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  #1  
Old 03-07-2003, 03:45 PM
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Quick question about brake pressure bleeders

I have a '98 W210 wagon and just purchased the Motive Pressure bleeder tool and will use it to flush my brake fluid.

The old brake fluid in the reservoir is 2 years old but looks clear, new and the same color as fresh fluid I purchased.

My question is, if the color of the old and new fluid are the same, how will I know when the old fluid has been pushed through the system and new fluid is making its way out of the bleeder screw?

I seem to recall someone talking about a reasonable duration for the bleeder screw to be open that would ensure that all the old fluid was out (right-rear wheel).

Anyone have a magic number?

How about a PSI for pressure bleeder?

Thanks in advance.
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  #2  
Old 03-07-2003, 03:59 PM
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A pro named Stu Ritter from the Ritter-Easley list once stated that pushing a qt. thru was good enough. Just to be sure, I always pour 1.5 qts. into my pressure tank before starting the flushing process.

When it gets near, but not at the end, I start closing down the bleeder valves.
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  #3  
Old 03-07-2003, 04:31 PM
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Mike, I'm curious, are you opening all the bleed valves at the same time when you flush?? If you are I thought that was not the way to go.
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  #4  
Old 03-07-2003, 04:40 PM
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I got the same impression as Early Bird. If that is what you are doing, that is NOT a good thing.

Use something to empty the reservoir, pour at least a quart of fresh fluid in the gadget, connect the gadget, check for good seal and pump it up. Then open each bleed screw one at a time and let it flow for a little bit, then close that screw. You will get an idea of how long to leave it open after a few wheels.

Start at the left front, then right front, left rear and right rear. This way you are moving the dirty fluid out of the closest caliper first so that it doesn't contaminate the fluid that is going to the next one down the line.

If your fluid has not been changed in two years, I'm quite confident that once you pump through a quart, it will be a lighter color in the reservoir than when you started. Totally clean fluid is almost completely clear with hardly any brown tint at all.

Good luck,
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  #5  
Old 03-07-2003, 04:42 PM
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I think I saw the number 250 ml for each wheel. This may be overkill, since not all lines in the circuit are equal length-- or it may simply be a neat number to divide the liter that the fluid comes in.
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  #6  
Old 03-07-2003, 04:54 PM
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Larry, I believe in you, but my question is you said start from the left front caliper when its always been said by the Pro's to start from the right rear. What gives??????
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  #7  
Old 03-07-2003, 05:16 PM
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All bleeeder valves are opened at once in shops that use pressure bleeders. Seen it done that way more than once. Works for me.
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  #8  
Old 03-07-2003, 05:32 PM
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I just tried out my new Motive a couple of nights ago. I ran almost a quart through, and used a container with volume marks to measure approximately 4 oz. each wheel - more at the rears than the fronts.

My procedure was to start with the wheel furthest away (RR) from the master cylinder. I read somewhere that was the way to do it. I started each wheel at 20 psi and pumped it back up before doing the next.

If you have two-year old fluid, I would definitely siphon it out of the master and refill, rather than pushing it through the system.
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  #9  
Old 03-07-2003, 05:44 PM
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IF you are interested, Ate makes Super Blue & Type 200 brake fluid. Switch from one to the other every 2 years so you go from blue to gold, then back to blue - easier to tell when all the old fluid is out. For the ABS on my '87 30 psi is specified in the shop manual to properly bleed thru the ABS controller. Not sure about newer models.
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  #10  
Old 03-07-2003, 05:56 PM
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I did a lousy job of explaining my position on this in the last post I made. I'll start over.

Larry seems to believe that opening all bleeders at once is not a good idea. In the case of these home-style bleeders that you buy for $50-$100, he's likely correct.

Many of these DIYER units will not pump up "safely" much higher than 20 lbs. Some pros say that you need at least 30 lbs to bleed ABS systems.

I've been inside specialty brake shops and have seen them put a car up on a rack, place a bucket under each wheel, connect a "real" presure bleeder, then open up all 4 bleeder valves at once. Alot gets pushed through and afterwards, you've got a rock-hard brake pedal. These shop pressure bleeders pump up alot higher than the $50 DIYER variety.

Using one of these DIYER bleeders that really doesn't pressurize that well, opening all 4 bleeders at once is not going to build enough pressure. I agree.

What this does do is push all of the fluid out in a somewhat equalized fashion. 15-20 lbs of pressure will "flush" just fine. I'll easily use a qt and maybe 8-12 oz. more just to "flush" out the system with all bleeders open.

After the flushing, comes the bleeding. Now I do what Larry suggests, but start with the right rear, then the left rear, then the right front, then the left front.

I'm not made of $$$, but I'm not going to skimp on brake fluid. Pushing a little bit more thru the system in my mind helps to ensure you get a good flush.

Alot of Asian models have proportioning devices and in these cases, you often times use an X-pattern to bleed.
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  #11  
Old 03-07-2003, 08:21 PM
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Thank you very much Mike, I really appreciate your response
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  #12  
Old 03-07-2003, 09:16 PM
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If you are BLEEDING, starting at the furthest point will probably work better. If you are only FLUSHING, starting at the nearest point will flush out with less fluid used.

The ONLY way I can at all buy in on opening all four bleeder screws at the same time is if you are talking about the speedbleeder check valve type screws. These prevent air from returning into the calipers. How in the world could you possibly open all four screws, pressure the system, then get them all closed BEFORE the pressure is gone and air makes it back through the bleeder screws to the calipers? Maybe somebody knows something I don't know. I'm sure there are plenty of people that do, but I wish someone would share this one with me.

Have a great day,
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  #13  
Old 03-08-2003, 01:57 AM
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Great idea...

Thanks Larry and all,

I've always assumed starting at the right rear for any brake job requiring opening the system but the flush vs. bleed just dawned on me. Duh!

Aloha
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  #14  
Old 03-08-2003, 02:29 AM
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Larry:

I fill the tank with 1.5 qts - pressure the system to 15 lbs - open all 4 - one wheel at a time - fluid is now flowing thru all 4 bleeders - not long after I open the left front - it's time to hit the right rear and tighten down.

You gotta move, but it works for me. Like I said above, I learned the concept from a pro brake shop. In their case, they had a real pressure bleeder that held alot of fluid. They would open all 4 and let the fluid flow down into a bucket under each wheel.

Tighest brake pedal I ever had.
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  #15  
Old 03-08-2003, 09:03 AM
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the DIY units work just as well as the commercial units and will easily generate much more than 20 lbs of pressure (that is why a pressure gauge is suggested). the one from motive products is relatively inexpensive though and just about negates the need for making one yourself.

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