A legit mechanic shop!
Help! Brakes getting weak!
- Thread starter GremlinMobile
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
Malleus
Far west of Siegen
The answer to this and all other related questions is in the Toyota service manual. There is a copy in the Resources forum that you, or anyone else, can download for free. It is written in plain English and, if you can read, you can follow the procedures and feel confiodent that you can solve almost any problem that can arise in your truck.
Malleus
Far west of Siegen
Malleus
Far west of Siegen
I understand that not everyone has the interest or means to work on their own trucks, but...these trucks will cost you a lot of money if you do not maintain them and if you're going to own an expensive truck, you should, IMHO, at least understand, to the extent that you can, what it takes to keep it running and what it takes to repair any failures that may happen.
This approach protects you from well intentioned, but unprepared, "help", as well as unscrupulous people who make it their life's work to take advantage of others.
If you're not prepared to at least educate yourself about why these trucks have such a following all over the world, you may need to reevaluate why you own one. They are not for everyone, but very little in life is.
<insert stump dismount emoji>
This approach protects you from well intentioned, but unprepared, "help", as well as unscrupulous people who make it their life's work to take advantage of others.
If you're not prepared to at least educate yourself about why these trucks have such a following all over the world, you may need to reevaluate why you own one. They are not for everyone, but very little in life is.
<insert stump dismount emoji>
Upping his car insurance liability limits seems like an appropriate course of action.
This is totally nuts.
This is totally nuts.
- Thread starter
- #26
Still - your suggestion is to diagnose the problem. Ok, all roads point to the MC. How do you diagnose it - short of taking it out and breaking it apart and looking at the orings? Most people on this forum would agree that going that deep into it is dangerous and best left to the pros. So if he takes it to a "reputable" shop, to put in all the labor of taking the MC out and breaking it apart only to diagnose it, he would be well advised to just have them install a new MC in the time it will take them to do all this work. Hence, "throwing a new part at it" would likely be the solution. Right?
Malleus
Far west of Siegen
Why are you certain that you need to "break it apart" to diagnose it? I gave you the tools to do the work. You're there, I'm not.
Malleus
Far west of Siegen
Malleus
Far west of Siegen
Malleus
Far west of Siegen
Malleus
Far west of Siegen
Malleus
Far west of Siegen
Malleus
Far west of Siegen
Malleus
Far west of Siegen
HTH
- Thread starter
- #35
Appreciate you taking the time to post that. I've been looking through the FSM myself. So, like I asked earlier, if no fluid leaks were observed, then there can be no air leak, right? Because if the cause of this issue is air in the system, then that means the system isn't sealed and has a leak and therefore there should be fluid leakage somewhere. There isn't,, and the reservoir is full.
So if that rules out the air in system/fluid leak causes, then the other two potential causes are worn piston seals or failed motor, either of which point to replacing the assembly. Right?
So if that rules out the air in system/fluid leak causes, then the other two potential causes are worn piston seals or failed motor, either of which point to replacing the assembly. Right?
Worth asking: is the brake fluid dirty? Try flushing it 1st?
@GremlinMobile - you're on the right track here, as far as your thinking.
The brake system's electric motor on my '99 LX failed at 309K (commutator was fried due to worn out brushes), and I just decided that the $1300 fix (new assembly). I installed it in ~1 hour and my wife helped me bleed it. I got the dashboard alarm horn and failure with zero warning.
Here's the list of stuff that is handily included in the expensive 'assembly' - the motor and pump, the accumulator, the brake master cylinder, and all (rusty) wiring.
<philosophic note>
If you read the bajillion brake threads on Mud, you'll find that people will often replace the one component that failed (the accumulator or motor) only to find that the 'next thing' (master cylinder) failed 6 months later. By throwing money at it, I have (we hope) removed any brake system failures (other than calipers) for the life of the truck.
Yes, it's expensive, but so is screwing around with brakes in time, money, and possible accidents. I'm cheap by nature, but in this case, replacing all the old/tired/worn brake parts with OEM/new in one pass seemed right - especially at 300K+ miles. Every part of owning an LX can be expensive, and that's just the way it is.
<end philosophic note>
The brake system's electric motor on my '99 LX failed at 309K (commutator was fried due to worn out brushes), and I just decided that the $1300 fix (new assembly). I installed it in ~1 hour and my wife helped me bleed it. I got the dashboard alarm horn and failure with zero warning.
Here's the list of stuff that is handily included in the expensive 'assembly' - the motor and pump, the accumulator, the brake master cylinder, and all (rusty) wiring.
<philosophic note>
If you read the bajillion brake threads on Mud, you'll find that people will often replace the one component that failed (the accumulator or motor) only to find that the 'next thing' (master cylinder) failed 6 months later. By throwing money at it, I have (we hope) removed any brake system failures (other than calipers) for the life of the truck.
Yes, it's expensive, but so is screwing around with brakes in time, money, and possible accidents. I'm cheap by nature, but in this case, replacing all the old/tired/worn brake parts with OEM/new in one pass seemed right - especially at 300K+ miles. Every part of owning an LX can be expensive, and that's just the way it is.
<end philosophic note>
- Thread starter
- #38
That makes sense. I was thinking along the same lines. That main thread where the one guy warns about corrosion on the terminals causing excessive amp draw by the motor - frying it and causing catastrophic brake failure only explains part of the failure of these systems. Seems like the other failure point, among others, is the worn seals. So people recommending replacing the MC aren't taking into account the electric motor failing, and vice versa. Hence me trying to make sense of the part numbers. Partsouq gives two different part numbers which show a $3000 part and a $1700 part. When I look elsewhere, both part numbers seem to be for the same thing - the whole assembly with everything included. I just want to know what we're getting to make sure it includes everything.
RE: part numbers - I called my local Lexus dealer and gave them my VIN to get the 'for sure' part number for my truck, and then ordered it from the Toyota dealer at a huge savings (because I know the guys there). The Lexus dealer wanted $300+ more for the part.
I would not order from Partsouq (or some place where it's difficult to return it) unless you're darn sure about the part number. I think your truck may take a different part than mine. Reply 12 here tells my brake booster replacement story and shows the fried motor commutator. New 100 owner, long time cruiserhead - https://forum.ih8mud.com/threads/new-100-owner-long-time-cruiserhead.1300238/
I would not order from Partsouq (or some place where it's difficult to return it) unless you're darn sure about the part number. I think your truck may take a different part than mine. Reply 12 here tells my brake booster replacement story and shows the fried motor commutator. New 100 owner, long time cruiserhead - https://forum.ih8mud.com/threads/new-100-owner-long-time-cruiserhead.1300238/
Malleus
Far west of Siegen
You are welcome. In theory, yes, if there are no leaks there should be no air in the system, if it hasn't been opened (for example, if the brake bleed screw hasn't been loosened). However, air molecules are very, very small and you acutally need a leak testing machine (which introduces a marking gas into the system and then looks for it) to determine if a leak exists and where the leak is. I used this system when I worked for an automotive supplier building off road axles, and they aren't pressurized; pressurized systems, even very low pressure systems, are much more susceptible to leaks.
The first step is to actually follow the steps in the manual for inspection. Brake fluid should be changed yearly. If the fluid in the failing system hasn't been replaced, it should be changed before any troubleshooting is performed. Then, the system shoud be bled. Only after this can you actually start to look for root causes.
A very skilled technician, or someone very familiar with Toyota systems and this problem truck specifically, may be able to skip steps, but that is the exception, not the rule.
It may seem easier to just replace parts, and dealerships do this because it's more profitable for them to sell parts (that's how they make money) and it's quicker than troubleshooting, but it isn't beneficial in the long run, because you never know what really failed. Since you don't really know, you can't prepare for the future, and you're embarking on a long-term parts replacing effort. That's fine if you're restoring a truck or just have a lot of money, but it's foolhardy otherwise.
Once you have positively identified the root cause, do proceed with any quick fixes that have been proven for resolving that/those conditions. Remember this: you can't successfully solve a problem you haven't identified.
