have a 86 E350 motor home that has had constant brake problems since I got it. First problem was the right front (disc brake)would lock up. This happened on two trips. The first time I replace the rubber hoses at both front wheels. Took it on the second trip it did it again. replaced the master cylinder and replaced pads on the front, and this appears to have cured that problem. Now My brakes in general don't seem to work as good as they should. I tried to pull the rear drums off but found I didn;'t have the tools to do this. Does anyone know what size the big nut is inside the housing? Is there a brake proportioning valve in the line anywhere that could be limiting fluid to the rear shoes? I think the front disc brakes are working ok, I believe the problem is in the rear. This vehicle has sat most of its 18 years as it only has 60 thousand miles on it. Anyone have any ideas??? thanx. wnk.

 

Try bleeding the back brakes first.... THen the fronts. The front brakes do somewhere between 65% and 80% of the stopping.. IT may just have glazed rotors..

 

If you had a brake caliper hanging replace both front brake calipers. Prefill the new ones with brake fluid before installing. For your 86 they are only $34 each at Autozone.

Next, assuming the pads and discs are good on the front, I'd completely replace the fluid in the brake system. If you've never replaced the fluid it's gotta be loaded with water and probably is boiling . Suck out all of the fluid from the reservoir and then replace it with new DOT4 fluid. Starting with the farthest-most brake, (which in your case would be the right rear) bleed a cup of fluid from each rear line and maybe half a cup from the fronts. Remember to keep filling the reservoir as it goes down.

At this point I wouldn't worry about the rear drums yet as it's a beeitch getting the drums off.

 

DOT 4 i think you mean DOT 3 dot 4 would require a system upgrade and those two fluids do not mix they become corrosive and will eat all the rubber in the system

 

3 and 4 do mix as both are Polyalkalene Glycol Ethel based fluids. 5.1 can even be mixed with 3 and 4. DOT 5 should not be mixed with 3, 4 or 5.1.

DOT 4 contains borate esters in addition to what is contained in DOT 3.

You probably were thinking about 5 which will do as you say, and rather quickly. You will normally see leakage in 2-3 hours at any rubber o-rings and hoses.

Now when topping off a system I would use the same type that is in it, but when you buy a used vehicle, there's no way of knowing which it is so DOT3 and 4 are mixed all the time.

 

Thanx fellas for the advice. Yes, I mean't to tell you that is exactly what I did the last time the brakes locked up. I replaced the front pads and both calipers and the master cylinder. That is why I think the problem must be in the rear, as everything up front is new!! I will try to bleed both rear brakes. If it comes to removing the rear drums do you have any advice. I have already found out that I will need to remove the axles. Can you tell me what I will need for tools? I have never removed rear drums on anything like this, only on passenger cars. thanx. again. wnk.

 

These vehicles have a 5 digit odometer. Could have 160,000 miles or more. Might want to have it checked. Found out my '86 had 190,000 miles (or more) and not 90,000 miles when I bought it. Spent a bunch to upgrade the engine, then trashed it due to it being too worn to handle mods.
Munrow

 

Normally the E-350 rv's have the lower mileage because they sit so much. Carfax can tell for sure but it will cost $20. Mine only has 40k on it.

I haven't tried very hard to get the rear drums off after reading my Haynes and it saying that I may have to pull the axles. I'm not willing to go that far.

I really have a hard time believing that your rear brakes are causing the problems though. Usually they say that when the rear brakes are gone, the front end will really dive when braking hard. I think that the fronts do 85% of the braking on the E-350 cutaways. Maybe it is something with the proportioning valve but it would be doing the opposite of what you're thinking. It would not be giving the front brakes enough fluid. While the rear brakes do help somewhat, really they are mainly there to help keep the vehicle level on stops. If you've ever tried to stop a vehicle with the rear brakes only you'll see that they don't do a lot for stopping.

Again, because you didn't mention complete fluid replacement, that can really make a difference if it hasn't been done. Brake fluid is a natural sponge for water. Most 'experts' say to change it every 12k miles or 1 year. I doubt that many people follow that advice however. I know I don't. The RV was the first vehicle I ever replaced the brake fluid in.

This may be a job for a brake specialist if you really feel that there is a brake problem. What is it that makes you think there is a problem? Is your pedal going clear to the floor? Tie everything down in the RV and go out alone and see if you can lock them up. That will sure give you a good idea as to how they are working. Have someone watch from the outside and see what happens to the tires when you do it.