I have an 84 e340 rv that I bought as a project. I've got it running good now but I need it to stop. I drove it home when I purchased it about 100 miles. The brakes worked fine until right before I got home and they started to get spongy and had to pump them. Now pumping doesn't help. You have to put the pedal to the floor to stop. I checked the master cylinder and the fluid looks very old and it was very low in the rear reservor. Put some fluid in looked at all the lines and fittings all the way to all the wheels. Nothing noticeable. Is this a bad master cylinder, brake booster, leak or something else. I just want to know where you would start if it were you or has anyone had this problem and know what it is?

 

I would start by flushing all the lines to the wheel cylinders/ calipers...get some fresh brake fluid in there and get them bled real good. See how they are at that point.

Do a good check of the entire system while bleeding them and check for leaks.

That's where I'd start

What type RV is this? Sounds like a class C? All Ford? What motor, not that it really matters.

 

Did the RV sit for awhile before you bought it?

Wheel cylinders may have blown their seals because of sitting up, rusting in place, and when you drove it home they failed. I guess it's a lot harder to do than a pickup or Bronco type truck, but you should pull the wheels and check the pads/shoes also.

Let us know what you find, ok?

 

Personally, I would pull the rear drums and have a good look, clean and replace parts as necessary. Then move to the front calipers, clean and replace parts as necessary. Then do a complete flush and refill. You will more than likely have plenty of old, nasty fluid in there that will need to be flushed out and replaced with clean, new, fresh fluid. Brake fluid has a tendency to absorb moisture from the air, or anywhere else that it can get it. After it has been sitting up a while, the moisture that it absorbs can start causing rust on some components inside the system (such as wheel cylinders). I would also check the thickness of the rotors and drums while I was in there inspecting everything else. Chances are you will find your problem there.

 

Class C's use the E350 (Econoline) "Cut-Away" body. Ford cuts the cargo van body off behind the front seats.

These are sold to RV dealers to install Class C motor home bodies, also sold to U-Haul, aftermarket body makers that install box van, airport shuttle, ambulance and etc bodies.

Everyone of these I've ever seen have dual rear wheels, so pulling the rear hub 'n drums isn't any picnic, it's a tedious job.

E350's have a Dana 70 rear axle, the engine in this '84 is most likely a 460 4V, trans is a C6.