E-350 econoline cargo van brake pressure issue

Ask our auto mechanics for help to all your Ford truck questions now.
ktn2010
Posts: 2
Joined: Mon Apr 29, 2013 8:14 am

E-350 econoline cargo van brake pressure issue

Unread post by ktn2010 » Mon Apr 29, 2013 8:23 am

I have a 2007 E-350 econoline cargo van that had brake failure and has not lost any fluid. The brake was depressed and went to the floor and stayed in place causing me to depress the emergency brake to slow to a stop. I pulled the pedal and it went back to normal position. The brake pedal now goes to the floor and returns but no pressure and fluid is normal full. I have been told by several mechanics they are not familiar with this symptom and are perplexed ? What should I look for or at to resolve this issue ?

User avatar
carriedi
Posts: 2573
Joined: Wed Apr 10, 2013 12:42 pm

Re: E-350 econoline cargo van brake pressure issue

Unread post by carriedi » Mon Apr 29, 2013 10:23 pm

brakes work on the principal of transmission of fluid-pressure. (Pascal's law) Pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions such that the pressure ratio remains the same. So the brake master cylinder applies pressure throughout the system. If you have a loss of pressure without a loss of fluid then your master isn't applying the pressure. That would mean that you have a bad master cylinder. Here's the odd thing. Masters usually go out by losing pressure and going to the floor once but acting normal after a quick pump. Usually a seal bypassing but then resealing. Dirt, rust in the bottom of the master can cause this. Once the master has gone to the floor it should be recommended to have it replaced. Because the master normally only travels in a small section of the travel. debris builds up in the area that the plunger doesn't wipe. So if the plunger goes all the way down it will usually be damaged and carry back some of that debris.

To have you brake pedal stick all the way to the floor with no braking, meaning that both parts of the fluid compartments failed, I would look at the fluid to see if it has been contaminated. If there has been something other than dot spec. brake fluid added to the system you may have more problems that just your master cylinder. Any type of hydraulic fluid such as power steering fluid, motor oil etc. (petroleum product) will damage any rubberized components in the braking system. Master, hoses, wheel cylinders, calipers, combination valves and ABS components. So, check the fluid. Also, brake fluid will take the paint off you car. Don't let it come into contact with your paint. If you put your clean finger into the brake fluid in the master's reservoir and rub your wet finger and thumb together (away from the vehicle so you don't drip on the van) as you rub them together the brake fluid will feel like it is cleaning your fingers and taking the oil off your skin. it will seem to get squeaky clean. That's what brake fluid feels like. If the fluid feels oily, slippery, and stays that way as you rub your fingers together, it is most likely contaminated. You will need to remove any affected components and flush out the entire system.

If you shut off the engine off and pump the vacuum pressure out of the booster, doe it change how far down the pedal will go down or does it still go down to the floor. (pump about 8 times as far as it will go down)

let me know what you find out.
Browse "SIMILAR TOPICS" At The Bottom Of This Page.

ktn2010
Posts: 2
Joined: Mon Apr 29, 2013 8:14 am

Re: E-350 econoline cargo van brake pressure issue

Unread post by ktn2010 » Tue Apr 30, 2013 10:22 am

I did find black finings in the bottom of the fluid reservoir and cleaned/flushed out. I replaced the master cylinder and bled all lines filling with new fluid. Still had issue with pressure at pedal and was told to leave cap off reservoir over night and found that in morning I replaced cap started vehicle and had full pressure and complete operation. Not sure on the logic but it worked. Thank you for your help with the specific details it made a lot of sense.

User avatar
carriedi
Posts: 2573
Joined: Wed Apr 10, 2013 12:42 pm

Re: E-350 econoline cargo van brake pressure issue

Unread post by carriedi » Thu May 02, 2013 12:07 pm

leaving the top off is not a good idea because brake fluid is hygroscopic. (absorbs water form the atmosphere) so be careful. Air in the brake lines close to the master will travel back up through the line to the reservoir even with the cap on
Browse "SIMILAR TOPICS" At The Bottom Of This Page.

  • Similar Topics
    Replies
    Views
    Last post