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Brake Fluid Bleed / Flush / Change Procedure

Ah brake fluid, it can be a somewhat controversial topic. Some people never change the fluid, some people change it every year. There is a variety of thoughts on the matter. Personally I like to change or flush the brake fluid when it's due for a change. To me, that's not at a defined time period. I've got a 3-year old car with like-new fluid, I checked it.

By far one of the easiest ways to properly test your brake fluid is to use the Brake Check Dip Sticks. You can order them here from Also, buy some Motorcraft DOT3 brake fluid as well.

OK, so you're looking at $50-75 for a tube of test strips, a little pricey but it comes with 100 strips so you can test your fluid once or twice a year on all your vehicles, and your buddies' vehicles too. I figured that even after spending that money once, it's still cheaper than having the dealer flush my brake fluid once.

Do I need to change my fluid?

So first off let's see if your fluid needs to be changed. If you know your fluid hasn't been changed or flushed in the last 5 years or more, it's probably a good idea to do it anyway. Brake fluid absorbs moisture and that wrecks all sorts of things like ABS parts, and flushing your brake fluid can be a lot cheaper than replacing parts later down the road. Can you tell I'm a big fan of preventative maintenance? LOL

I have the service records since day 1 for my 1996 Thunderbird. The brakes were replaced back a few years ago and the previous owner was charged $50 for a flush of fluid. Well the fluid is still totally black so I suspect they did a quick bleed and called it a day (no true flush of the fluid). So that means the majority of the fluid in the system is 17 years old. Overdue. The process is easy with the test strips, just dip it in the fluid for a second or two, take it out, shake off the excess, and wait 60-120 seconds. Here are a few photos of the process:

Dip the brake fluid test strip in the master cylinder after cleaning and removing the cover:

Brake Fluid Test Strip

Wait 60-120 seconds and compare the strip color with the side of the brake strips tin:

Brake Fluid Test Strip Results

So as you can see, the brake fluid condition is pretty much into that "required service" area. No matter, I'm flushing / changing the fluid anyway. The main reason for me bleeding the brakes here anyway is the spongy brake pedal I've had since I got the car. Since I know the brakes weren't properly flushed by the fly-by-night brake shop by the previous owner, I suspect there could be air in the ABS system somewhere which is causing the spongy pedal feel.

OK, so how do I flush it?

OK, well if your Thunderbird or Cougar has ABS brakes (Anti-lock Braking System), you may or may not need a special tool to properly bleed the ABS valves in the ABS control unit (HCU). My car does have ABS so the procedure I'm going to do next may apply to you.

To be fair, some guys with ABS report that they bled their brakes just fine the old fashioned way, without using this tool. From what I can tell you will need this tool if you have replaced anything near that ABS valve unit. I don't know but you may also need this tool if you replace the master cylinder.

There are two ABS tools that accomplish this function. The first tool is the Ford Rotunda T90P-50-ALA Teves Anti-Lock Brake Harness. This is a black metal box with connector pins and everything you need to properly activate the ABS valves to bleed air from them.

I bought the tool used from another Ford forum from an owner there. These also come up for sale from time-to-time on eBay. Expect to pay in the $125-$200 area. The good thing is when you're done you can sell the tool and get most of your money back. The T90P-50-ALA tool is also used on Bronco, F-150, Taurus, Town Car, and Continentals.

One quote I found on the 'net regarding that tool is this:

The tool cycles fluid from the master cylinder reservoir to the HCU and back to the reservoir. Fluid never overflows the master cylinder reservoir. Think of the tool like your car's waterpump - it cycles coolant throughout the engine while keeping all the coolant contained. The reason I sucked old fluid out of the reservoir and replaced it with fresh fluid before using the tool is because I wanted to replace all the fluid in the HCU. If you don't do this (remove and replace fluid) then you are only bleeding air (if there is any) out of the HCU.

Here are two photos of the tool:

Ford T90P-50-ALA Teves ABS Tool

Ford ABS Tool

The other tool which I have no experience with is the Thexton 133 TEVES IV Brake Bleeder Tool. It is an aftermarket tool that is cheaper because it's simpler and a little less robust.

It is no longer in production and in my experience is even harder to buy. Here's a photo of it:

Thexton 133 Tool
Picture courtesy of

OK, let's move on. So what I did first was use a vacuum pump to first clear out all the old nasty fluid from the master cylinder reservoir. You could use a turkey baster but expect more spills. Remember brake fluid will eat through paint so you really want to keep things neat here.

Using vacuum pump to suck out old brake fluid from reservoir:

Vacuum pump

Pumping old brake fluid out

After that's done, add some nice fresh new Motorcraft DOT 3 brake fluid. Here is the fluid (I bought 3 small jugs), and a nice action shot of me filling the master cylinder reservoir back up:

New Motorcraft Brake Fluid DOT3 CPM-1-C

Refill master cylinder fresh fluid

OK if you haven't done so already, it's time to jack up the car, support it by jack stands all around, and remove all the wheels and tires.

So now I'm ready to use that T90P-50-ALA tool. To get access to the wiring connector where the tool plugs in, you'll need to remove the driver's side front fender liner. There are about 5 screws and about 5 plastic clips, sorry I don't have a picture of the removal process, but here is where much of the ABS stuff is located. The arrow points to the wiring block that you need to disconnect and connect up to the tool.

Ford Thunderbird Mercury Cougar ABS Location

This part is fairly easy. Start by lifting up the metal clip you see there, it swings up, which allows you to pull our the wiring harness pull out the top first, and rotate it kind of down and toward you, and that lets you take the bottom of it out. When you're done you should have the harness in your hand.

ABS wiring harness remvoed

Next step, plug the T90P-50-ALA tool in the same kind of way you took the harness out. You need to put the bottom part in the bracket and kind of swing the tool/harness up to fully seat it. It's kind of hard to explain but if you're doing it with the tool in front of you, you'll know what I mean.

Connect Ford TEVES ABS tool

You may hear a noise from the ABS stuff when you initially plug the tool in, don't worry about it. The tool's instructions on the back state:

- Connect the 55-pin vehicle harness to the T90P-50-ALA Harness
- Slide the switch to the BLEED position, turn vehicle ignition to ON
- Press the START button
- After 20 seconds depress and hold the VALVE button for 20 seconds
- Wait for OFF indicator to illuminate, turn OFF vehicle ignition, disconnect vehicle harness from the T90P-50-ALA and connect to the Electronic Control Unit
-Refer to the proper vehicle service manual for detailed procedures
NOTE: To turn off the pump motor during the bleed operation, depress the ABORT button

Well those instructions are accurate, and easy. I used my wristwatch to time the three 20 second intervals, I think it took a little over a minute total but it was all good.

Here are pictures of the process:

In this step it's connected and ready. The red OFF LED is illuminated

ABS Tool Ready

OK, here I've pressed START so the green ON LED is illuminated and the ABS stuff is doing it's thing

ABS tool started and working

After 20 seconds I held down the VALVES button, shown here:

Press the valves button on the tool

And here it is again after the entire procedure is done:

ABS tool done

The bad news was after I used the tool, the fresh new fluid in the master cylinder was all dirty again. So clearly the tool did activate the valves and must have sucked some of that good fluid down through the ABS HCU which is good and so my next step was to pump out the master cylinder reservoir again, and refill it again with fresh new fluid.

Well, that's it. If you use that special ABS bleeding tool, you only need it for about 60 seconds. That was an expensive 60 seconds, heck it took longer to remove the fender shield LOL Alright, time to turn the ignition off, remove the tool, and reconnect the harness to the factory ABS stuff.

So obviously you should refer to your car's service manual to find the correct order in which to bleed your brakes. For 1996 Thunderbird & Cougars (and probably 1997 and 1995, maybe even 1994 models as well), the order is this:

  1. Right Rear
  2. Left Front
  3. Left Rear
  4. Right Front

There are a few different ways to bleed your brakes. There's the vacuum method where you hook up that vacuum pump at the bleed screws and suck the fluid out. There's the pressure method where you pressurize the master cylinder with a special tool and it forces fluid through the system from that end. I chose the old fashioned two-person manual bleeding method. The factory service manual covers it pretty well here:

The primary right front and left rear and secondary left front and right rear hydraulic brake systems are individual systems and are bled separately. Bleed the longest line first on the individual system being serviced. During the complete bleeding operation, DO NOT allow the brake master cylinder reservoir to run dry. Keep the brake master cylinder reservoir filled with High Performance DOT-3 Brake Fluid C6AZ-19542-AA or DOT-3 equivalent meeting Ford specification ESA-M6C25-A. Never reuse brake fluid that has been drained from the hydraulic system or has been allowed to stand in an open container for an extended period of time.

NOTE: On vehicles which have the brake master cylinder mounted at an angle to the horizontal, bleeding may be better performed if the vehicle is positioned so that the brake master cylinder is horizontal.

1. To bleed the brake system, position a suitable box wrench on the bleeder fitting on the rear brake assembly wheel cylinder. Attach a rubber drain tube to the wheel cylinder bleeder screw. The end of the rube should fit snugly around the wheel cylinder bleeder screw.

2. Submerge the free end of the tube in a container partially filled with clean brake fluid and loosen the wheel cylinder bleeder screw approximately three-quarter turn.

3. Have an assistant push the brake pedal down slowly through its full travel. Close the wheel cylinder bleeder screw, then return the brake pedal to the full release position. Repeat this operation until air bubbles cease to appear at the submerged end of the bleeder tube.

4. When the fluid is completely free of air bubbles, secure the wheel cylinder bleeder screw and remove the bleeder tube.

5. Repeat this procedure at the brake assembly on the opposite side. Refill the brake master cylinder reservoir after each wheel cylinder is bled and install the brake master cylinder filler cap and gasket. Make sure the diaphragm-type gasket is properly positioned in the brake master cylinder filler cap. When the bleeding operation is completed, the fluid level should be at the MAX line to 4.0 mm (0.16 inch) below.

6. Repeat Steps 1 through 5 on the system not yet bled.

7. After disc brake service, make sure that the disc brake pistons are returned to their normal positions and the brake shoe and lining assemblies are properly seated. This is accomplished by applying the brake pedal several times until normal pedal travel is established.

8. Check pedal feel. If brake pedal feels spongy, repeat bleed procedure.

Here are a few pictures from my brake bleeding process. You can see what a brake bleeder screw looks like here in the dead center of the photo, I have removed the rubber dust cap already, you can see the "nipple" that you attach a hose to. It doesn't hurt to spray a little WD40 or other penetrating fluid before you plan on doing this, in case the screws are rusted in a bit.

Brake bleeder screw location

And here's the setup with the wrench on the bleeder screw, hose, connected down to a catch container.

Brake bleeding procedure

Here is all the old nasty brake fluid that I flushed out of the system. GROSS! That was pretty much clear at one time.... Be sure to dispose of used brake fluid properly!

Dirty old brake fluid gross

And here is the master cylinder with fresh new fluid. The new fluid is almost totally clear, it looks MUCH better now!

Fresh fluid in master cylinder, it looks like new

Good luck with your brake change / flush procedure, I hope this helped.

Check out the other Thunderbird/Cougar articles we have:

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