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Ron03Allegro · 06-10-2024, 07:23 PM

I am now on the service the brake fluid. Likely is has the original 21 year old with 25k miles brake fluid, I would like to flush the fluid and fill with new.

Tomorrow I jack the rv up and go seriously looking for the master cylinder and brake fluid reservoir. I have a plumbing camera that can get most anywhere if I can't get a view otherwise. I have a little electric usb powered pump my plan is drain reservoir, fill reservoir, bleed through to wheels all lines, and top off reservoir asap.

FYI there isn't any drips the that are hitting the ground but I do see what may be brake fluid mixed with dust. I don't know if prior filling also spilled brake fluid or the master cylinder is leaking. The oily dust is on the reservior for the hydralic jack fluid. From what I read-youtune replacing the master cyclinder seems very difficult because of the access.

I have a mechanical, welder, hot rod friend, he suggests perhaps cutting and adding a access door on the drivers floor might be the way to fix the bad access problem, opinions please!

Isaac-1 · 06-10-2024, 10:49 PM

Access is not bad, it is just access and seeing the fluid level at the same time is next to impossible, this is why so many recommend the finger dip method of level checking. Note in case you did not get it the master cylinder is found inside the drivers side wheel wheel, below and just aft of the brake pedal, right behind the hydrobooster.

Mark_K5LXP · 06-11-2024, 06:07 AM

I did this last year, it sounds worse than it is. With the doghouse off you can look to the left of the engine, pretty much right underneath the brake pedal on the frame rail and see a "classic" GM style fluid reservoir (same as my '80's pickup had). If you want to contort yourself you could fill it from there but it's more readily accessed but not necessarily readily visible from the driver wheel well. I had my front wheels off so it was easy to reach in, and remove the cover. I started with removing and replacing the fluid in the reservoir, then as I went to each wheel I installed a speed bleeder and pumped the pedal. I could see the reservoir level from the top side so I could pump until I saw it was low, jump out and dump a pint in from the wheel well. Got into a "groove" where I could pump some number of times, check the speed bleeder, dump in another pint and go back to pumping. Lather, rinse, repeat for all the wheels and the job was done. Took probably 2 hours, and used right at a gallon of DOT3. If you had a helper that did nothing but pump the pedal you could go back and forth between bleeding and filling, and cut that time down a lot. No cutting of floors, no weeping or cussing.

Mark B.
Albuquerque, NM

skyryder1 · 06-11-2024, 07:08 AM

Hmm, , reading over the post, and prospects of doing a fluid replacement on my 1990 bounder. I said to myself, self, why not cut a "door" right above the master cylinder. One would have to watch out for wires and such, cut like a 4" X 4" door with hinges & slide latch, slot in carpet (which is covered by a floor mat anyway) and presto, an easy access, ,

Question, has anyone tried or seen this done?

Ron03Allegro · 06-11-2024, 01:20 PM

I finally have seen the master cylinder and the brake fluid reservoir.
To see I removed the engine cover and laid on the floor facing from the back of the engine towards the brake pedal. I can see the opaque reservoir, it has no brake fluid on the outside, I bet no one has even opened it to see or add fluid. Good news no leaking brake fluid anywhere.

People have mentioned seeing the resevoir fom behind the drivers front wheel, well their is a cut out that allows that and I could see via that using my plumbers camera but to see it will my own eyes I would need to be 2.5 foot midget I think.

The drivers floor is mostly 3/4 inch plywood above the master cylinder I will be using my camera to plot where I might cut the plywood to make a service access door. Would be great to make a access especially if it could be big enough to allow to replace master cylinder if needed. I presently would think it could be impossible to replace the master cyclinder without such a added door.

LETMGROW · 06-12-2024, 07:57 AM

Did you remove the two or three bolts which hold the shield next to the master cylinder and remove the shield?
This isn't a part you need to look at often. Why go through all the work of cutting holes in the floor and making a door when it's totally unnecessary?
I've changed the brake fluid in my coach three times in the nine years I've owned it.

skyryder1 · 06-13-2024, 05:17 AM

Quote:

Originally Posted by LETMGROW

Did you remove the two or three bolts which hold the shield next to the master cylinder and remove the shield?
This isn't a part you need to look at often. Why go through all the work of cutting holes in the floor and making a door when it's totally unnecessary?
I've changed the brake fluid in my coach three times in the nine years I've owned it.

No I haven't. I had a tough enough time seeing the shield, and thought no way. The olde body just doesn't bend like that anymore and can't see what I'm looking at he, he.
I'll take another look.

LETMGROW · 06-13-2024, 06:33 AM

Quote:

Originally Posted by skyryder1

No I haven't. I had a tough enough time seeing the shield, and thought no way. The olde body just doesn't bend like that anymore and can't see what I'm looking at he, he.
I'll take another look.

Jacking the front end of your coach up will help in accessing the cover. I use my leveling jacks and put blocks between the front cross member and the ground in case a jack might fail. Also turning the wheel in or out will add to the room you'll have to work in.

Ron03Allegro · 06-18-2024, 11:34 AM

Put 3" of wood under leveling jacks.
Turning wheel full left.
Loosen brake bleed port on driver wheel with 10mm (Metric! go figure). Just insured I could break it free to bled, of course I did not allow air in the system.

Crawled under and could touch via the "service notch" in metal the reservoir.
Cleaned reservoir area with a rag and water to eliminate getting debris in the existing brake fluid. Then removed the reservoir lid. Pushed up from edge the inner lid and stuck my finger in the fluid. Noting it seems down about 1/2 inch from the reservoir top edge. I drained old fluid into a glass jar using a little 5volt usb pump. I then measured new dot 3 fluid of the same amount into a second glass jar and pumped the clean back in. I then had my assistant (aka wife) pump and hold the brake pedal as I let brake fluid flow into a third glass jar. I pumped same about of clean fluid as bled into reservior and closed it up. I decided not to bled all the calipers a tleast for now.

LETMGROW · 06-19-2024, 08:11 AM

Ron, IMO you are only partially done with a fluid change on your coach. To do a proper brake service all the wheels should be pulled, the brake calipers removed from their mounting brackets and all contact areas between the calipers and the mounting brackets should be cleaned of any dirt and rust. You don't have to disconnect the brake hoses to accomplish this. A special brake caliper lube is available to apply to all the contact points of the caliper and the brackets. While it's apart a light sanding of the brake pads is in order too.
Once you've completed this task it's imperative the entire braking system be bled which means all four calipers to remove any and all moisture from the brake's hydraulic system. If any of this work is above your pay grade I'd highly recommend you find someone familiar with brake systems to assist you.
Even a small amount of moisture in a caliper can boil under normal braking and form an air pocket in the system resulting in your brake pedal going to the floor and having no braking whatsoever. I say this with some authority because it did happen to me. I was extremely fortunate I was able to roll to a safe stop. I was also fortunate I was just over a mile from a heavy duty truck shop. Once my brakes cooled I was able to drive slowly to the shop where they took me right in and did the compete service. The pads were getting a little thin but I knew we only had one more outing to go before we'd be storing the coach for the winter months. When I got my coach out of storage I replaced the brake calipers and pads on al four wheels. Traveling with my wife and sometimes one or more of my children or grandchildren I'm not willing to chance a brake failure if I can help to prevent it.
I would hope you feel the same way.
FYI, I do a complete brake service including a brake fluid change on my coach every other year without fail. That feeling you get in the pit of your stomach when you press the brake pedal and you keep rolling along will linger a long time in your memory bank if not forever.
I probably should also add, the brake fluid will remain in each caliper. It will not return to the master cylinder. As brake pads wear the caliper pistons move out of the caliper and stay there. There is no return system involved. Once the fluid is trapped in the caliper it will remain there until someone opens a bleeder and allows the fluid to escape. The caliper pistons will retract only slightly after the brake pedal is released. This is done by the seal on the caliper piston. The movement is very slight. Even the smallest amount of dirt can cause a piston to stop movement which will result in a brake drag condition.

MrMark52 · 06-19-2024, 01:44 PM

What LETMEGROW said x’s 2!

Isaac-1 · 06-19-2024, 03:32 PM

I just wanted to suggest you add a set of speed bleeders these are the ones I used on my P32 coach with dual piston calipers https://www.amazon.com/gp/product/B000CPIJOC/

Ron03Allegro · 06-21-2024, 11:12 AM

I will bleed all the calipers soon.
As far as serving brakes soon I will be repacking front wheel bearings I will do the fronts then. Rear I will wait,

Only thing that concerns me is the 2002 workhorse allegro 2003 does not have a manual emergency brake. It has a pull switch, how well will that work if needed? What happens when one pulls that going down the road?

LETMGROW · 06-22-2024, 07:13 AM

Quote:

Originally Posted by Ron03Allegro

I will bleed all the calipers soon.
As far as serving brakes soon I will be repacking front wheel bearings I will do the fronts then. Rear I will wait,

Only thing that concerns me is the 2002 workhorse allegro 2003 does not have a manual emergency brake. It has a pull switch, how well will that work if needed? What happens when one pulls that going down the road?

Pull that yellow knob which will try to stop the driveshaft from turning and you can plan on picking up a bushel basket of parts and pieces in the road. This brake was designed for holding a vehicle not for stopping a vehicle.
If you want to be safe don't hesitate. Bleed all four calipers ASAP and be done with it. If you can't find help, find a mobile repair service who knows how and can assist you in bleeding the entire system.
After rolling through an intersection due to no brake action and getting broadsided by an 18 wheeler you'll wonder why you waited if you make it through the crash.