Master Cylinder Rebuild - DIY (2 Viewers)
- Thread starter Skidoo
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Gonna watch it I guess for a day or so. Pedal feels fine
A little over the max fill line shouldn't be causing the leak. Has anything been done to the MC recently - or hit/smashed while working on something else under the hood? The reservoir is held down by three screws and has three openings that insert into the MC assembly with corresponding o-ring/gaskets. Any way those could have been disturbed?
scott thanks for the info no real work done in that area; did some ruff snow/offroad stuff but nothing crazy; I did check those screws you mentioned! all good re tightened but not to tight 
re did the lid and also took some fluid out so now I'm just at the top of max line. did little bit of driving and all seems good; i believe the leak stopped. I really think it was the cap!!! Now this revisoir gets pressurized when in heavy use some maybe out of the cap??? no really sure. I have a trip to NYC friday so I hope all goes good; should get lots of bumper to bumper driving to test out the system. LOL will keep cell phone close in case I have to call tow truck
re did the lid and also took some fluid out so now I'm just at the top of max line. did little bit of driving and all seems good; i believe the leak stopped. I really think it was the cap!!! Now this revisoir gets pressurized when in heavy use some maybe out of the cap??? no really sure. I have a trip to NYC friday so I hope all goes good; should get lots of bumper to bumper driving to test out the system. LOL will keep cell phone close in case I have to call tow truck
Excellent Instructional post!
I followed this and rebuilt the master cylinder in my 99 lx470.
Got my full brake pedal back, after years of double pumping to slow down when hauling the boat.
Spent more time bleeding brakes than anything else.
Easy fix, don't be scared - just follow the pics and instructions.
I followed this and rebuilt the master cylinder in my 99 lx470.
Got my full brake pedal back, after years of double pumping to slow down when hauling the boat.
Spent more time bleeding brakes than anything else.
Easy fix, don't be scared - just follow the pics and instructions.
Did this a couple of weeks back on a 00, no issues what so ever, full pedal resistance again. The write up was excellent. Replaced the rear calipers as well. Testing with extremely hard braking it was actually fun to hear chirps coming from the tires again.
These were awesome instructions and really helped speed the process up! Thanks Skidoo! I just did this last night to my '99 LX470 and i now have some serious stopping power! I had no idea this truck had brakes like this...I just assumed it was heavy and the brakes weren't very good. I've had the spongy pedal since I bought the truck in March. The pedal needs to be depressed 1.5-2" before I get any brakes. Another tell tale sign that it is your master cylinder is when you are at a light and have the pedal depressed, you can slightly pump the brake pedal and get the pedal to climb up to the top of it's travel. You will also then have brakes at the top of the pedal travel. This quickly dissipates after driving.
A couple things:
-Bleed the master cylinder on the bench before installing it and hooking up brake lines. It makes bleeding the system so much easier. To do this, after reassembling the master cylinder and re-attaching the brake fluid reservoir, add fluid to the reservoir up to the max line. Push and pull the master cylinder in and out (about 1" stroke) until you have good clean fluid flowing out of the holes where the brake lines connect. If you put your fingers over the holes you should be able to feel the bubbles "spitting" out of the holes. Once that stops you are good to go. This made for a simple and quick (20 minutes) brake bleed.
-It took a lot of force to get the plunger out of the assembly. I ended up pushing the plunger in as far as I could and then pulled (by hand) with lots of force. Since the clevis was about .5" from the opening of the bore, the momentum of the clevis helped get the plunger out. I used enough force that I was scared I may have scored the bore, but luckily, the bore was perfect!
If you have a spongy pedal, do this now! $50 and 3 hours of work is much better than spending thousands on a new pump, or loosing your brakes and crashing the truck.
I got my master cylinder piston kit from cruiserdan shipped to my door for about $60. Quick shipping and everything needed to do this job. Good luck!
A couple things:
-Bleed the master cylinder on the bench before installing it and hooking up brake lines. It makes bleeding the system so much easier. To do this, after reassembling the master cylinder and re-attaching the brake fluid reservoir, add fluid to the reservoir up to the max line. Push and pull the master cylinder in and out (about 1" stroke) until you have good clean fluid flowing out of the holes where the brake lines connect. If you put your fingers over the holes you should be able to feel the bubbles "spitting" out of the holes. Once that stops you are good to go. This made for a simple and quick (20 minutes) brake bleed.
-It took a lot of force to get the plunger out of the assembly. I ended up pushing the plunger in as far as I could and then pulled (by hand) with lots of force. Since the clevis was about .5" from the opening of the bore, the momentum of the clevis helped get the plunger out. I used enough force that I was scared I may have scored the bore, but luckily, the bore was perfect!
If you have a spongy pedal, do this now! $50 and 3 hours of work is much better than spending thousands on a new pump, or loosing your brakes and crashing the truck.
I got my master cylinder piston kit from cruiserdan shipped to my door for about $60. Quick shipping and everything needed to do this job. Good luck!
So this thread was extremely helpful and I replaced my master cylinder piston kit, unfortunately mine did not work. The brake light and beeping noise still still exists. I am throwing codes that state my brake booster pump is failing. My Toyota dealership sells them for $1,500. I was fortunate to find a salvage yard that could get one to me in a few days for $300. My question is has anyone ever changed just the brake booster pump?
I did that exact thing - swapped out just the brake booster. There are a few model years of 4runners that used the same booster but a different master cylinder. Once I found that it was easy to locate a booster. Iirc, I paid $200 delivered for one out of a wrecked 4runner with 90k or so. Combined with a set of power stop brakes and rotors went from scary to fantastic.
@Scottb4857 how hard is it just to replace the brake booster? Do u still have to bleed?
Once you get the entire assembly out if the vehicle it is just a few bolts and screws to change the booster out. I would make sure to use a good set of flare nut wrenches on the brake lines so you don't mess up the nuts. Yes, you most definitely need to bleed the entire system when swapping the booster.
Could be one of the three little rubber washers/seals that seal the reservoir to the master cylinder. They are just push-on. You have to remove the master cylinder to get to them.
Great thread I hope that after all this time a few are still monitoring it.
99 LC - I have normal braking until it's below 25 or so deg outside I get the ABS alarm until the LC fully warms up interior and engine so that can take an hour. I'm going deaf from that alarm.
1. Has anyone else ever had the ABS alarm only go off in freezing temps?
2. Is there a chance the system simply has too much water in it and that's what's freezing in the system causing the alarm?
I have a hate/hate relationship with messy brake fluid so I'm trying to justify just taking it to a shop for a full fluid clean out or should I just rebuild the MC and stop finding reasons to avoid the job? Also I can only find the rebuild kit for $60+shipping any leads on lower priced deals would be appreciated.
99 LC - I have normal braking until it's below 25 or so deg outside I get the ABS alarm until the LC fully warms up interior and engine so that can take an hour. I'm going deaf from that alarm.
1. Has anyone else ever had the ABS alarm only go off in freezing temps?
2. Is there a chance the system simply has too much water in it and that's what's freezing in the system causing the alarm?
I have a hate/hate relationship with messy brake fluid so I'm trying to justify just taking it to a shop for a full fluid clean out or should I just rebuild the MC and stop finding reasons to avoid the job? Also I can only find the rebuild kit for $60+shipping any leads on lower priced deals would be appreciated.
First, thanks Skidoo. Please pm or post your paypal address. Writeups are a pita to make and post so in my humble opinion, a few bones thrown your way by anyone who has been helped would be well deserved. And would encourage future writeups by you and others.
Eliot: Do you remember how many times you hand pumped your MC for the bench bleed? I've got the new piston in and the reservoir full and I've pumped over 60 times with just the smallest amount of fluid coming out of one of the holes. It is surely not pushing the fluid yet for some reason and the apparent fluid level isn't changing. Should I just keep going? I've tried covering two of the holes so fluid will just come out the third; no go. I was very careful to not let dirt in during the procedure and everything looked clean as I put the reservoir back on.
Edit: I tried pumping at different angles. Still nothing but some drips here and there. It's like the piston is just sucking air in and out.
Notes for future efforts:
- A hammer didn't help with my piston. After some pretty good taps I figured out that it was just pushing back so the trick was to hold it back by hand while popping the retaining clip out. I did everything alone with no issue. I used a wood block under the heavy side to keep it balanced.
- After pulling the MC assembly I didn't remove anything besides the reservoir. Easy-peasy.
My issue: I have a soft pedal that wouldn't really engage the brakes until about an inch or more into the travel. I have no reference point as to how well these trucks can stop besides my own and it's been like this since I bought it a few years ago. I think the old (bad) piston design is bleeding the pressure causing the pump to work every time I touch the brake pedal (I can hear it).
Thanks.
Phat-
Eliot: Do you remember how many times you hand pumped your MC for the bench bleed? I've got the new piston in and the reservoir full and I've pumped over 60 times with just the smallest amount of fluid coming out of one of the holes. It is surely not pushing the fluid yet for some reason and the apparent fluid level isn't changing. Should I just keep going? I've tried covering two of the holes so fluid will just come out the third; no go. I was very careful to not let dirt in during the procedure and everything looked clean as I put the reservoir back on.
Edit: I tried pumping at different angles. Still nothing but some drips here and there. It's like the piston is just sucking air in and out.
Notes for future efforts:
- A hammer didn't help with my piston. After some pretty good taps I figured out that it was just pushing back so the trick was to hold it back by hand while popping the retaining clip out. I did everything alone with no issue. I used a wood block under the heavy side to keep it balanced.
- After pulling the MC assembly I didn't remove anything besides the reservoir. Easy-peasy.
My issue: I have a soft pedal that wouldn't really engage the brakes until about an inch or more into the travel. I have no reference point as to how well these trucks can stop besides my own and it's been like this since I bought it a few years ago. I think the old (bad) piston design is bleeding the pressure causing the pump to work every time I touch the brake pedal (I can hear it).
Thanks.
Phat-
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The only other way I see it being cheaper is if you can source new O-rings for the piston. The $60 kit you're buying includes the piston. From what I saw, my piston was just fine, it was just the o-rings on the piston that needed to be replaced.
I pumped probably 80-100 times. Make sure you're getting a good 1/2 inch of travel out of the piston on each pump. When pumping, the reservoir needs to be attached and filled with brake fluid. Also, ensure that the entire assembly is in the upright position so that gravity will feed fluid to the piston. This is just a bench bleed that helps speed up the brake bleeding process. Regardless of how you do it, you'll get air in the lines when you reattach the brake lines to the MC assembly. I would just get it to the point where you're squirting fluid out when pumping the piston. The rest of the air will come out when do the required brake bleeding process.
Eliot, you are the man. Thank you. I'll get this over with today.
For perspective to those trying to find this part for the best price, I paid 195.47 euros for the piston over here in the land of the great white flag. Life is short; just hit up CruiserDan or whoever and be done with it.
Please note that while bad rings will obviously compromise function, I think it's changing to the new part design that makes the difference. It better: My old piston had perfect o-rings and an intact plastic split-ring. --- Will edit with result here >......................<
Check out the picture of the two pistons together. Just as I noticed with mine, they are different. As we are dealing with hydraulics, small changes can make all the difference. There are a few places with small changes in the design so make sure you get a new one.
For perspective to those trying to find this part for the best price, I paid 195.47 euros for the piston over here in the land of the great white flag. Life is short; just hit up CruiserDan or whoever and be done with it.
Please note that while bad rings will obviously compromise function, I think it's changing to the new part design that makes the difference. It better: My old piston had perfect o-rings and an intact plastic split-ring. --- Will edit with result here >......................<
Check out the picture of the two pistons together. Just as I noticed with mine, they are different. As we are dealing with hydraulics, small changes can make all the difference. There are a few places with small changes in the design so make sure you get a new one.
alright guys, this is all great info! but im not exactly a DIY mechanic; heres my issue. Ive got a 99 100 series and almost every time i press the brakes i here this weird electric motorized whine...not to mention my brakes are pretty damn hard to press to the ground. from everything ive read here it sounds like my brake booster is failing though ive had no lights come up on the dash or anything...
Im all about keeping my 100 OEM and I just looked for a brake booster OEM replacement from an online yoto dealer and it was some $1400 after shipping just for the part. My question is this: is it worth buying the OEM replacement and have the piece of mind that my primary components of my brakes should be legit for a while? Or should i find somebody who could attempt a rebuild? I just have no idea who could do that since im not willing to do it myself.
Keep in mind that i just replaced my rotors/pads drums/liners and brake fluid some 6-7k miles ago.
from everything ive read here it sounds like my brake booster is failing though ive had no lights come up on the dash or anything...Im all about keeping my 100 OEM and I just looked for a brake booster OEM replacement from an online yoto dealer and it was some $1400 after shipping just for the part. My question is this: is it worth buying the OEM replacement and have the piece of mind that my primary components of my brakes should be legit for a while? Or should i find somebody who could attempt a rebuild? I just have no idea who could do that since im not willing to do it myself.
Keep in mind that i just replaced my rotors/pads drums/liners and brake fluid some 6-7k miles ago.
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