reaction force became light).
Also notice how reservoir is over filled. FSM is very clear, do not over fill. Overfilling does not cause accumulator failure, but has some very bad affects.

 

[txslg]

Although this could be bearing of HVAC blower motor. You need to focus on brakes first. It's for your safety.

We've seen number of these accumulators (not motor or pump) failures lately, as temperatures (OAT) have been dropping.

I find in early stage they vary on when you'll hear the screeching. Most often heard when system and OAT cold. As the brake systems is activated/used, it warms up, then start working normal. While cold the booster run time test can vary greatly. Times form booster motor not shutting off (More than 2 minutes booster motor run time is damaging to motor), 55 seconds, 45 second and then within spec at 38 seconds. Those times are just one example.

Before I go off on a super long post and cost, etc. Which this may be as cheap as ~$200 to fix. Let's see if it is a brake issue. Test the times ever morning first thing, is your best course of action. Waiting until weekend is risky. At minimum keep all sound in cabin off i.e. open windows, radio, HVAC, etc. so you can hear the booster motor. If motor does not stop within second, while using brakes. Actively use brakes to warm up accumulator, and then let rest by shutting down (IG key off) for a few minutes. If motor still does not shut off when key turned back on, shut down (don't drive), or you'll burn up a very pricey motor.

Here one screeching that I barley caught on film. Watch very close as you hear the screeching at ~1:10 minutes into video. You'll see bubble come up in reservoir. Time to full pressure on this was was only slightly over spec, at 43 seconds. Then after short pause motor started up again. This indicates pressure drop WHY! Then we hear screech and see bubble in reservoir. In this one it took 38 pumps of pedal until feed back pressure dropped off (reaction force became light).
Also notice how reservoir is over filled. FSM is very clear, do not over fill. Overfilling does not cause accumulator failure, but has some very bad affects.

View attachment 2148751
View attachment 2148752

Can't wait to see your write up about this issue!

This reminds me the noise made by my pool pump. When temperature drops around freezing, my pool pump start making very similar screeching noise. Searched online, someone says the pool pump bearing is on the way out.

Could it be similar cause? when temperature drops, some of the bearings are worn out so it starts making these noise?

 

[2001LC]

If what I think it "may" be, it's not booster pump or motor. It is booster accumulator issue.

The booster accumulator is just the large gold cylinder on side of master.

Brake Booster pump Assembly is: Accumulator, Pump attaches it and Motor attaches to pump.

 

[2001LC]

We are really getting ahead of our-self. First lets get pinpoint the best we can.

 

[CloudCity]

That's definitely the start of the Dying Seagull (brake system failure) and I would put money on it not being the HVAC servo. Those sound buzzier and not that loud.

 

[txslg]

Last weekend, I spend some time to change all the fluid of the truck.
Bleed the brake line
Changed the power steering fluid with Toyota ATF fluid
Changed Transfer case front/back differential with Mobile 1 Synthetic 75-90W Gear oil
Lubricated the driver shaft

After all these changes, I haven't heard the noise yet. It is pretty cold now (40F is consider cold in Houston.). So the noise should come but hasn't.

I am not sure if the problem is totally addressed. I think the change of brake fluid might help on the pump. The brake fluid might be burned out. It has some brownish color.

Thanks everybody for your help! It helped me tremendously. Believe it or not, I lost few nights of sleep just think about bring the truck to dealer

 

[txslg]

Some more update on this in case some body is interested.

I just returned from a 2000 mile trip to New Mexico for Skiing in the mountains. As you can imagine, it is very cold in the morning near the ski resort. I remember seeing 22 degree. So it is very cold.

I am glad to report that, for the whole trip, I didn't hear that noise at all. It seems like bleeding out the old brake fluid helped the issue if not resolved.

Happy new year!