Brake system advice

My son and I replaced the front brake calipers with a power stop set. We went with the larger caliper after studying threads on this forum. One of the lines broke so we got air in the system. Tried a 2 man bleed for an hour using a bleed buddy. Could only get a small dribble from the rear lines but no air. Barely got a few drops to push through the new front calipers. But I can see the fluid I put in the bleed buddy moving on pedal stroke. After an hour I figure something isn't right. Double checked the calipers are on the correct sides and vents are on top. Very slightly cracked the master cylinder line connection nearest the firewall and when he hit the pedal it was a very strong spray. Went and bought a vacuum pump to try and speed things up. I'm pulling negative 15 to negative 20. On the front two I get nothing but air bleed down. I went to the proportion valve vent in the back. I pulled negative 20 on it cracked wide open and it sat there rock sold vacuum and just held. Nothing came out and nothing bled down. Is it possible the proportion valve became stuck? I'm thinking something should come out of the vent and bleed down under vacuum. Hell shouldn't fluid come out even without vacuum? Thanks for any advice. I've never had this much trouble bleeding brakes in over 30 years of working on trucks.

 

Could be corrosion blocking a hard or soft line.

 

I had to Google Bleed Buddy... I've never seen one of those. The job it does is usually accomplished with a piece of 2x4 and sliding the seat forward. Are you trying to suck fluid out of the calipers with the Bleed Buddy in place? Cause that's not going to work. When the brake pedal is pressed you're going to get one "pump's worth" of flow, then the system is sealed. That Bleed Buddy would have helped if you put it in place before you removed the calipers -- because it would have sealed the system and kept fluid from constantly dripping out while the line was open. Did the reservoir run low while you had the calipers and line off?

 

My "bleed buddy" is just the cup with vent and hose that you can use to bleed the brakes by yourself. The reservoir did not go empty, but it was low

 

Got it. When I searched Bleed Buddy, I got this contraption.

 

I can’t explain this unfortunately, sounds almost like something is clogged/jammed but the only place that makes sense is it’d be a jam in the LSPV or line to the LSPV, but the LSPV makes the most sense. But …. Two wildly important things here.

Put a 2x4 or something on the floor, do NOT let the kid push the pedal to the floor or you will blow out a seal (if not already done, and it’s part of the problem). You don’t want to pay for a replacement MC, and the quality function of aftermarket is garbage on these trucks.

Depending on which vacuum system you’re using, sometimes the fittings don’t slip over the bleeder so well, and will result in air bubbles showing in the line.

I guess the more concerning thing that threw a red flag to me here is “line broke”. Are you in the rust belt, by chance? If yes, have you thoroughly inspected all the lines? Secondarily, are you sure the frame is OK?

 

Thanks for the suggestions. Yes I'm in the rust belt. The frame must have been replaced it looks brand new. I bought the truck because the frame was so good. Can't say the same for my old FJ cruiser. The brake lines look like they were replaced with the frame for the most part. The last section between the caliper and the fitting near the strut tower is what broke. They were steel not rubber. Driver side was recently replaced. Passenger side was very corroded. I let penetrant soak in and heated it with a torch before turning it but as it started to turn the line snapped like a twig.
The kid definitely put the pedal to the floor more than once but the MC still seems to be putting out pressure. I'm just thinking that proportion valve has to be part of the issue. I can't imagine why I'm able to hold a solid vacuum on it. It should leak down under vacuum. I didn't have someone to push the pedal in while I pulled vacuum on it. I'll try that as one last ditch effort. If it still holds vacuum and doesn't bleed I'll replace the valve first before throwing a new MC at it. It's just weird. I'm thinking that valve must be stopping the fluid from bleeding down through the rest of the system.

 

How are you bleeding it? Truck on the ground or axle supported on Jack stands? If the axle is drooping you won't get any fluid out of the lines. It's probably corroded, but just throwing that out there.

 

Originally the front was on stands and the rear was on the tires. The next day I had all four wheels back on.

 

I wouldn't be able to help myself and would want to nip things in the bud, with one of two things, if you're not getting anything to the left/right drum because that suggests obstruction between the MC and LSPV:

1. I'd stop everything and try reverse-bleeding from the, because it sounds like you've got something jammed in the line feeding the LSPV, but be aware, if truck is ABS, that same blockage may jam up your ABS squid, which is more expensive... in light of that, maybe another option like...
2. pull/hold 15-20 vacuum on the LSPV and crack its bleeder; if nothing came out more than a dribble, I'd feel compelled to pop the hard line off the LSPV on the cab side of things, and plug it momentarily, then find a fitting to throw a vacuum directly on the hard line itself and see what I got, and if "nothing", you know it's farther upstream which would either put it in the ABS squid

Think about this from a logical perspective, tackle the elephant in the room: You're getting nothing to the rear drums. What would cause that? Think about the logical roadblocks here, and test theories that could be related. It sounds to me like you have trash in your lines.

 

Unfortunately, it appears the master cylinder for 2000-06 Regular Cab & Access Cab w/o VSC is NLA from Toyota. Looks like aftermarket is the only option. Tried ordering one for a 2003 recently and was given this news.

Part numbers 472010C010 (old), 472010C011 (old), 472010C012 (most recent)

 

Ooof. I remember there were a few made, and you couldn't buy the MC alone, but they were still selling the MC+booster combo as a whole unit, north of $1k.

To your point though, I'm curious about two things on @Truckrescue's truck:

• Does the truck have ABS, i.e. ABS squid is sitting between the power steering reservoir and firewall on passenger side?
• Do the non-ABS and/or earlier-model trucks have a single line/single bowl out to the brakes, or is it direct lines to each front, then another direct line to the rear

Trying to workflow through the possibilities on fluid passages. I haven't seen any pics of OP's brake stuff under-hood.

 

I don't think I have ABS. Do you have a picture of the squid? I can pull the inlet line to the LSPV and try vacuum from the cab side line like you note. Do you happen to have a picture or diagram so I know which line it is or just trace it back? Seems like multiple lines head back to it but I didn't follow them the entire length

 

It'd also be interesting to know how many/what lines are coming off your MC. This is an old picture, prior to full fluid flush on my end. Also an '06 so it'll look less cluttered than yours due to missing EVAP canister etc.

 

Thanks for the picture. I do not have the abs module on the passenger side. Pretty sure the MC only has two lines. But if I recall there is a tee right below it. I'll get some pictures after work. And I'll try to figure out which line feeds into LSPV and try to pull vacuum between it and MC. If I'm getting fluid there it's got to be something with the LSPV.

 

That's my thought process, really. Hopefully it's not something stupid, like you jacked up on a line or a line is pinched. Although I may very well prefer that versus random mystery crap floating in the lines!

 

The lines all look like new except for the crappie piece that broke right at the caliper

 

So if have good pressure when pressing the pedal at the master cylinder where it connects to the first hard line, could you then tighten that back up and crack the next fitting down to see if you still have or lose pressure when pressing the pedal? Could repeat at the next fitting and continue until lose pressure. Seems that would isolate the problem to a particular section. Then could crack open both sides and test flow through that section (assuming it's not straddling the ABS to avoid pushing any particles through the ABS as @shifty' mentioned) and if clogged, clear it or replace it. By the way haven't experienced this on a Bestgen Tundra but have on a 70s LC. Soft line can deteriorate inside and clog. Might start there testing right before and right after the softline. But sounds like you also seem to have evidence of rust in the hard line? How's the fluid look that does come out ... just dark and old looking ... or containing rust particles?

 

I haven't had time to mess with it this week but that's a good suggestion. The only rusted line I found was the last 5 inches connected to the caliper. Everything else looks new. The fluid looked clean and clear coming out. The LSPV looks old rusty and original. Not sure why they would have replaced all the lines except for those two. Good times.