I am sorry for all the questions right now. I've got this van in my possession to take a holiday in but it's got some nagging issues. This is a 1991 B250 Roadtrek conversion and I can't bleed the brakes for the life of me. The more I bleed them the more air I get!

I think it is the master or the proportioning valve that is letting air into the system when bleeding the brakes. There are no fluid leaks so I think this is a vacuum issue when the master is sucking up new fluid.


Would anybody happen to have any pointers on how to deal with this? I am not sure if the fronts being harder to bleed than the rears is normal or not and I don't know how to check the master vs. the proportional valve.


Thank you, Steve

 

How are you trying to bleed them?

 

The old fashioned way, the wife pumps and I let the fluid out.

Seriously, I started at the drivers rear because it was the longest one from the master by way of piping. On the wheel end I put a clear tube on the bleeder nipple into a glass jar sitting on the leaf spring. I have the wife push on the pedal, I open the bleeder and let the fluid out, close the bleeder, and get her to let out the pedal. At first my process is to pump the master dry and then fill it up with new fluid. From then on I just keep pouring in more fluid until I am happy with the colour coming out and lack of air.

She's helped me flush my 1992 VW Golf and 2004 Dodge 1500 so I can't see it being a problem with what we are doing. At first I figured it was but I can hear all the air moving around in the tubing before it even gets to the calipers.

Steve

 

Sorry to say but that is a terrible idea. You are much better off running the MC low but not dry. Then add a bit of fluid and pump a bit more out. Running the MC dry introduces air into the brake system which includes the proportioning and ABS valves. These valves can get air bound and give you a world of grief trying to get the air out of them.

In all my years I've never heard air moving inside of a brake line. Could you clarify this a bit?

 

Pretty difficult to get the air out of the MC when you let it go dry.

Perhaps a bench bleeding then re install

 

Best way to bleed the brakes on these van is:
1) Open the bleeder valve.
2) Have your helper push the pedal to the floor and hold it there.
3) Close the bleeder valve.
4) Have your helper release the brake pedal.
5) Repeat steps 1-4 till all the air is out of each bleeder.

 

Well, I was able to get the air out using a vacuum bleeder. I'm not sure what exactly the problem was but perhaps it was the way I let the fluid run down. I also figured out that the front passenger brake hose is collapsed and slowing the flow of fluid to the caliper and making the van swerve...or that is my theory anyway. I'll try to get a chance to change those front lines while I'm out on the road...I'm going for 2 weeks so talk to you later.
Cheers, Steve

 

collapsed front rubber brake lines are a common problem... replace both sides

 

I just got back from a 6000 km ride down the centre of the US and back and I was able to pick up a right hose but will have to find a left locally. It will be nice to get rid of the hit the brakes and start steering all over the place issue... I am impressed that this thing can hold its own on the interstates despite being so old. I saw dozens of much newer vehicles dead on the road on down South.
Steve

 

when you get that left hose... (try www.rockauto.com ) try replacing all the fluid in the brake lines with new fluid... brake fluid attracts water as it ages and will rust lines and brake fittings... use that vacuum pump to pull new fluid through the lines...

glad for you that you were able to run a long trip with no serious problems on the way...