Ford van rear abs problem

[svoman2300]

This is long
I have a 93 Ford E350 7.3 diesel . For the last year the rear abs has been giving me alot of trouble.This is an intermitent problem, sometimes it'll go 2 weeks without doing it other times it 'll do it several times in one day.What is happening is when I come to a stop sometimes the rear brakes will stay on sometimes to the point where my high tourque diesel won't even budge the van.I have taken this to 4 different mechanics and have spent too much money and no one can fix it . I have replaced rear hoses,shoes,drums,master cylinder. The mechanics think I'm imagining this because they have test drove it and can't get it to do it .I finally had it happen to me where I was able to take it the last mechanic he ran his test computer and said there is no codes coming up and the only thing he could recommend is to start changing parts in the abs system starting with the cheapest and working through it till it is fixed. I'm at whits end if anybody has had a simillar problem and can help I would most appreciate it.
Rick

[helpless8528]

well i hope u fixid the problem by now , but if not check the plunger for the master cy it my be loose . it can turn in and out by vibrating and the plunger does not let the fluid release the back tires

[rhandwor]

Some of these diesels have a vacuum pump for the vacuum booster. If you changed it the rods sometimes need adjusted. I think the previous link was about manual brakes. Lay a straight edge across the front and use a ruler and measure the length. You can turn it in about 1/16 inch and try it. Don't disconnect the master cylinder try to just move it forward enough.
I have had a bad distribution valve in the brake line towards the back this splits up the fluid between front and back brakes.
How tight are the back shoes adjusted this can make a difference.
You can pull the fuse for the anti lock brakes for a few days if this solves the problem at least you isolated the problem. They sell rebuilt units on the web do a google search if you need a unit. They also offer techinical support which you can call.
If you have a vacuum pump make sure it is working.