Bleed your brakes discussion

[andy29847]

I've owned my 2001 38 FDDS for 3 years. It's been a good RV for me and I have enjoyed my travels.

I like to do my own maintenance work. When I first got the camper, I tried to bleed the brakes. The front worked OK, but the driver's rear would not bleed. I took my camper to a local shop, and they were able to bleed the brakes by manually opening the solenoid in the ABS modulator, using a PC with a Cummins program. I was happy with my brakes for the next 6 months, but then, at the end of a trip, I felt the pedal go soft after long downhill. The brakes came back, but I knew I need a full brake inspection.

I went back to the same shop (I like to go to this shop because he lets me look over his shoulder). We pulled off the wheels and found some heat damage on the passenger front side. The brake disc had cracks, and the ABS sensor was burnt. We found another brake disc with cracks, and we also found that the driver's rear wasn't working. Also, the ABS modulator was showing a trouble code for an open conductor to a solenoid (a common trouble with the ABS modulators of this type). Several thousand dollars later, I had new brake discs, new calipers, new brake pads, and a new ABS modulator. Thank goodness for maintenance plans! The coach has run and stopped perfectly since this repair. Based on my problems, and what I have read about issues with Alpine RV brakes, I have decided to replace my brake fluid yearly. Today was my day for 2020.

I work alone, so I need a tool to help me bleed the brakes. I already had a Motive Performance Power Bleeder for my Jeep and I used that. A happy coincidence is the the Chrysler kit that works for the Jeep works for the Alpine coach too.

https://www.jegs.com/i/Motive+Produc...CABEgIz-vD_BwE

I like the power bleeder because I can load it with 2 quarts of brake fluid and I don't have to worry so much about running out of fluid when I am under the coach.

I started with the Passenger front. That's different than what I've read in other articles. I picked the passenger front because it is the longest run from the master cylinder to a brake.



I removed the old fluid from the master cylinder, and filled it with new fluid. It took quart bottle of new fluid to fill the master cylinder. I pumped the power bleeder to 20 pounds and went under the coach to work. When you open the bleeder fitting on the caliper, the fluid comes out slow and steady. I used that Motive Product Catch Bottle ( https://www.jegs.com/i/Motive-Produc.../1810/10002/-1 ) to capture the old fluid. I took 2 full catch bottles from the passenger front before I was satisfied I had new fluid. The driver's front was next, and I removed a catch bottle of fluid there. I drained a catch bottle from the passenger rear, and then a 1/2 catch bottle from the driver's rear.

I checked my power bleeder between wheels to make sure I had enough fluid, and to pump the pressure back to 20 pounds. Counting the fluid left over in the bleeder, I used 3 1/2 quarts of brake fluid for the job.

Comments and suggestions are invited.

[Ray,IN]

Good job! You are one of the few who know most hydraulic brake systems recommend replacing old brake fluid with new on a set schedule. Nearly all European auto makers do, Ford does, that's all I remember of U.S.A. mfgrs.

[Old Scout]

Nice write up--my compliments....some thoughts: 1- depending on residence/location, annual flushing might be excessive for some of us but certainly no more than three years; 2-assume you have 4-piston calipers on a 2001?????--you didn't mention removing the wheels so how do you reach the outside bleed screws. The fronts are doable, maybe, but the rear wheels are physically impossible to reach--at least on my 2003????; and 3-very interesting--I too thought rear wheels were farthest from master cylinder but never thought about the routing thru the ABS module......learn something new everyday!!!!!!
PS--I use a hand-held vacuum pump at the bleed screw--closing the screw when/if catch bottle is full....cheap but more hassle to use....
PSS--I have bleed brakes on perhaps 7-8 different Alpines over the years. I almost always find evidence of moisture [rust] on the rear bleed screws but never on the front screws.....

[andy29847]

Originally Posted by Old Scout

2-assume you have 4-piston calipers on a 2001?????--you didn't mention removing the wheels so how do you reach the outside bleed screws. The fronts are doable, maybe, but the rear wheels are physically impossible to reach--at least on my 2003????; and 3-very interesting--I too thought rear wheels were farthest from master cylinder but never thought about the routing thru the ABS module......learn something new everyday!!!!!!

The calipers on my RV are the Bosch 73mm 2 piston calipers #4153222. They only have one bleed port. I do not have to take the wheels off to bleed the brakes.

About which wheel to bleed first...I went with the passenger front because it was the longest path. However, I think that when the brake system is configured like my Alpine, with the ABS Modulator in a remote location, it probably doesn't matter which wheel goes first as long as I pump enough brake fluid through on the first wheel to clear the line between the master cylinder and the ABS modulator.

The fluid that came out was mildly discolored. It might have been good for another year, but my coach has been sitting still a lot while I recovered from an illness. Then, as soon as I got well, the world changed, and there's nowhere to go.

About Alpine Coach brakes: I read all I could find before doing the "big" brake job on my coach. I believe there were at least 3 different configurations in the early years. First was the Bosch caliper with 2 67mm pistons. The vehicles with this caliper went through a NTSB recall. 2nd is vehicles like mine that have the Bosch calipers with 2 73mm pistons. These were never recalled. Then there are the coaches with 4 piston calipers. I have not seen one of these. As I understand it, the biggest issue with the early calipers was the coating on the pistons. When the brake fluid got contaminated, the coating would swell and the piston would stick. One of the reason I changed calipers when I had my brakes done was to go with a caliper that had all metal pistons.

Thanks for your note. Your feedback on the threads in this forum is always valuable.

[Old Scout]

Great feedback....my 2003 has a BOD of Feb 2002 and has 4-piston calipers. Wasn't aware of the two versions of the 2-piston model....knew the 2-piston version was susceptible to both internal moisture and external slide pin rust/pad freeze-up. As a result, periodic inspection and maintenance are essential. Quite a few threads about 2-piston failures, very few on 4-piston [excluding the later MC pedal pressure issue]. Never had the "pleasure" of working on a 2-piston system....safe travels....

[andy29847]

When I was looking for information about disc brake maintenance, I found these 2 files.

Pin slide Disc Brake manual - http://www.weindex.info/pdf/Brake/2.pdf

Bosch Brake Parts - http://workhorseservice.com/wp-conte...rake-Parts.pdf

[whalepirot]

How do you get the ABS valving to open?


I've bled auto brake many times, but ABS throws a kink in the works, as typically some e-device is required to open the ABS valves; a device I don't have for any ABS car.


I suppose, as the coach is driven, any old fluid in the ABS will get diluted by new,; not great procedure, as I suspect moisture (rust) can freeze those valves, just as in wheel components.

[Alpine36]

No special tools required to bleed with ABS.
Well maybe one, your wifes foot. Shes pretty special. I bled ours with the key/engine off, no issues. This will activate the 12v booster pump, so little pedal effort required. BTW, it's a good idea to exercise that pump monthly.
After our first road trip I simply emptied the reservoir and refilled. Thats going to be an annual maintenance item. Cheap insurance.

[andy29847]

Originally Posted by whalepirot

How do you get the ABS valving to open?
I've bled auto brake many times, but ABS throws a kink in the works, as typically some e-device is required to open the ABS valves; a device I don't have for any ABS car.

I suppose, as the coach is driven, any old fluid in the ABS will get diluted by new,; not great procedure, as I suspect moisture (rust) can freeze those valves, just as in wheel components.

The only time an e-device was required to bleed the brakes on my coach was when the ABS modulator was bad. The first time that happened, the driver's rear would not bleed. My tech could open the line with a computer, but he thought the modulator was bad. The brake system was NOT giving a trouble code. The second time I had trouble bleeding the brakes, there was a trouble code (open conductor to solenoid is what I remember) and the ABS modulator was replaced. Internet research finds this is not an unusual issue.

[andy29847]

Originally Posted by Alpine36

No special tools required to bleed with ABS.
Well maybe one, your wifes foot. Shes pretty special. I bled ours with the key/engine off, no issues. This will activate the 12v booster pump, so little pedal effort required. BTW, it's a good idea to exercise that pump monthly.
After our first road trip I simply emptied the reservoir and refilled. Thats going to be an annual maintenance item. Cheap insurance.

My thinking on manually bleeding brakes was changed a couple of years ago. This information came from a very well respected mechanic.


Hook up your tube and catch bottle

Crack open the bleed screw (fluid will seep out by gravity alone)

have your assistant press the brake pedal to the floor and hold it

close the bleeder screw

release the brake pedal

repeat.

This expert states that he prefers to bleed brakes manually because the sudden flow of fluid tends to better cleanse debris out of the system than the slow steady flow of a power bleeder.

[Old Scout]

….the only concern I have with the "pedal pumping" method is that if you don't time your bleed screw closing with the DW's pedal pumps, you do increase the risk of introducing air into the system??????

[Alpine36]

Originally Posted by andy29847

My thinking on manually bleeding brakes was changed a couple of years ago. This information came from a very well respected mechanic.


Hook up your tube and catch bottle

Crack open the bleed screw (fluid will seep out by gravity alone)

have your assistant press the brake pedal to the floor and hold it

close the bleeder screw

release the brake pedal

repeat.

This expert states that he prefers to bleed brakes manually because the sudden flow of fluid tends to better cleanse debris out of the system than the slow steady flow of a power bleeder.

Thats exactly the correct way to bleed them.
Foot pressure only with the key off. Key on will usually throw an ABS code.

[Ljwt330]

Originally Posted by Alpine36

Thats exactly the correct way to bleed them.
Foot pressure only with the key off. Key on will usually throw an ABS code.

The only thing to add, IMO, is that the pedal pressure should be slow and steady, not a sudden stomp to the floor.

[Alpine36]

I always close the bleeder before I say "up", just as you start to see the stream slow down a bit. No need to pump, just even, light, steady pedal pressure.
Clear hose into an old hub cap works for me. Easy to see when its running clear. Bottles work good too but I know I'd just tip it over eventually lol.
Shes pretty well versed in helping bleed brakes some 35 years and many projects later. Just a ramdom picture or two of todays social distancing with the neighbor boys. About 1500 feet above Hood Canal and Lake Cushman in my backyard. Be safe y'all.