Yota Folks ....HELP

mysterync

Well-Known Member
Joined
Feb 22, 2008
Location
boone nc
Alright guys....Before anyone says anything keep this in mind...
We're a full service shop, We fix 30 + Vehicles a week...probably 15 brake jobs a week...With ASE Techs and everything so we'll skip the basics lol


I've got a T100 95 model in the shop...
Bad master Cylinder... or so we thought causing random pedal loss.
Replaced it, Power Bled everything, Manually bled everything..Bench bled the MC , bled the rear Prop. Valve,

Still no pedal, All wheel cyl. are fine, Calipers are fine, Checked all rubber hoses and checked all divider blocks for leaks, Rebled the MC and all the system , Have flow but not pressure, Tried another MC and went through it again...Same results?

Any Ideas?
 
Brakes

Toyotas can be a pain in the Butt to Blead the Brakes--------
Just went threw same thing with my 84----------Everything U have stated--------Try opening up the Bledders and let Them gravety Bleed for a while---------
Thats what I had to do ---yes sounds Crazy------But works
 
Air is still in system. I bleed pass front, driver front, pass rear driver rear. Between front and rear, I bleed any propo valve in system. Is MC clearance between rod and mc plunger set per instructions? If not, pissing in the wind. Do you have ABS? Never been a problem for me but may be for T. I use vacuum pump and have always had excellent results after MC pin to plunger clearance was set correctly during initial install.

MY $0.02
 
I have had random pedal loos caused by a bad (very) wheel bearing. I guess it wobbled so much it pushed the pad into the caliper, and it acted like when you put new pads in and you gotta pump the brakes once or twice or they go to the floor. (maybe?)
 
Wheel Bearings are fine, I always start at the farthest point, But have tried front first as well! I've used a Mity Vac, a Pressure Bleeder, a hand pump, and manually!
Pushrod is set to exact spec with the Yota tool, I'll try a gravity bleed, I've put the pressure set on the master Cyl. and its within spec as well, No ABS. All valves & T's have been bled! Also , Its got fresh clean fluid at every point, no bubbles.
My only other thought would be a T leaking, or I've missed a hose thats allowing expansion but i dont think so. I cant even get pressure if I clamp the rubber hoses off.
All thats left is a big air bubble some where, or a leak.
 
I've had a problem on more than one occasion of aftermarket master cylinder plunger depths and stock settings on the pushrods. If it won't let the plunger release far enough it won't let it gain fluid to release the vacuum and push pressure...
Usually it's identified by poor flow when trying to bleed...but I think you said you're good there...so I guess what I'm trying to say...is that I have no idea...

How much for a vp44?
 
Hahaha

Geee thanks will!

I've got a buddy with a HR pretty cheap, Cheaper than I pay for a new SO pump.
call me monday...Me , Pederson and Schwager are going to work monday..The old lady is the only one taking off....Go figure!
 
or another bad master cyl.

Where are you getting you parts ?

I've had it happen even from Carquest, repeated bad parts, AZ and AA seem to be worse about it.

was working on a Nissan truck and went thru 4 master cyls till I finally got one that would work. 2 of then had scoring on the sealing taper where the line threaded in, allowed it to pump up, but wouldn't hold prsssure, the third had a small gouge in the inner bore and was allowing fluid to bypass, the foutrh ( from a different parts store ) actually worked.

The quality of reman parts has gone in the shitter the last few year. I buy new now, when I can, just because of this. I find many after market parts aren't worth the metal they are cast from either.
 
with master cylinder installed on vehicle remove lines, take some old line fittings and solder them up screw those into the MC and see if you have a pedal should be hard as a rock, you could have a bad new MC and if its the second one installed another bad one it. Shit happens, if you block master cylinder ports as described you eliminate everything before it, (rod position, MC), and you can move on. i would skip the T and go to abs unit block those w/ your fittings, i have seen the ABS units loose pressure in some foreign pass. cars. rare but possible. masters bench bleed but can leak internally under pressure on vehicle.

this method works for an accurate diagnosis as well. If anything comes in with loss of brake pedal I always block the ports on master and see if it holds pressure.
 
I thought that as well, Pressure tested it, It's within spec
thanks for the help though! :beer::beer:
Ya'll dont forget Dyno day is coming up!
 
PS,
CPerry,
We're working on 2 project trucks, Both will be 1,000-1,500 +RWHP.
One will be a sled puller, One will be a Drag Truck.. It will be a while before its needed but if you think you can help me on the Gear train , get up with me!

L
 
okay so move on, move down the system, there is also the proportioning valve on the frame in the rear. you have to eliminate the part of the system that is letting the pressure bleed out. by blocking off and eliminating sections of it at a time.
 
have you adjusted the rear shoes ?

My Runner I would have to double some time triple pump to get the pedal hard, then have to do it again the next stop. adjusted the rear brakes ( and fixed the parking brake cable so they would adjust the way they were supposed to ) never had an issue again.

Just another suggestion .
 
this is like a chat room...........

by the way pressure tester is way advanced i got to get one of those.

And ya we can help you on the gears the high nickel alloy R&P's can handle anything.
 
Yea, i've tested it most of the way back..It just sucks, a job that pays 1.5 is taking 4, I'll be honest, I'm trying to get out of it the quick way...at hour 4, I was so Mad and covered in brake fluid i said the heck with it. Yea, a pressure tester is way advanced...if your talking about price...I think i'm going to trade some tools on a modis and quit working on old vehicles. Heck you can get a pressure modulator to test brake systems as well!

Cperry, Do you do complete setups? I would really like to have somthing ready to bolt in, I understand if you dont do that!
 
oh ya I do complete set ups...........

4 hours I have had a couple day cars where it only pays an hour, honestly soemtimes you just have to walk away from stuff and let soemone else look at it. I have a good buddy that we trade stupid shit like this, for some reason it doesn't make you as pissed when you are doing it for a buddy and not to make a living.
 
Awsome! I'll try some more trouble shooting in the moring, I've found after a long day, If i cant solve somthing to take a step back and re evaluate!
 
What about the vacuum power booster? Is it possible it has an internal leak?

Can the random loss be replicated w/ the vehicle off, or only when it's on?
 
Thats the Screwy thing,
It passes it's air tight test, and Works with vehicle running, but the problem isnt MC related, It works fine on or off the vehicle..

The long and short of it, is im missing somthing... Its a simple system and it works or it dosent ......Its just figuring out what i missed! lol
 
I was going to say the rear pp valve...Had problems with mine, and also had problems with the return recycling line on my 4runner...Not sure if the T100 has a return line or not...
 
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