Help! Brakes getting weak! (1 Viewer)

[GremlinMobile]

Posting this for a friend who has a 2002 LX470 with about 200k miles. Said that this last week, he's noticed that after starting the car, the first time he goes to press the brakes, like at the end of the driveway, there’s very little braking. He finds he has to step on it pretty hard, and then pump them a few times and then it seems to be ok.

Fluid level is normal, and so no leaks.

I asked him to count how many seconds for pressure to build after evacuating all the fluid and turning the key on. It was 35 seconds.

Any ideas? Impending doom? Is it going to give out any moment?

 

[GerLC100]

Perhaps swap fluid and get air out of the system.

 

[ace10]

Don't eff around with brake troubles.
Your friend should be having a trusted mechanic look at it ASAP.

 

[GremlinMobile]

Thanks for the responses. Bleeding air makes sense except why would air all of a sudden get in the system? It's a sealed system. And if it isn't, then wouldn't I have lost fluid?

What would a mechanic look at? Fluid level normal. Brake pads are OK. What can they check? His indie mechanic is the type to "save him money" by not doing any work until it's obvious it's needed.

 

[GremlinMobile]

As an update, my friend took his car to his independent mechanic. Mechanic didn't see anything wrong visually. He theorized that the seals on the piston aren't holding pressure anymore. Said that the only way to fix this is to replace the whole MC, which would cost about $3,000. Said to drive it some more and see if it fixes itself or gets worse. When asked if he can just refurbish the MC by changing out the seals, he said they don't do that and even if they did, they wouldn't be able to guarantee anything...

 

[Bisho]

Toyota sells a master cylinder rebuild kit for about $80. That is the fix, short of replacing the whole system. It's about a 3-4 hour job. I rebuilt mine. Its not rocket surgery.

Master Cylinder Rebuild - DIY

Order correct rebuild kit. Part number for 2000 US model w/ ATRAC is 04493-60330 [edit 6/2018 - this part number is correct for all US 100s. Checked with @beno and while online it will only be listed for 2003-2007, its correct for all US 100s.] Kit is around $50, so a bunch cheaper than...

forum.ih8mud.com

 

[GremlinMobile]

Thanks. I don't have time now to go through all 31 pages on that thread but skimming through it, kinda sounds like the seal kit alone doesn't solve all the problems with the MC. Sounds like in your case you had other symptoms altogether... Are the seals about the only thing that can be refurbished on it?

Who's the guy that rebuilds them and sells them fully refurbished?

 

[Bisho]

Thanks. I don't have time now to go through all 31 pages on that thread but skimming through it, kinda sounds like the seal kit alone doesn't solve all the problems with the MC. Sounds like in your case you had other symptoms altogether... Are the seals about the only thing that can be refurbished on it?

Who's the guy that rebuilds them and sells them fully refurbished?

There are lots of things that CAN go wrong in the assembly, and the only way to make sure everything is potentially addressed is to replace the whole assembly, which is running just north of $1100 now days, I believe. If the system needs to be pumped with the pedal to get enough pressure to build, that is a classic symptom of master cylinder seals leaking, which would be fixed with the kit referenced above. You don't need to go through that whole thread, the how to is the first page or so, IIRC.

 

[Malleus]

First, I and truly hesitate to get into this, but...a 100 series Land Cruiser, or LX470, isn't a 1968 Chevy C-10 and should never be taken to a "general" mechanic. There is too much to these trucks for someone who hasn't taken the time and put in the effort to understand the design and operation to properly diagnose any problem and perform the necessary repairs. This is precisely why everyone who has good advice to share always recommends that the Toyota factory service manual and Electrical Wiring Diagram be available and consulted BEFORE performing any repair work. I've personally been repairing Land Cruisers for over 30 years and I never do anything without opening the manuals first, even if I already know what is needed.

Second, if the brake piston seals were leaking, there would be brake fluid on the inner wheel surfaces, and probably on the ground, too. FWIW, rebuilding brake calipers is a typical repair procedure - if the mechanic can't or won't do it, he shouldn't be working on the truck.

I won't try to troubleshoot the problem from here, especially without the benefit of a lot more information, but your friend needs to find a real mechanic, preferable one who has a proven reputation for repairing Land Cruisers.

 

[efjayatee]

Don't eff around with brake troubles.
Your friend should be having a trusted mechanic look at it ASAP.

Yep...☝
Tell you buddy to shop around for more quotes. If he doesn't work on cars tell him to supply the part and pay for the labor. 4hrs should run you around $600. Non-OEM master cylinder is between $600-800.

 

[GremlinMobile]

Yep...☝
Tell you buddy to shop around for more quotes. If he doesn't work on cars tell him to supply the part and pay for the labor. 4hrs should run you around $600. Non-OEM master cylinder is between $600-800.

Are you recommending going with a non oem master cylinder? Anyone else here think that's a good idea?

His trusty mechanic also said that the "computer" would need to be reprogrammed and overall is kinda talking him out of doing the work until and unless the problem becomes significantly worse.

I tried to look around for a brand new OEM one but the prices range from 1350-2000. What's the correct part number for a 2002 LX?

 

[Bisho]

His trusty mechanic shouldn't be trusted. There is no computer reprogramming needed. You don't wait for brakes to become dangerous before you fix them. If you don't want to repair the MC you have for $80, you can also replace the entire MC assembly for $1350 using the direction in the above post and it will save you an hour of labor. Go to partsouq.com and put in the vin number. You'll get all of the parts diagrams and can find the part number. This repair is one of the easiest things you can do on the truck - its a lot easier than repacking wheel bearings. Brakes are not nearly as cosmic as some folks make them out to be.

 

[efjayatee]

Are you recommending going with a non oem master cylinder? Anyone else here think that's a good idea?

His trusty mechanic also said that the "computer" would need to be reprogrammed and overall is kinda talking him out of doing the work until and unless the problem becomes significantly worse.

I tried to look around for a brand new OEM one but the prices range from 1350-2000. What's the correct part number for a 2002 LX?

Giving your buddy an option. OEM vs aftermarket. And yes ppl have ran aftermarket to save $$. OEM is always the way to go but sometimes if you are in a pinch, aftermarket is the option.
He needs a different mechanic! There's no computer "reprograming" BS. And by advising to drive it until you really need to is God awful advise. Safety of others including himself is top priority.

 

[GremlinMobile]

His trusty mechanic shouldn't be trusted. There is no computer reprogramming needed. You don't wait for brakes to become dangerous before you fix them. If you don't want to repair the MC you have for $80, you can also replace the entire MC assembly for $1350 using the direction in the above post and it will save you an hour of labor. Go to partsouq.com and put in the vin number. You'll get all of the parts diagrams and can find the part number. This repair is one of the easiest things you can do on the truck - its a lot easier than repacking wheel bearings. Brakes are not nearly as cosmic as some folks make them out to be.

Appreciate all the responses. Thank you. I followed your advise and went to partsouq.com. Trying to make sense of all the different part numbers. Here's what they show:

BRAKE BOOSTER ASSY, W/MASTER CYLINDER. Part no. 4705060042. Costs $3,100.​

CYLINDER SUB-ASSY, BRAKE MASTER. Part no. 4702560042. Costs $1,788.​

PUMP ASSY, BRAKE BOOSTER W/ACCUMULATOR. Part no. 4707060010. Costs $996.​

When I type these part numbers in to any search engine, the same part comes up... There's no difference between the $1800 and $3000 parts. What's going on??

Again, I apologize for the noob questions. If the symptoms he's experiencing in his car point to leakage at the seals of the MC, then my understanding is part number 4702560042 is what he needs. Correct??

However, a lot of threads on this forum talk about the pump motor going bad over time due to corrosion at the terminals, among other reasons (usual electrical pump wear and tear over 20+ years). So if he's going to be doing all this work, should he replace the pump assembly too? Therefore, shouldn't he go with the full brake booster assembly for $3100?

 

[Zuberg]

Appreciate all the responses. Thank you. I followed your advise and went to partsouq.com. Trying to make sense of all the different part numbers. Here's what they show:

BRAKE BOOSTER ASSY, W/MASTER CYLINDER. Part no. 4705060042. Costs $3,100.​

CYLINDER SUB-ASSY, BRAKE MASTER. Part no. 4702560042. Costs $1,788.​

PUMP ASSY, BRAKE BOOSTER W/ACCUMULATOR. Part no. 4707060010. Costs $996.​

When I type these part numbers in to any search engine, the same part comes up... There's no difference between the $1800 and $3000 parts. What's going on??

Again, I apologize for the noob questions. If the symptoms he's experiencing in his car point to leakage at the seals of the MC, then my understanding is part number 4702560042 is what he needs. Correct??

However, a lot of threads on this forum talk about the pump motor going bad over time due to corrosion at the terminals, among other reasons (usual electrical pump wear and tear over 20+ years). So if he's going to be doing all this work, should he replace the pump assembly too? Therefore, shouldn't he go with the full brake booster assembly for $3100?

Trying to diagnose a brake issue like this, for a friend, online isn't practical. Your friend needs to take the truck to an experienced shop with competent mechanics so they can properly diagnose it. Any mechanic that recommends 'driving it to see if it gets better' when you have weak brake issue, shouldn't be in business.

Btw, it's nice of you to try to help your friend out. The best help would be to find them a good mechanic.

 

[GremlinMobile]

Trying to diagnose a brake issue like this, for a friend, online isn't practical. Your friend needs to take the truck to an experienced shop with competent mechanics so they can properly diagnose it. Any mechanic that recommends 'driving it to see if it gets better' when you have weak brake issue, shouldn't be in business.

Btw, it's nice of you to try to help your friend out. The best help would be to find them a good mechanic.

If only it was so simple. My buddy lives several hours away from me, in the city. Otherwise, I would've been more involved in the diagnosing. Also, his mechanic is actually one of his best friends for decades so it's a bit of a touchy situation as far as him going elsewhere to fix his car. The mechanic does good work but was never one to err on the side of caution...So anyway, he's going to get the work done at that mechanic one way or another. He's at the point now that he just wants to know exactly which part number is the correct one for him. But since I myself have a 2003, I'm also very curious to understand what's with the different part numbers pointing to the same assembly?

 

[Trunk Monkey]

Your top part is the whole assembly, next one is just the master, bottom one is just the booster.

 

[GremlinMobile]

Your top part is the whole assembly, next one is just the master, bottom one is just the booster.

Thanks for the reply. If you're correct, then why is it that there is no price difference between the whole assembly and just the master? Something fishy is going on with the part numbers. Try googling 4705060042

 

[Malleus]

Why would you even consider throwing parts at the truck before you know what the problem is?

As for the mechanic problem, I guess you'd rather your friend lose his brakes on the road, endangering himself and possbily others than hurt someone's feelings?

 

[GremlinMobile]

Why would you even consider throwing parts at the truck before you know what the problem is?

As for the mechanic problem, I guess you'd rather your friend lose his brakes on the road, endangering himself and possbily others than hurt someone's feelings?

Roger that - I agree. Throwing parts at it without having a definitive diagnosis is wasteful. How can you get a definitive diagnosis of worn out seals on the master cylinder piston?