Changing Brake Fluid...Here's how!! - Diesel Truck Forum -
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post #1 of 11 (permalink) Old 07-18-2005, 01:40 AM Thread Starter
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Thumbs up Changing Brake Fluid...Here's how!!

After doing some investigation...I decided that I really needed to change the brake fluid in my truck. Its probably still the same fluid it came with from the factory. Its now recommended that the fluid get changed every couple of years or so...or around 30k miles. Brake fluid absorbs water...which keeps the inside of the brake lines from rusting...but it begins to lower the boiling point of the brake fluid. It may get to the point where in a panic stop you hit the brakes...the water in the fluid turns to steam...steam compresses...and suddenly you have no brakes. Not good.

I found all sorts information on the net about changing the fluid...but nobody had pictures or provided information like wrench size...tubing size...etc. So...thats what this thread will include.

The first thing I did was crawl under the truck and spray some WD-40 on all the bleeder valves. I didn't want to run the risk of breaking any of them when I tried to loosen them. You can see where the bleeder valve is here. This is the right rear caliper. The tubing that I used had an ID of 3/16" and an OD of 5/16". You will need a 10mm box end 6 point wrench to loosen up the valve. I used a 6 pt 10mm socket because I didn't have the wrench. Once loosened...a 10mm open wrench works fine.

I also picked up 2 bottles of Valvoline synthetic brake fluid. It exceeds Dot 3 & 4 requirements. This stuff has a dry boiling point of 480 degrees F and a mimimun wet boiling point of 330 degrees F. My Advance Auto had it on sale for $5 for 32 ounces. DO NOT use DOT 5 stuff in our brake system!!!

First things first. I used a vet syringe to draw the old fluid out of the master cylinder. This is how it looks. I figure I drew out 22 to 24 ounces of old brake fluid. This is a side by side comparison of old fluid to new fluid. Yuck!!

Once that was was time to enlist the help of my wife. I needed someone to pump the brake pedal to build pressure...then hold the brake pedal about 1/2 way down while I bled the brake system. You start at the right rear...then go to the left rear...then the right front...and finsh with the left front. This was my 'el cheapo collection system. You need clean fluid in the bottom of your collection bottle...just in case you don't close the bleeder fast enough and vacuum draws the fluid back up. I had 3 feet of tubing...which was a bit too long. 2.5 feet would have worked better. I had the wife pump the brakes...hold pressure...then I cracked open the bleeder valve with the 10mm open wrench...counted to 5...then closed it and had the wife release pressure. You repeat this cycle over and over until the clear brake fluid runs out of the bleeder valve. The right rear took the get clear fluid to run out.

It took about 50 minutes total to get through all the brakes. I'm guessing that it also took around 45 ounces to get the clean fluid through the entire system.

After seeing my old fluid...I am really glad that I got this done when I did. I tow a bit heavy with the camper...and now know that my fluid is up to the task.


On edit...Got a chance to drive the truck. Brake pedal definately has a more firm feel to it. truck used to "bunny hop" when slowing down from highway speeds. About 75% of that is now gone. I was always chocking it up to warped rotors...but maybe the brake fluid was just getting to old.
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post #2 of 11 (permalink) Old 07-18-2005, 11:30 AM
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Nice write up, and good to know.. I have never changed brake fluid... Even on vehicles well over 100K....
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post #3 of 11 (permalink) Old 07-18-2005, 01:29 PM
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Good write up Dave and yes thats another Entry into the F.A.S.S. Drawing..


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post #4 of 11 (permalink) Old 07-23-2005, 03:28 AM
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This is a good post and a good thing to promote. Changing brake fluid is often overlooked, but is an advised service procedure from many manufacturers. It is recommended that the fluid be changed in the spring, after the wide temperature fluctuations of winter driving are over, which causes the system to pick up that fluid-destroying moisture. I use a shop vac for things like brake fluid and power steering fluid-hey, heres another how-to idea for the drawing!
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post #5 of 11 (permalink) Old 01-29-2006, 07:15 PM
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Great post and great pics.

Ford does not even recommend changing fluid unless a brake job is being performed. My local dealer doesn't even list it as a "payable" job if one just wants the fluid done!!!

I flush once a year regardless and mine looked just at black as this user showed. It's cheap, easy and fun to do... plus the satisfaction that clean fresh fluid is safer and better for your trucks braking system.
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post #6 of 11 (permalink) Old 01-30-2006, 05:31 PM
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The only part you missed was bleeding the ABS unit. There used to be a service too to bleed the unit, but I don't think you guys would have access to it.
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post #7 of 11 (permalink) Old 03-26-2007, 02:59 PM
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Great post!!!!!!!!!! Brake fluid is probably the most neglected fluid in a vehicle.
have changed mine religously in every vehicle have ever owned. well done!
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post #8 of 11 (permalink) Old 11-08-2007, 08:42 PM
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There is an easier way to bleed... make sure your master cylinder is topped off and but a clear tube on each bleeder valve and have it running into a pan.. Crack all the lines and just let gravity do its thing... Keep an eye on your master cylinder and when it starts to get low just keep adding new fluid to it... continue to do this until you have clear fluid run out of each line... I did this the other day on my car and it only took about 20-30 mins...

Aaron - 2004 F350 "Offroad Edition"

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post #9 of 11 (permalink) Old 11-09-2007, 06:33 AM
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Bleeder screws are normal service parts, if they are rusty get new ones.
If they use mag chloride for snow use No-Seize on the threads only in a small amount. Make sure that none is on the tip.
They make a vacuum pump and container to suck the fluid from the bleeder screw- it is about the same as pressure bleeding with 12 # pressure.

The container is easy to make - use a jar that the level can be seen in that will stand vacuum with a screw on lid. Drill 2 holes in the lid 1/64 smaller than the tubing. cut the end of the tubing at a shallow angle so it will pull through the smaller hole. one tube to brake bleeder screw and the other to the vacuum pump with a pair of Vice Grips to pinch the flow off. Tapping the inlet on the air compressor will provide a vacuum pump for a short time. Or use a hand vacuum pump that is used for testing.

Even sucking the MC out with a turkey baster will change 1/2 of the system volume and by next oil change it will be mixed so it can be changed by dilution.


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post #10 of 11 (permalink) Old 09-11-2011, 04:23 PM
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I have done a few units where I bleed out the fluid to clean the master Cylinder, some are very disgusting, I just did a motor home the sediment was chocolate brown, the fluid very dark.
The only problem with bleeding the system is you do not get the fluid out of the calipers, Most systems the hose comes in the top section near the bleeder.
You could clamp off the hose, open the bleeder and collapse the caliper, that would get a larger percentage.
The only way to get all the fluid changed is to dismantle the calipers and cylinders, then reseal and refill, or replace them. Being sure you flush the old fluid out before you connect the new calipers.
If you have ever taken an old caliper apart they have a lot of rusty grit in them.
Just a thought!

1988 ford van fresh overhaul, 1991 nissan pick-up 1993 Caprice 2000 GMC S10 Blaser 2007 nbs 3500 GMC 4x4 crew-cab long box 17 inch single wheels Duramax Alison. BW turnover Ball. Furakawa FL35 loader. Retired, HD mechanic, worked on engines all my life. Fabricator welder. electrician. in the process of finishing my new shop. Live in Rock Creek B.C. Wife has a fruit stand.
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