Brake master screeching when cold - trip planned tomorrow (1 Viewer)

[2001LC]

I had the same issue. The reservoir would fill and then screech and bubble.
I consider the pump = pump and motor unit. You cannot purchase the pump or motor on its own, they are a unit. You can purchase the whole unit, the pump/motor and the master cylinder.

I see! So you had the issue of screeching noise before and after a new OEM booster motor/pump w/brake control wire assembly installed and rebuilding the old brake master, by replacing the master cylinder plunger. You replaced & rebuilt to correct screeching noise!

So to come up with this conclusion the HP SW stuck/sticking, did you run through the test procedures given in the FSM?

 

[Tanner H]

@dbfw I'm currently working on the same issue (seagull for a few seconds only in the morning and then goes away, no warming lights or alarms). Heres what I've done so far that might help you.

-i pulled off the accumulator with an oil filter wrench to inspect the ring/pin/spring (Found some fj cruiser guy that solved his issue for free this way). Zero change and all this stuff appeared to be fine (I placed an order for all three new parts but i have a feeling it wont do anything)

accumulator three amigos if you choose to throw a few bucks at your problem:
o ring: 9030113014
silencer tube: 4795530010
spring: 9050116160


-bled brakes. dirty fluid came out and i went through two tall bottles of fluid. then went for a test drive...felt great/zero issue. I woke up the next morning and no seagull (awesome). However, the morning after that...seagull came back but very very quiet now. So I might bleed again to see if it removes it completely.




-My next step (and i think is the problem solver) is to bite the bullet and buy a brand new abs motor from Wholesale parts express for about $500. As a few people have solved their noise issue with this. Others with noise plus alarm and light on have had to go full assembly.

link to motor: 1998 - 2002 Land Cruiser / LX470 New Abs Pump Master Cylinder Repair Electric Motor - Wholesale Parts Express - https://www.wholesalepartsexpress.com/product/new-4runner-land-cruiser-abs-pump-master-cylinder-repair-electric-motor-2000-2002/

 

[grundsethp]

I ran thru the service manual procedure. See the attachments for the system diagrams.

 

[grundsethp]

Previous thread that should help:

Booster Pump / Accumulator Noise diagnosis

Used? Not remanned? How many miles were on the donor? It didn’t say. It said that it was tested and they offered returns. I’m going to work on it tomorrow. Maybe open up the black box and see if I can see anything obvious. I don’t even really know what I’m looking for. I’m leaning towards...

forum.ih8mud.com

 

[2001LC]

I ran thru the service manual procedure. See the attachments for the system diagrams.

View attachment 2586414

View attachment 2586416

Can you share readings/results you got, pointing to the HP SW?

 

[dbfw]

As an academic exercise, I'm curious to see the results of these repair attempts and will be following along closely.

In my case, my mind would never be at ease after experiencing this, knowing there are other failure points at this age and mileage. It took me a day or two to come to terms with the hit to the savings account, but am currently having the entire MC / booster unit replaced. This truck is my daily driver, and planned to be a long term keeper, so it will actually be a great relief to know this is all new.

 

[dbfw]

Closing the loop on this, I'm just back from the shop with the new unit (47050-60010) installed. Confidence restored and another big repair checked off on this truck. Some interesting A/B observations:

1. The brakes feel great, less spongy pedal than before, likely due to old worn piston seals, etc.

2. QUIET! I had no idea how loud the old booster pump/motor had gotten. It is now barely audible from inside the car with radio and HVAC off. Before it was clearly audible if radio was at a low volume and HVAC fan on low

Here's to another 200,000 miles + of worry-free braking...

 

[CloudCity]

Hmmm, I also have a dying seagull in my engine bay but I didn't think it was coming from the brake system. Fades away after a few seconds and happens when it is very cold out.

14 Seconds
>>

This is all just my gut talking so by no means eliminate the brake assembly as a possible cause, but that sounds like a power steering pump squeal to me. Since you say it happens when it's cold I wonder of the fluid is thick enough at first to not be able to pass a clogged filter but once it warms slightly it's thin enough to start moving through? The PS reservoir has a moulded screen so you can't easily clean it, the old fluid goo really sticks, and those of us who have tried usually just end up buying a replacement reservoir.
The simple way to find out is to have somebody else start it for you while you listen at each of those two spots. Use a mechanic's stethoscope if possible as sounds can travel in these, and especially PS related ones.

 

[Boss Hog]

So just yesterday I got new rotors, pads, and calipers (all on the rear only) and a brake flush. This am I get the dying seagull. Any chance they are related?

 

[flintknapper]

So just yesterday I got new rotors, pads, and calipers (all on the rear only) and a brake flush. This am I get the dying seagull. Any chance they are related?

Nope.

All work done is 'downstream' of your sound/issue.

You have a pending pump/accumulator problem.

 

[Boss Hog]

Nope.

All work done is 'downstream' of your sound/issue.

You have a pending pump/accumulator problem.

I was only hoping…

 

[2001LC]

So just yesterday I got new rotors, pads, and calipers (all on the rear only) and a brake flush. This am I get the dying seagull. Any chance they are related?

Watch for bubbles coming up front of reservoir at same time you hear "dying seagull". If seen; Non replaceable seal in master.

Caliper replacement "may" be related. In that caliper piston seals are now sealing better. Thus entry system holding more pressure. This increase in pressure, to near factory level, revealing weak seal in master.

 

[Boss Hog]

Watch for bubbles coming up front of reservoir at same time you hear "dying seagull". If seen; Non replaceable seal in master.

Caliper replacement "may" be related. In that caliper piston seals are now sealing better. Thus entry system holding more pressure. This increase in pressure, to near factory level, revealing weak seal in master.

Makes a lot of sense. How hard is it to replace the master? What if no bubbles are seen?

 

[2001LC]

It's not hard to replace, for me. But I've pulled many.

You can buy just master, w/out booster assembly. But best to just buy complet master w/booster assembly. Saves having to combine your old booster assembly with new master. Likely your booster assembly is on last leg anyway. Booster motor failure is number cause of sudden loss of brakes. Also FSM calls the brake control wire non reusable. If buying just master, you'll need new brake control wire and it's nuts and screws. That wire is very expensive by itself, but comes with booster motor w/pump or booster assembly or master w/booster assembly.

In mud guys recommend pulling lower dash molding apart. I find easier/faster to not pull dash molding.

One thing I'm very careful with, is installing hard line flare nuts. FSM recommends to oil threads of flare nut, which I do. Then thread flares on by hand. Taking time here is very important!

BTW: I use only, Toyota brake fluid these days. Not even Dealership use it. It's my hope, their fluid will take better care of seals. I flush every 2 to 3 years. I flush at least one quart through rear calipers then move to fronts.

FWIW: I'm guessing; your rear caliper where replaced, due to rusted/frozen bleeders and/or piston seal issues.

Keeping those bleeder rubber caps on, will keep bleeders from rusting in.

 

[Boss Hog]

It's not hard to replace, for me. But I've pulled many.

You can buy just master, w/out booster assembly. But best to just buy complet master w/booster assembly. Saves having to combine your old booster assembly with new master. Likely your booster assembly is on last leg anyway. Booster motor failure is number cause of sudden loss of brakes. Also FSM calls the brake control wire non reusable. If buying just master, you'll need new brake control wire and it's nuts and screws. That wire is very expensive by itself, but comes with booster motor w/pump or booster assembly or master w/booster assembly.

In mud guys recommend pulling lower dash molding apart. I find easier/faster to not pull dash molding.

One thing I'm very careful with, is installing hard line flare nuts. FSM recommends to oil threads of flare nut, which I do. Then thread flares on by hand. Taking time here is very important!

BTW: I use only, Toyota brake fluid these days. Not even Dealership use it. It's my hope, their fluid will take better care of seals. I flush every 2 to 3 years. I flush at least one quart through rear calipers then move to fronts.

FWIW: I'm guessing; your rear caliper where replaced, due to rusted/frozen bleeders and/or piston seal issues.

Keeping those bleeder rubber caps on, will keep bleeders from rusting in.

Frustrating…probably why I got such a good deal on this truck a couple of weeks ago. I got the squealing brakes fixed ASAP…and then this comes up. Good news this isn’t coming up in the mountains or on a roadtrip.

Thank you for your advice! Gonna reach out to my club for help with this one…

 

[nissanh]

Have you consider the brake booster pump motor replacement? I am currently working with my cousins Montero 2001 full size with the same brake pump issue. We took the motor out (have to pull the brake master pump out of the truck) and saw the commutator in the armature is 100% worn out. To rebuild it as eutron, going cost $265.

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[CloudCity]

So just yesterday I got new rotors, pads, and calipers (all on the rear only) and a brake flush. This am I get the dying seagull. Any chance they are related?

Was this done at a Toyota dealer? Reason I ask is because I believe the dealer did my brake flush incorrectly which caused a failure of my brake system the very next day (I have threads on here about it). At first Toyota dealer accepted responsibility then later tried to deny the claim. I have an LX so I took it to Lexus to be corrected and they also said Toyota did the flush incorrectly because they had to keep bleeding air out and adding fluid, which shows Toyota dealer left air in the system and didn't bleed properly. They also showed some codes that came up after the dealer work was done, not before. I was also seeing bubbles in the reservoir. Supposedly this made the plunger travel further than it had been with proper fluid level, so past the worn-smooth section onto a rougher area, which caused the seal to leak fluid and the pump was running somewhat "dry." That's my layman's explanation, tho my threads from a few years back (2018) may have a more specific explanation. I ended up suing the Toyota dealer for over $5k using an attorney on contingency and won that plus attorney fees.
If you feel the dealer caused this get a second opinion if possible and codes and then ask them to make a claim with their insurance first. That the easiest way to move forward. Then small claims if they refuse and you're willing, but in my case they moved it from small claims to a full jury trial (odd Oregon law) but I got an attorney on contingency and they settled prior to going to court after their attorney told them they were nuts to fight this. That's what their attorney told mine anyway. lol

 

[Boss Hog]

Was this done at a Toyota dealer? Reason I ask is because I believe the dealer did my brake flush incorrectly which caused a failure of my brake system the very next day (I have threads on here about it). At first Toyota dealer accepted responsibility then later tried to deny the claim. I have an LX so I took it to Lexus to be corrected and they also said Toyota did the flush incorrectly because they had to keep bleeding air out and adding fluid, which shows Toyota dealer left air in the system and didn't bleed properly. They also showed some codes that came up after the dealer work was done, not before. I was also seeing bubbles in the reservoir. Supposedly this made the plunger travel further than it had been with proper fluid level, so past the worn-smooth section onto a rougher area, which caused the seal to leak fluid and the pump was running somewhat "dry." That's my layman's explanation, tho my threads from a few years back (2018) may have a more specific explanation. I ended up suing the Toyota dealer for over $5k using an attorney on contingency and won that plus attorney fees.
If you feel the dealer caused this get a second opinion if possible and codes and then ask them to make a claim with their insurance first. That the easiest way to move forward. Then small claims if they refuse and you're willing, but in my case they moved it from small claims to a full jury trial (odd Oregon law) but I got an attorney on contingency and they settled prior to going to court after their attorney told them they were nuts to fight this. That's what their attorney told mine anyway. lol

Not done at a Toyota dealer. But I do have video of it happening the morning after they did the work. It looks like they didn’t follow flushing procedure and may have used wrong fluid.