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norcal_rdr

Replacing Trailer Brake Fluid

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norcal_rdr

I have an 08' Extreme trailer double axle trailer with brakes on both sides. I figure its a good time to do a little trailer maintenance since it is unknown if the previous owner did any and I have not done anything in the 8 months I have had it. From reading around it sounds like changing the fluid should be yearly. I opened up the master cylinder and sucked what I could out as a sample and its pretty nasty, almost green with some visible debris. I figure this means it needs a change.

From an old post this is about all the direction I can find given the tools on hand. I do have a vacuum pump, is the direction below the best way to replace the fluid?

"If you don't have a pressure bleeder, you can pull the old fluid out with a small hand held vacuum pump with a plastic canister (available at auto parts stores for $25.00). Do each wheel cylinder at a time (starting at the farthest first) and the fresh fluid will be sucked into the pump. Just remember to keep the master cylinder full during the process or air will enter the system."

This sounds so easy... is this really the case? If I do it this way what are the chances I will have to bleed the lines? Any instructions or input would be appreciated. Pic is of the fluid in there now.

IMG_1134.jpg

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hethj7

I haven't done it on my trailer either, so I can't speak to the process. But I will say do whatever you can to make sure the master cylinder stays full. I sucked air in while changing the fluid on my motorcycle back in college and it took FOREVER to get all the air out of the system. I don't know why, but what was supposed to be a simple job turned into a huge PITA (typical of a lot of my projects :cry: )

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Ndawg12

I'm interested to hear some ideas on how to introduce new fluid and bleeding the old fluid out without mixing the two and/or getting air into the system.

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scfdfireman

Hello all. One of my many jobs over the years was "fleet maintenance". During this time, I found that something as simple as flushing the brake fluid on an annual basis made a big difference in reducing brake component issues. Since then I’ve been flushing the brake fluid on all of our vehicles as an annual maintenance project and have never had a master cylinder or wheel cylinder issue.

I have a professional type of pressure bleeder and a bunch of master cylinder adapters, but you don’t have to be so sophisticated. For my classic Corvette (that uses silicone brake fluid) I use / made a pressure bleeder from a small sprayer from Home Depot. The sprayer holds about 2 quarts of fluid and has a built in pump on the top and costs under $10. Attach a hose to the spray tip (I think that I removed a plastic piece behind the spray tip to allow more flow) and from there to the master cylinder adapter. You don’t have to get too sophisticated for the master cylinder adapter… I’ve made one from 1/8” steel with rubber sheet glued to the bottom and a barbed fitting tapped into the top and a couple of bungee cords. Also, I use a collection bottle that helps to see the progress and reduces any mess. I made it from an old Snapple or Gatorade bottle and a clear 1/8” ID hose.

First, be careful with brake fluid (except silicone type) as it will damage paint if left on for any time, but it can be cleaned up with water or a damp rag if it happens.

You’ll first want to remove most of the old brake fluid from the master cylinder with a clean bulb syringe. Then refill it with new fluid and hook-up your adapter and sprayer that’s full of fluid. Pump up the sprayer until a few pounds are developed and look for leaks and correct them. Then go to your farthest wheel cylinder and just crack the bleed screw, then push the hose from your collection bottle over the fitting and turn it open at least 1 turn. You should see the dirty fluid coming out and eventually when it turns clear close the bleeder. The other wheel cylinders will go faster as the master cylinder and lines have already been flushed. Before removing the spray bottle or master cylinder adapters bleed of any remaining pressure from the spray bottle. Top of your master cylinder and clean up any remaining or spilt fluid. That’s it!

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a92harley92

I've done the "gravity method" on my vehicles. It's slow, but easy (and cheap) and can be done by yourself. Just open the master cylinder, open the bleeder(s), put a collection tube (tightly) over the bleeder(s) to route the fluid to a pan... and let 'er drip.

Don't let the master cylinder run dry, don't pour the fluid in too fast and cause air bubbles in the cylinder, and keep the top of the cylinder covered (but not sealed) so dirt/dust doesn't get in it.

You can also route your tube (attached to each bleeder) so that it goes up for a bit and then turns down to the pan. This keeps the bleeder outlet submerged at all times so you can see if any air bubbles are coming out.

I haven't tried this method with my boat trailer, but I'm guessing it would work the same.

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tvano

You don't have to get too sophisticated for the master cylinder adapter…

just where on the master cylinder does this jury rigged adapter get attached?

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Ndawg12

Hello all. One of my many jobs over the years was "fleet maintenance". During this time, I found that something as simple as flushing the brake fluid on an annual basis made a big difference in reducing brake component issues. Since then I've been flushing the brake fluid on all of our vehicles as an annual maintenance project and have never had a master cylinder or wheel cylinder issue.

I have a professional type of pressure bleeder and a bunch of master cylinder adapters, but you don't have to be so sophisticated. For my classic Corvette (that uses silicone brake fluid) I use / made a pressure bleeder from a small sprayer from Home Depot. The sprayer holds about 2 quarts of fluid and has a built in pump on the top and costs under $10. Attach a hose to the spray tip (I think that I removed a plastic piece behind the spray tip to allow more flow) and from there to the master cylinder adapter. You don't have to get too sophisticated for the master cylinder adapter… I've made one from 1/8" steel with rubber sheet glued to the bottom and a barbed fitting tapped into the top and a couple of bungee cords. Also, I use a collection bottle that helps to see the progress and reduces any mess. I made it from an old Snapple or Gatorade bottle and a clear 1/8" ID hose.

First, be careful with brake fluid (except silicone type) as it will damage paint if left on for any time, but it can be cleaned up with water or a damp rag if it happens.

You'll first want to remove most of the old brake fluid from the master cylinder with a clean bulb syringe. Then refill it with new fluid and hook-up your adapter and sprayer that's full of fluid. Pump up the sprayer until a few pounds are developed and look for leaks and correct them. Then go to your farthest wheel cylinder and just crack the bleed screw, then push the hose from your collection bottle over the fitting and turn it open at least 1 turn. You should see the dirty fluid coming out and eventually when it turns clear close the bleeder. The other wheel cylinders will go faster as the master cylinder and lines have already been flushed. Before removing the spray bottle or master cylinder adapters bleed of any remaining pressure from the spray bottle. Top of your master cylinder and clean up any remaining or spilt fluid. That's it!

just where on the master cylinder does this jury rigged adapter get attached?

I really like this idea but like Tvano, I'm having a hard time visualizing a couple things. Are you talking about something like a pump sprayer?

chapin_20000.jpg

And what kind of adapter fits the nozzle and the orfice of the master cylinder? Does something like that provide enough pressure to move brake fluid all the way through the lines?

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Lance B. Johnson

The comment about gravity bleeding.... I don't know why more people don't do it this way.... It's so easy just pop the cap on the m/c, then crack the bleeder and let it flow into a pan. Once in awhile top off the reservoir. No special tools required. I use this method on probably 100 percent of the vehicles I work on.

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Bobby Light

Hey Ruff can you do a brake bleeding writeup for us and maybe include a couple pics? I'd like to do this job this winter as well.

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Malibu_Mike

Check out this motive products, My link I rented a hand bleeder from the local auto parts store, and keep running out out fluid, which injected air into the lines. And after too many attempts :crazy: and pulling all my hair out. I broke down and bought one of these, it works great, and is so simple. You can fill it half way and do several trailers without ever getting air in the line. This is a great tool, since it's pressure driven by the pump, you can also leave it hooked up for several minutes and tell if you have a link in a line which was part of my original problem, and it makes it easier to find. :thumbup: It also makes the whole process take a matter of minutes, start with the furtherest brake and work towards the closest. With a creeper you can stay under the trailer till all 4 brakes are bleed, without having to check the level. You can also force all your old fluid out very easy.

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scfdfireman

The master cylinder adapter can be made from anything that makes a tight seal on the top. A big rubber plug with a hole for the supply line or a hand made steel adapter like I use will work. If I get a chance, I'll take a picture of my adapters.. The sprayer that I used is the one shown below... The gravity method works, but is very slow and may not develop enough pressure to push out some air or debris. The garden sprayer will develop a few pounds and works well.

http://www.homedepot...catalogId=10053

post-1873-060563700 1321373046_thumb.jpg

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a92harley92

The comment about gravity bleeding.... I don't know why more people don't do it this way.... It's so easy just pop the cap on the m/c, then crack the bleeder and let it flow into a pan. Once in awhile top off the reservoir. No special tools required. I use this method on probably 100 percent of the vehicles I work on.

I know!

The "power bleeder" and "vacuum pump bleeder" kits work... I've used them both... and they do a faster job (once you get all the adapters and everything set up)... BUT the gravity bleed kit costs between $0 - $2 ($2 kit includes a piece of nylon tubing to fit over the bleeder to route the fluid to a catch pan so the fluid doesn't get all over the wheel, tire, and floor).

Pretty simple... pretty cheap.

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dalt1

Not that difficult to bleed as the manual suggests. 2 people needed though. 1 to manually stroke the Master Cylinder and 1 to open and close the bleeder valves. I have had my son assist when he was only nine or ten. Don't know that gravity feed would work as my steel brake lines have a loop that raise them above the actuator.

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a92harley92

Don't know that gravity feed would work as my steel brake lines have a loop that raise them above the actuator.

Ahhh! You may have a point. I guess it depends on how much line is above the master cylinder. The siphon effect would overcome some of that? :unsure:

Maybe one could raise the tongue of the trailer up so that the master cylinder is the highest part of the brake system.

Edited by a92harley92

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Lance B. Johnson

Not that difficult to bleed as the manual suggests. 2 people needed though. 1 to manually stroke the Master Cylinder and 1 to open and close the bleeder valves. I have had my son assist when he was only nine or ten. Don't know that gravity feed would work as my steel brake lines have a loop that raise them above the actuator.

right....that could put a kink in things...

When I am working with cars I think the gravity method is faster....I always am working on something else and bleeding the brakes at the same time.....just a side note.

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