Bleeding ABS Brakes on '91 Accord

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  #1  
Old 06-15-06, 08:01 PM
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Bleeding ABS Brakes on '91 Accord

I've read a number of threads on bleeding brakes and the recommendations are pretty similar to the way that I've done it in the past (gravity, manual, etc.). Since I have a "hung up" caliper, I'm going to replace it and use this opportunity to bleed the brake system. As I was reading through the Haynes manual for this vehicle, I ran across a warning which read in part..."This procedure (bleeding the brakes) should not be undertaken on a vehicle equipped with an Anti-lock Brake System, since special tools are needed to properly bleed the brakes. Take the vehicle to a dealer service department or other repair shop that has the proper tools." My question is, do I need to be concerned about this statement, or is this an overly cautious author? The second question is, if I can do the job myself, is there anything unique about bleeding an ABS equiped brake system versus one that doesn't employ ABS?

Since I can't afford to have the car on stands, I'll be performing the repair by Saturday morning (6/17). So, your timely responses would be greatly appreciated.
Thanks. Rob
 
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  #2  
Old 06-15-06, 08:28 PM
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Don't let the fluid run completely dry in the resorvoir and you will be fine.

Do the normal bleed have some one pump the brake 3-5 times. press hold, crack the bleeder loose when the stream starts to go down tighten it before it gets back in the caliper and then repeat till all air is out. Leave key off and vehicle not running.

If your flushing the whole system start at the passenger side rear, then driver rear and then passenger front, then driver front. I am not quite sure why I have read that you bleed the longest lines first.

Becareful of the ABS speed sensor behind the rotors.

If you get air in the ABS system it could essentially cause the abs to not operate to its full potential. Don't worry about it in my opinion that statement was made back in the day when ABS was considered extremely high tech so they labeled it as needed special attention.

I have done my fair share of old accords I never really pay attention to if they are ABS or not. All that matters is you don't break that speed sensor. If it is full of filings clean the pick up of it off.
 
  #3  
Old 06-15-06, 08:46 PM
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Scalar,

Thanks for the informative post. Just a follow-up though. I read a comment by a technician where he indicated that gravity bleeding does take a little longer to perform and can require a lot of new brake fluid to push out the old dirty fluid, but the risk of doing internal damage to the anti-lock system is greatly reduced. To that end, even though it might be more time consuming, would it be more advisable to use this method?

Also, I've seen recommendations to replace the brake fluid every 30K miles...especially on ABS brake systems. Given the frequency of these changes, what are your thoughts of buying vacuum assisted brake bleeding and flushing equipment to help speed up the process? Any suggestions...that cost-wise would be appropriate for a shade-tree mechanic?

Lastly, how do you clean the ABS pickup...compressed air, soft rag?

Thanks again.

Rob
 
  #4  
Old 06-15-06, 09:08 PM
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Ok if your worried about damaging your abs through bleeding then just don't use your brakes. (joke) The abs is very simple it composes of a few actuators and a pump. during normal braking the actuators allow for normal fluid flow. When the ABS is operated the actuators do stuff and there is a pump that pushes the brakes fluid that is by you feel the pedal pulsate when the abs works, the pump is pushing the fluid against your foot.

So ya bleeding it do it how you please just don't let the brake fluid resorvoir go dry because if air gets in the system it can be hell to get out. You can let it go low and then gently poor fluid in so you minimize old fluid mixing with the old.

I am nut bag with changing brake fluid on my car but I change it only when I have to service the brakes (i.e. change pads calipers etc) A good rule of thumb I go by is once you change the fluid don't take the cap off till your gonna change it again.
If the fluid is getting low you better inspect your pads for wear because thats where the fluid is if it didn't leak out. Low fluid is a sign of needing pads soon. essentially I wouldn't hold 30k miles like the bible, you should be fine with doing it when ever servicing the brakes. Some people have 200k miles and have never changed the fluid. Some manufacturers still don't even have an interval for changing it so thats my 2 cents on when to change the fluid.

Speed bleeding systems basically if your doing brakes every day and are getting paid book time go for it buy them. But if your doing it for yourself and only do brakes once in a great while get a buddy to pump the brake it will save you lots of money and still be a fast way to bleed the brakes.

If the ABS speed sensor has filings on it, it will look like a magnet that has metal filings hanging on it, treat it as so, just brush them off.

Just for my opinion my favorite brake fluid is the vavoline synthetic found at pepboys its the best stuff on the market in my opinion for street cars, just don't buy silicone fluid thats a NO NO
 
  #5  
Old 06-16-06, 06:21 PM
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Scalar,

Thanks for your comments. My dad will be coming by tomorrow to help with the bleeding. So, we'll have some good bonding time. By the way, I've decided to change both calipers out. Buying two loaded ones costs only a little more than buying one stipped down caliper and having to buy the shims and pads.

Final question.. what is the effect to the brake fluid when you open the reservior cap? Seems that based on your answer, you want to keep the cap on until the next bleed. Does it really degrade that much when exposed?

Thanks again for your thorough answers.

Rob
 
  #6  
Old 06-18-06, 06:52 PM
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The end of the story.

I installed the two new loaded calipers yesterday. Started by bleeding the read passenger side first. First did it by gravity. To slow a process. Than tried the pumping method. Faster than gravity, but slower than what I'd experienced when I'd done it before. We thought to do the two new front calipers, since they certainly had air in them. This was the ticket. After evacuating the air out of the two front calipers, we did the passenger side rear caliper. No bubbles....just needed to clear out the old fluid. Next was the drivers side rear caliper. We then double-check the two front calipers. No air. Job done.

When you replace a caliper, is it best to first bleed the new caliper...no matter where it is?

Thanks.

Rob
 
  #7  
Old 06-19-06, 12:43 PM
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I say leave the cap on because it reduces the rate at which moisture gets in the system. Some people take the cap off a lot to check it like sometime every oil change. Also it is recommended that you don't use brake fluid that has been sitting around for a while. Plus if it is full and you compress the calipers the fluid goes all over to. I have a boiling temp tester for brake fluid and I play around with it for the hell of it with fluid sitting around and I have taken the cap off a bottle broke the seal and (tested it) put it back on left it in the garage for a month then checked it and it was 35deg lower than when I first opened it. So I would assume if you keep taking the cap off and checking the fluid, your boiling point would drop pretty quick after a few months. Which kinda defeats the purpose of going to the hassle to flush the entire system.

I usually bleed the lines that had the calipers replaced first. Since they were both in the front it really doesn't matter. I have no reason for order of bleeding. The brakes are set up where the backs are on the same and the front are on the same. You usually want to do the longest line of the set first. I don't think it really matters. You just need to make sure get the air out.
 
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