Humbled by brake bleeding - FIXED

[heliodon]

I worked on bleeding my brakes today. It did not go well and I could use some advice.

I acquired my 1990 Westfalia with 90K miles on its 2.1L WBX and manual transmission a little over a year ago. In December my clutch slave started leaking. After replacing both clutch slave and clutch master I thought I would reward myself with a Motive Pressure Bleeder. It worked like a champ bleeding the clutch and the clutch system has performed well in 1,500 miles of travel since December.

While my brakes have been working fine I had no idea how old my brake fluid was. Mindful of recommendations to change the brake fluid every two years I decided to flush the braking system with new fluid. I did my Samba homework by reading brake-related threads and set about the flush this morning. Working from the rear passenger side wheel forward I removed each wheel, gave the flex hoses a good inspection, and bled the brakes using the Motive bleeder. The bleeder was pressurized to 10 psi and I used clear plastic tubing at the bleeding valves to direct fluid into a clear bottle. Tubing on, open bleeding valve ¾ turn, drain a half pint of fluid, close bleeder, remove hose. The latter half of the flush at each wheel was clean brake fluid. Happily all of the bleeding valves loosened easily. The only wrinkle occurred at the last wheel (front driver’s side) where the brake fluid did not flow when the bleeder was opened or even removed. I gave the brake pedal a push to see if that would clear it out and it started to flow. For the other cylinders there was no push of the brake petal.

After finishing the four wheels I checked the brakes and found a soft pedal that would push to the floor. Drat. Starting the engine and the power boost caused the pedal to go very soft. I decided to bleed the brakes again (this time without removing the wheels). For the first bleed the parking brake was on; I released it for the second. During the second bleed the brake fluid coming out of the bleeders was clean and I saw only a couple of pinhead-sized bubbles. After bleeding was completed I still had the soft pedal, just as before. Becoming mildly desperate I decided that perhaps I had not bled enough so, after a run to pick up a couple more quarts of DOT4 brake fluid, I bled a third time. This round collected three quarters of a pint from each wheel. By now I had run three quarts of brake fluid through the system. Again the brake fluid emerged clean and again the brake pedal was soft.

I am pretty new to this but it seems to me that the system is bleeding fine. I cannot find leaks anywhere in the braking circuits (although I will look again carefully tomorrow). The brake master cylinder was working fine when I started but I am wondering now if I somehow pooched it. Revisiting the various brake hydraulics posts on Samba (I would be lost without this site) I find reference to master cylinder seals being harmed by piston travel beyond normal range during bleeding. Perhaps that is my problem. I did press the petal that far when checking to see if the brakes worked after bleeding.

I am feeling a pint short of handy this evening. In my shoes what would you do next?
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Cheers,
Cris
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90 Westfalia (current)
91 Cabriolet (current)
60 Bugeye Sprite (good prep for VWs)

[bjrogers86auto]

After my brake job last spring I attempted bleeding with my buddy in the van and me bleeding. I did it at least 4 times without success.

I ended up driving carefully to my mechanic who finished the job with me at the pedal. It takes a long time to get it done!

Good luck,
Brian.
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86 Vanagon GL Westfalia 2.1
18 Nissan Frontier Pro 4X
19 Honda Civic Hatchback

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[levi]

When all else fails you can always try back-bleeding.
Run a search on that here and you'll get the particulars.
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[houndsbourgh]

Vanagons are very sensitive to any agitation of the fluid during the bleed. Best way to bleed is a pressure bleeder. There are a few posts about building you own. Mine was the $5.00 Ace lawn sprayer, tubing, zip ties, brass barbett fiting and a spare cap. Even the act of adding fluid without waiting for the air to dissapte can mess it up. Thats a good 5-10 min wait after you pour it in. Disconnecting the vacume line on the booster during the bleed helps alot also. Its all in the Bentley. Good luck.
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1984 1.9L Westfalia added a peloquin diff + a little lift and a lot of TLC
Retrotec Classic 29er
Salsa Elmar 29er single speed
Surly 1x8 internal hub (Bad weather transportation)
My lovely wife is not crazy and drives in the winter.

[morymob]

Easier, to me is, suck old fluid from mstr cyl(keep it full at all times). Start at rr, bleed until clear and at this time get this wheel/brake correct(pedal hard) before going to next wheel, u will know where a problem is as u go and can correct.

[Team WorldTour]

In the shop, we use an old water bottle and a hose for bleeding. Works like a charm!
Take a clear bottle (of any sort!), and pour an inch or two of brake fluid in.
Insert 6mm hose.
Connect the other end of the hose to bleeder valve on brakes.
Put bottle where you can see it, and fill brake reservoir.
Pump brakes until no more bubbles come out.
Close bleeder valve, top up reservoir, and move on to the next wheel.

Fast, cheap and effective.
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[RadioRental]

it sounds like you're thorough and did the job properly. That stuck drivers side front is a puzzle. It could very well be that you have a faulty master now. Im no expert on brakes but i think even with air in the system you get a more spongy feel, not the complete lack of pressure you're experiencing. Do you have any stopping power at all? Jack a front wheel up, wedge something down on to the pedal, if a seal has gone I would imagine that after a few minutes the pressure would have equalised and you might be able to rotate the wheel by hand.
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'87 2.1. 125K 4spd Not rebuilt "Red Dwarf"

[Fishguy]

It's a 2 man job. One @ the pedal & one at the wheel. Tubing on the bleeder nipple draining into a clear plastic pop bottle. Open the bleeder valve & have assistant gently push the brake pedal to the floor & hold it there while you close the bleeder valve. Have assistant gently release the brake pedal. Open bleeder valve & have assistant gently push the brake pedal to the floor........ Continue to repeat this process until you have clear fluid with no foaming bubbles in the bottle. The guy at the wheel controls the process by telling the assistant when to press & when to release depending on wether the valve is open or closed. NEVER release the pedal when the valve is open, even if you have the end of the tube immersed in the old fluid in the bottle, air can leak back into the system through the threads on the bleeder valve.
I have never have this method fail to work on the first attemp...... even with the hydraulic clutch system.

[Terry Kay]

Do this & it's a one man job---no mechanical or pressurized bleeding required.

Start at the right hand rear wheel.
Make sure the master cylinder is full.
Open up the bleeder & let it run--watch for air bubbles.
Take your time--let it run, and take a trip back the master cylinder to make sure it stays full.
Close up the right hand bleeder.
Do the same with the left hand rear wheel, the right hand front & left hand front.

The manual pumping of the pedal is the best way to get this done-but if your short an extra leg, the gravity bleed works well.
What might be fighting you here with the power bleeder is the proportioning valve.
It might be o the way out preventing you from getting the back end bled.
Happens all the time---

Do the gravity bleed --it's simple and it's a one man operation--just don't let the master cylinder go dry while it's bleeding.
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T.K.

[heliodon]

Thanks for the suggestion TK. I can find a second pair of legs and try a normal bleed next, or do you think the gravity bleed would be better?.

When you mention the possible influence of the proportioning valve I am trying to visualize how this would work. During the third bleed with the Motive I collected 3/4 of a pint of clean brake fluid from each of the rear cylinders - no bubbles. It took between 5 and 10 minutes at each cylinder. Would the brake fluid have bypassed a large air bubble somewhere? FWIW, the van was level during the bleeding.
_________________
Cheers,
Cris
_________________
90 Westfalia (current)
91 Cabriolet (current)
60 Bugeye Sprite (good prep for VWs)

[dubbified]

I have had a motive power bleeder for years. We used to use power bleeders in our shop, our teacher built several for doing other systems, coolant and other oils, that system was backed up by an air compressor and adjustable regulator.

Is the fluid you are pushing thruogh the system, the same volume as you're capturing when bleeding??

Parking brake on is your issue, hands down.

Bleeding with a power motive is the easiest thing, and produces results vs the headaches I'm seeing in this thread.

There is no concern about a person on the pedal, no pedal action is required at all.

I fill up the motive power bleeder 2/3 with fluid, I pre turn the hose radially, attach the cup/lid to the booster, and my resulting connection is a kink free hose..

Then I pump to 15-18psi.. and let the motive sit.

I started rear right, front left, front right, rear left. Then I went in other patterns front to back... until no air was seen..

While I'm checking fluid frequently, and on each corner, while each valve is open I go back to the pedal, I give the pedal a full cycle, even while the motive is under pressure.. then close the bleeder, and move to the next corner..

I have to say it was a snap, 0 difficulty.. wait getting down under the van was the difficulty.

If you are not getting fluid when the system is under pressure, you most likely have rusted calipers, or bleeder valves.

[heliodon]

Here is a final post to bring closure to this thread. It turns out that the brake master cylinder had failed. I have replaced it, adjusted my rear shoes, bled the system yet again and all is well.

Thank you to all who offered suggestions. I have now experienced bleeding the brakes with the normal two-person procedure, using gravity alone, and with the Motive pressure bleeder. Each method seems to work fine. The one tip I can offer was the discovery that using my little LED headlamp as a backlight for the clear tube attached to a bleeder revealed useful detail about the flow of brake fluid and the presence of tiny bubbles.

Again, thank you for the advice.
_________________
Cheers,
Cris
_________________
90 Westfalia (current)
91 Cabriolet (current)
60 Bugeye Sprite (good prep for VWs)

[mrcool]

Dang, I am having the same issue. Guess I should look into replacing the brake master cylinder... The RR drained about 200mL then stopped... now it won't drain with gravity or pressure bleeding.

Thanks for updating the thread with your solution!!!!

[geodude]

Before you jump to changing the master inspect your brakes carefully. I've bleed many a Vanagon brake (and other cars) and it was never very hard except one time. One of the front calipers was slightly (and I do mean slightly) off so the pad was meeting the disk at a slight angle. That slight angle and the caliper compressing enough to take it up made the brakes very spongy. Shine a light up past the pads and ensure they are all nice and parallel to the disk.
Plus the other things people have mentioned. Adjusted back brakes, parking brake off during bleeding, etc.
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1988 GL Camper
1991 Multivan — the basket case

[mrcool]

^good point.

I just came back to post that the issue most likely stemmed from the fact that I had to replace my master clutch cylinder because the back nipple broke. Most likely introduced tons of air to the system.

I was using a mityvac hand pump and it was pretty much useless trying to get all the air out and i kept losing vacuum even with grease. The rubber nozzle it came with to attach to the bleeder valve was pretty lose. I bought the harbor freight pneumatic pressure bleeder and it saved me hours of pumping. The rubber nozzle was infinitely better than the mityvac one. I'm shocked HF had a better product.

OH also the auto top off brake fluid bottle it came with made my life so much easier!