no brakes at all

[honeybadger]

stored my 1984 2wd 5 spd van for a year. when i came to get it it started up without issue, but the brakes go to the floor with no stopping power. i tried bleeding them and adding fluid but i barely helped at all. I'm not sure where to start can someone point me in the right direction?

[brentlehr]

Is the reservoir holding fluid? Bleeding until no air and all bleeding valves are operational?

If so then you either have a leak or the master cylinder is shot. Check you rubber lines at each wheel and for signs of brake fluid leakage as well as the front calibers and rear cylinders. Hydraulics are pretty straight forward in that it's a sealed system.

If it is the master cylinder I've never had to replace one on a TV so hopefully someone can provide more detail.

[honeybadger]

Ok so I think it's the master brake cylinder. I w as able to shove me phone up in there and take a video. These are some screenshots of that video. This part has a bunch of what looks like rust and brake fluid at the back of it. Where can I find a replacement part and how do I access it to replace it.

[Rufus]

I am going to be replacing my master cylinder on my 1985 this weekend and I will post lots of pictures and a step by step process. I said I would do that for the manual transmission replacement on my 86 and I have not yet done that but it is coming!

[Rufus]

You can order a new brake master cylinder on www.rockauto.com
The price varies from about $32 to $92 plus shipping.

[honeybadger]

Is that what I'm seeing in these photos? It doesn't look like the master brake cylinders in the photos.

[honeybadger]

Ok I ordered another brake booster. The brakes work if I put fluid in and bleed the lines but they're weak and dangerous to cruise on. So I figured the booster is bad. Now if I can figure out how to get to it and remove the existing I'll be in business.

[Rufus]

You should buy the factory service manual for your year of van. They can be had on ebay rather reasonably. You will need to remove the instrument cluster and vents from the drivers side of the van.

I see you are in Dallas. I am going to be in Dallas/Ft. Worth from March 27th to April 16 for Bell 205 factory school and if you need a hand in the afternoons when I am out of school I would be glad to help.

[timsrv]

You should also try the search feature (upper right corner of all forum pages). I typed in "Master Cylinder" and got lots of great information....probably more and better than the manual will give you. Here's a few of the better ones:

http://www.toyotavantech.com/forum/showthread.php?1550-Installing-a-New-Brake-Master-Cylinder&highlight=master+cylinder

http://www.toyotavantech.com/forum/showthread.php?1057-Master-cylinder-help&highlight=master+cylinder

http://www.toyotavantech.com/forum/showthread.php?63-How-to-Remove-the-Dashboard&highlight=master+cylinder

[brentlehr]

Here's what the manual says about testing the brake booster. Might want to try this before replacing it.

OPERATIONAL TEST OF BRAKE BOOSTER
NOTE: If the booster leaks or lacks vacuum, repair
before testing.


1. OPERATING CHECK
(a) Depress the brake pedal several times with the
engine off, and check that there is no change in the
pedal reserve distance. .
(b) Depress the brake pedal and start the engine. If the
pedal goes down slightly, operation is normal.


2. AIR TIGHTNESS
(a) Start the engine and stop it after one or two minutes.
Depress the brake pedal several times slowly. If the
pedal goes fartherest down the first time, and gradually
rises after the second or third time, the booster
is air tight.

(b) Depress the brake pedal while the engine is running,
and stop it with the pedal depressed. If there is no
change in pedal reserve travel after holding the pedal
for thirty seconds, the booster is air tight.

[honeybadger]

Master cylinder came out easy enough but I'm having trouble removing the booster. Any tips? It's hell for a big man in there.

[timsrv]

Why would you remove the booster.........did it fail too?

[Burntboot]

HB - Boosters practically never fail, when they do, the result is usually a massive vacuum leak from a breached diaphragm.
Check valves can go too (also very rare), but there are simple tests to rule both of these out (see Brenthlehr's post above)

After having been sitting for a year, I would be more inclined to do a full brake service then bleed the brakes again (don't forget about the 5th bleeder screw).
Nothing like seized callipers/sliders to make the brakes seem ineffective.
BB

[honeybadger]

I decided to put my new cylinder on and test it and you are correct, the booster is fine. So my new question is:
Anyone want to buy a new brake boster for a 1984 van let haha

[timsrv]

HB - Boosters practically never fail, when they do, the result is usually a massive vacuum leak from a breached diaphragm.
Check valves can go too (also very rare), but there are simple tests to rule both of these out (see Brenthlehr's post above)

After having been sitting for a year, I would be more inclined to do a full brake service then bleed the brakes again (don't forget about the 5th bleeder screw).
Nothing like seized callipers/sliders to make the brakes seem ineffective.
BB

:whs:

I used to remove these on my old school street rods and put back together after they were polished/chromed, but never removed one due to failure.

[scotty]

I’ve had hard brakes that don’t do much, and I’m trying to figure it out. I replaced the master and front calipers about 6 months ago and they were working fine after bleeding a few times. Now, the peddle is very hard and they work badly. I popped off the check valve and heard a loud sucking sound, so I’m assuming the booster was holding a seal. The check valve tested good. The peddle stays the same when you run the engine and turn it off. It doesn’t climb or sink. It stays the same when you pump the peddle with it off or running, and doesn’t change when you start the van with the peddle depressed. Is that a bad booster? I got sidetracked thinking that it was a vacuum problem after I tested the vacuum at the hose into the booster and it was 5 Hgv. Not sure if that’s what it’s supposed to be, but I was told it should be closer to 20. I smoke tested the manifold and found some leaks on the valve cover gasket and at the hose from the PCV valve and the EGR modulator. I changed all that stuff, and it still measures 5 wherever I test it on the manifold, with the air box snorkel blocked -off. I’m starting to think that I’m just going to try and change the brake booster and see what happens.

[scotty]

Snorkel was only blocked off when I was putting smoke into the manifold.

[Burntboot]

"I replaced the master and front calipers about 6 months ago and they were working fine after bleeding a few times. Now, the peddle is very hard and they work badly."

Are you saying the problem was resolved with the parts that were replaced but the fault has now returned?

[scotty]

The problem started after I replaced the master and wheel
cylinders, but I don’t think they are related.

[Burntboot]

Boosters are not a known problem area and I wouldn't go changing one unless I was damn sure mine was faulty (horrid job to do)

Generally speaking, when a problem develops shortly after installing new parts, its always best to revisit last work performed, before jumping to new repairs.
Were the parts new or remanufactured?
When you were bleeding did you get clear fluid from all 5 bleeder screws?

So its clear you replaced the master, but was it fr callipers or rear wheel cylinders that was replaced at same time?
Why were those parts replaced? (leaks, maintenance, parts cannon??)

A hard pedal can be caused by several different things.
My money would be on seized front brakes (pads welded to saddle &/or sliders seized)
At the very least, I would want to eliminate everything I could before succumbing to a Booster replacement

[scotty]

I replaced the front calipers and master with new parts. I drove it for 6 months after the work. I needed to bleed it a couple of times to get them to work well. I checked the back brake cylinders for leaks and bleed them too. The rear brake arm to work ok when I just use the handbrake to stop the van. The rear shoes still had a lot of material, so I just bleed the lines and didn’t change anything on the back. I could replace the rear cylinders just to see if it makes any difference, I have a set on the shelf. But, I can’t really get past the fact that I’m only getting 1/4 of the vacuum that should be created from the manifold. Unless 5 Hgv is normal? Someone told me the car would barely run with that low a measurement, but it runs fine. I have tried a couple of different vacuum gauges with no change. I have also been told that the current amount of vacuum is enough to get
the brakes to work correctly.

I have only been able to find a new brake booster for the 84’ van. anyone know a source for one or if the 84’ will work on an 87’?

[timsrv]

Is it possible you got grease or brake fluid on the friction surfaces? Brakes rely on friction and grease/brake fluid contamination will destroy their ability to do their job. Rotors and drums can also become "glazed" and that can also have similar effects. If there is contamination, you will need to replace the shoes/pads and it's highly recommended the rotors/drums be turned or replaced. Tim

[scotty]

I don’t think so. I was pretty deliberate and clean when I did the work. I used a pneumatic brake bleeder and sprayed everything down afterward. They were working fine for about 5000 miles.

I built a little smoke machine and found a few leaks. There was a big one on the valve cover gasket, but fixing them made no change in the vacuum measurement or the performance of the brakes. I’m leaning towards replacing the booster now. It looks like a real pain in the ass, but an easier job than replacing the intake gasket with the engine in the van.

[Burntboot]

Even if the rear wheel cylinders were seized it wouldn't create your current issue.
I haven't used a vacuum gauge in years so can't advise there but there are ways to assess the integrity of the motor.

If the engine isn't producing sufficient vacuum to supply the booster, replacing the booster isnt going to solve that.

Either theres a blockage in the line between the engine and the booster or the engine has a problem.
You're going to have to work your way thru things.
Part of proper diagnostic procedures is as much ruling things out, as it is about finding whats at fault

Disconnecting the hose to the booster should cause the engine to stall at idle(massive vacuum leak)
If it doesn't, work your way back towards the engine till it does.
Knowing compression and leak-down numbers may also shed some light as would any stored codes.
Verifying timing is accurate and the balancer is intact would also be on my list.

It's still worth revisiting the front callipers, just to make sure the pads and sliders are free
Up here, servicing every 6 months is standard fare.

The more variables you can eliminate from the equation, the better

[timsrv]

To my knowledge, about the only thing that can go wrong with a vacuum booster is a busted diaphragm. You can test the diaphragm by putting vacuum to it, then seeing if it holds. If you don't have a mityvac or similar, you could put a hose on it, suck with your mouth, put your tongue over the hose (to trap vacuum). If you can't achieve a vacuum, then the diaphragm is broke. If you can achieve vacuum, and it stays there for a few seconds, then the diaphragm is good. Tim

[scotty]

I couldn’t find any more vac leaks with the smoker, so I went and rented a vac pump from autozone. I hooked it up to the booster and drove the van with an extension cord hanging out the window and only had to move the van about 10 feet to discover that the booster was working fine. My problem is low vacuum. I did the test with the vacuum gauge to check for a clogged exhaust. I revved it up and looked for a dropping vac level, but it came back to the starting point and didn’t move when it was revived up to 3k rpm. I pulled the o2 sensor out and tested with it out, and that didn’t change anything. I can’t really wrap my head around what could cause it to lose so much vacuum and yet be so hard to detect.

[VanCo]

Low vacuum, check for - Vacuum leaks (I see you've checked this), blocked exhaust (I see you've checked this too), low compression, excessive cylinder leak down, ignition timing off (verify TDC on balancer), timing chain stretch, timing chain skipped tooth.

When you're having trouble diagnosing something it's important to not assume anything. Test it all even if you feel it's unlikely.

[scotty]

I did a compression check cold and I got between 160
-170lbs on all cylinders. I’ll check the timing just to see,
but It runs fine, which I’ve been told is nearly impossible with the low vacuum pressure I’m getting. I’m starting to think I should just get an auxiliary vacuum pump and hook it directly to the booster and call it a day.

[timsrv]

I'm thinking it's gotta be a clog in a vacuum port or maybe a vacuum hose that's collapsing inside. There's also a check valve that helps the booster retain vacuum during times when engine vacuum is low. If the engine vacuum was that low it would run like total crap. Tim

[scotty]

I checked the valve at the booster, and it seems to be holding fine when I manually checked it. Is there another valve in the system? I’ll check the ports and lines. Thanks

[VanCo]

Have you checked vacuum at multiple different ports? PCV etc.

[timsrv]

I checked the valve at the booster, and it seems to be holding fine when I manually checked it. Is there another valve in the system? I’ll check the ports and lines. Thanks

Just the valve at the inlet of the booster. Vacuum is required for NA engines to idle, so if yours runs reasonably well, I would suspect a clog or maybe a leak somewhere in the booster supply. If you haven't already done it, follow that line all the way back from the booster to the manifold to insure there's no physical damage to it. You can also plug it on one end, then use a Mitivac or even your mouth to create a vacuum in it. If it leaks, you will be able to tell. Sometimes rubber hoses get soft and will collapse when a vacuum is applied. I've also seen them separate inside and collapse an inner layer while still looking good on the outside. Tim

[scotty]

I found the leak. Way up in the front near the bumper where the booster vacuum line exits the interior through the body it joins another long vacuum line that also comes from the engine area. They meet at a small plastic T connector that had broken.

[timsrv]

I found the leak. Way up in the front near the bumper where the booster vacuum line exits the interior through the body it joins another long vacuum line that also comes from the engine area. They meet at a small plastic T connector that had broken.

:dance2::clap: