99% sure it's the booster. Thoughts?

[Brian VT]

I bought one once. It was like eggshell. It broke to pieces in no time. Never again.

Hmmm. I've had my Mityvac (the cheap plastic one) for many years and lots of use. And now I keep it with my IDI in case I run out of fuel. Then I can attach it to the Shrader valve at the fuel filter (after removing the valve core) and prime fuel the system.

 

[Cubey]

Hmmm. I've had my Mityvac (the cheap plastic one) for many years and lots of use. And now I keep it with my IDI in case I run out of fuel. Then I can attach it to the Shrader valve at the fuel filter (after removing the valve core) and prime fuel the system.

Yeah dunno, the one I had was total junk.

I just went on AliExpress and ordered these, and a few other tool items. $14.58 with tax and free shipping for everything.

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Those same blue bleeder valve connectors are $8 on crapazon, and the in line check valve for bleeding is $10; after being imported from China marked up by resellers.

I'm not in a hurry, I can wait 2-3 weeks for them to come directly rom China. It cuts out two middleman: resellers on Amazon, and Amazon itself. I'd have probably spent $60-70 buying from Amazon for the same exact items.

 

[franklin2]

I've never understood "bench" bleeding. "Do a task, but the hardest way possible!". Just mount it on the booster and "bench" bleed it there with the pedal. I do still have an old bench bleed tool kit, with the little plastic fittings.

I didn't even "bench" bleed the one on the 64 Bug at all because lots of people say there's no point. And it works fine.

Perhaps I could get someone to help out here.

I've had good luck with Gator/Powerade bottle with the cap drilled twice (1 for hose, 1 for breather) for a 1 person brake bleeder. Getting a hose to stay on has always been the issue.

What if, when you install the master cylinder, that mechanically from the pedal in the car or truck, the piston in the master cylinder doesn't travel full stroke? Most don't. When you bench bleed, you are pushing the plunger in by hand till it bottoms out. This guarantees the master cylinder piston travels the full stroke and gets all of the air out.

And if you do not bench bleed in this case, you are pumping all the air in the new master cylinder into the brake system. If you did not want to flush the system out, just install the master/booster, bleed it a little bit and go, you have to bench bleed.

If you do want to flush the system, you still can, but instead of fighting all the air you will be introducing, push new fluid through from a already bled master cylinder, not all that air.

 

[Cubey]

What if, when you install the master cylinder, that mechanically from the pedal in the car or truck, the piston in the master cylinder doesn't travel full stroke? Most don't. When you bench bleed, you are pushing the plunger in by hand till it bottoms out. This guarantees the master cylinder piston travels the full stroke and gets all of the air out.

And if you do not bench bleed in this case, you are pumping all the air in the new master cylinder into the brake system. If you did not want to flush the system out, just install the master/booster, bleed it a little bit and go, you have to bench bleed.

If you do want to flush the system, you still can, but instead of fighting all the air you will be introducing, push new fluid through from a already bled master cylinder, not all that air.

I just realized, I didn't do the RV's master cylinder myself. The crappy shop in Oklahoma did, because the system was full of ATF from some idiot before I bought it, and that's the one fluid I didn't check. Old metal reservoir and metal cap, so you couldn't see it externally. Maybe I'm thinking of the F250's being bench bled in the truck.

I don't have a workbench and vise to stick it in, so it's difficult to bench bleed "properly".

I want to give the system a flush with fresh fluid, since who knows how old it is currently. I'll get a couple of quarts of DOT3 from Walmart next time I go to town, in 10-12 days from now. That should be enough to do the entire system. I have a smaller 16oz unopened bottle I got a few months ago for extra. I'll get a bottle of Gatorade for the bleed bottle too.

 

[franklin2]

It's very difficult to bleed the brakes by yourself sometimes. The problem with the mitey-vac method is the same problem you can run into with the bottle and hose method. The threads around the bleeder tend to leak air when you loosen the bleeder to bleed. It can be hit or miss. If you find you just keep getting bubbles as you continually bleed and can't seem to get it to clear up, it's usually caused by air getting around the threads on the bleeder screw.

 

[Cubey]

It's very difficult to bleed the brakes by yourself sometimes. The problem with the mitey-vac method is the same problem you can run into with the bottle and hose method. The threads around the bleeder tend to leak air when you loosen the bleeder to bleed. It can be hit or miss. If you find you just keep getting bubbles as you continually bleed and can't seem to get it to clear up, it's usually caused by air getting around the threads on the bleeder screw.

If you're careful about applying it, teflon tape can help to seal the threads. The speed bleeders have something on the threads to help seal. Sadly, you can only get the rear ones for this van now. The longer ones for the front aren't being made anymore.

 

[IDIBRONCO]

I don't have a workbench and vise to stick it in, so it's difficult to bench bleed "properly".

Not necessarily. I have a rubber tipped syringe that's made for bleeding master cylinders. I just full each reservoir and then use the syringe to push that fluid backward through the fittings for the lines until air no longer comes out. It's backward bleeding that's, easy and doesn't require a vise or a helper. As long as you're careful to get all of the air out of the syringe before you use it, it doesn't take very long either. I love this since I've had mixed results with bench bleeding the traditional way in the past. There's one listed on Amazon for $16.99. I used "brake bench bleeder" as the search. It comes with a hose and a few more rubber pieces. The pictures show that you can use it for brake bleeding at the calipers and rotors. It might work for that, it might not.

 

[franklin2]

I don't have a workbench and vise to stick it in, so it's difficult to bench bleed "properly".

Since you live on the road most of the time, and do a lot of your own work, it may be worthwhile to change this situation. A vise can be expensive new, but maybe you can pick a used one up in a sale. Didn't you have a trailer you pull? Somewhere on the tongue of the trailer would be a good place to mount a vise, either temp or permanently.

 

[franklin2]

And by the way on different bench bleeding methods, they started to give you block off plugs for the master instead of the fittings and the little rubber hoses. I am not sure how it works, but I really like the plug-off method. You know you have all the air out when you push on the master cylinder piston and it will not budge. Using the plug method, I have had to pump a master cylinder over 30 times to get every little bit of movement out of the piston.

 

[IDIBRONCO]

Since you live on the road most of the time, and do a lot of your own work, it may be worthwhile to change this situation. A vise can be expensive new, but maybe you can pick a used one up in a sale. Didn't you have a trailer you pull? Somewhere on the tongue of the trailer would be a good place to mount a vise, either temp or permanently.

Or he can have something built to slide into a rear or front mounted receiver hitch. Just throwing that out there.

 

[Cubey]

Hm, maybe I'm partly mistaken. I honestly thought it didn't have much travel without vac based on feeling.

It does have a lot pedal travel when off for a couple days, so no vacuum. I didn't press the pedal any today until I started recording.

It goes to the floor with vacuum.

Could be the master cylinder. But it may have taken out the booster too. I guess I'll start with the master cylinder and if that solves it, I might just return the booster I ordered.

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Or he can have something built to slide into a rear or front mounted receiver hitch. Just throwing that out there.

You can buy winch mounts for about $20 that go in 2" receivers. I have thought about that.

Since you live on the road most of the time, and do a lot of your own work, it may be worthwhile to change this situation. A vise can be expensive new, but maybe you can pick a used one up in a sale. Didn't you have a trailer you pull? Somewhere on the tongue of the trailer would be a good place to mount a vise, either temp or permanently.

I have a little table clamp on one, but I left it in Arkansas, a couple months ago. I quit pulling the trailer full time a couple years ago when I got the VW bug. Although, the bug is in Arkansas right now, because I'm pulling the trailer back to Arkansas around March/April.. It's been summer stored out here by Yuma because I bought the bug when I shouldn't have, meaning I had two things to tow, but can only tow one at a time.

A vise is kinda big and heavy for such occasional use. When I was in the RV, space wasn't as much of a problem, compared to this van. I carry a lot of other tools full time though.

 

[Cubey]

It's very hard to see without looking for it. The booster looks pretty corroded below the master cylinder.

So, I think it's safe to say it needs both the MC and booster.

If it also needs calipers/cylinders, that'll have to wait until I get back to Arkansas and have the driveway to work in again.

But hopefully those two, plus all fresh fluid, fixes the problem. I'll probably try gravity bleeding because that can work well with minimal effort. I'll just have to set alarms/timers on my phone to remind me to check it every so often.

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[IDIBRONCO]

It's also damp around the master cylinder. That's a sure sign that the rear seal on the master cylinder is at least weeping.

 

[Cubey]

It's also damp around the master cylinder. That's a sure sign that the rear seal on the master cylinder is at least weeping.

Yeah. It's pretty dark and hidden, so at first look, it appears ok. Had to get the phone down in there with the flash on.

 

[Cubey]

Yep, it's leaking.

I only got as far as getting the MC off today. I wrapped paper towels over the lines to keep out dust. (windy, dusty, desert environment)

The moisture in the booster is brake fluid. The moisture outside is spray lubricant from soaking the booster threads.

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