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Accumulator Replacement

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I am waiting for a new accumulator to arrive from gmpartsdirect.com. Can someone give me a comprehensive set of instructions for removing old and installing new accumulator?<BR>Keep in mind I am not a mechanic.<BR>1989 Coupe<P><BR>Thanks, Don

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The service manual says to pump the brake pedal 25 times. This is with the key OFF, engine not running! The accumulator stores hydraulic fluid, under pressure. The pumping is to remove this stored pressure.<BR>If your accumulator is bad, the pressure will be relieved is maybe 5 pumps. I don't think there is any way of telling from the feel of the pedal when the pressure is gone.<BR>Before unscrewing the accumulator, place some rags or plastic bag to catch any brake fluid. Remember... brake fluid will remove paint! Also clean the base of the accumulator to remove dirt, grease, etc that might contaminate the fluid when the new accumulator is installed. <BR>Unscrew the accumulator. There is a Torx fitting on the top that looks to be about a #40 or 50. I used a oil filter wrench around the body. Give it one or two turns and wait, if there is any remaining pressure, it should leak around the threads, listen for leaking fluid under pressure.<BR>Remove the old accumulator, clean the threaded area with clean rags or paper towels, make certain the gasket area is clean. The new accumulator should come with a new gasket, if it doesn't use the old one after you clean it. If the old one appears to have damage, get a new gasket, either from GM or check with people that make hydraulic hoses, a tractor store, etc. <BR>Screw it in TIGHT. no specs on the torque.<BR>Start the engine, check for leaks, and see if you have brakes. Refill the brake reservoir as required.<BR> <BR>At the same time, unplug and replug the two relays located on the firewall next to the brake master cylinder. This is just to clean the contacts, which after 10+ years can get contaminated. <P>------------------<BR>Barney Eaton Reatta technical advisor for BCA and keeper of the Reatta database.<p>[This message has been edited by Barney Eaton (edited 08-23-2000).]

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DBD,<BR> How did you determine you needed a new accumulator?<BR> After you have A. unscrewed(I got a face full of fluid after pumping 30 or 40 times)it may appear it won't clear obstructions,lines,etc,but it will,just mess w/it.<BR> The time to add fluid is when sysyem is depressurized,only to full mark.If it goes down upon pressurization,don't fill till you have depressurized again.Someone reported over filling will do damage!<BR> I'm not sure but I think there are 3 clues to needing a new accumulator(the manual says to attatch pressure gage W/ GM adapter and time pressure buildup and leakdown).<BR> 1st clue - 5 or 6 or less pumps w/ engine running till one of the lights come on. But this could be wrong if pressure sensor shut pump off prematurly before full pressure was reached??<BR> 2nd clue - A short total time for pump to run from complete de-pressurization to stop. Logic? Pump runs slower when building pressure against accumulator pre load.??<BR> 3rd - Clue-Test # 2- If pedal gets hard in 13 or less pumps means there wasn't much volumn to start with.??<BR>All these theories depend on various conditions of parts i.e.-A pump may be almost worn out,decreasing volumn output,and taking longer to reach max. pressure.<P>Hope you will run tests again when A. is replaced and post!

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Thanks guys for instructions(hope your both guys hehe). Can you tell me if crossbar(dont know if thats what its called) has to be removed? <BR>By the way Wally I felt only 2 pumps for lights to come on may mean need for new accumulator. If not it cant hurt to change a 11 year old part thats so important to the brake system.<P>Thanks,<P><BR>Don<P>

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I am also waiting for a new accumulator from gmpartsdirect.com. I have just posted my brake test results on Wally's post. From all that I have read (and I have been reading all of this, because an instant loss of brakes with no warning scares the **** out of me ) and from comparing my test results with the others I don't think my car has any apparent brake problems(except I have never liked the feel of the pedal from the time I bought it).<P>I bought an accumulator anyway. Why? What I have read leads me to believe the accumulator is a diaphram, which is subject to wear over time, and I now consider it a maintenance item. For $85 w/shipping it is cheap peace of mind as far as I am concerned, I am sick of worrying myself as to whether my brakes are going to be there when I step on them. So, rather than ignore this page I bought the accumulator in hopes it will give me peace of mind(and hopefully a better pedal) I am also going to replace the relays, and keep my current set in the trunk.<P>I was also going to ask for detailed installation instructions. Special thanks to Barney, Wally, and everyone else contributing their time and resources to helping the rest of us stay safe.............Dan tdc@jersey.net

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Barney...the required tool to loosen and tighten the accumulator on my '89 was a 5/16" allen wrench - a perfect fit! Good Luck

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Don,Removed A. w/o removing anything else but may have pulled or pushed a little.At 1st didn't think it would clear hyd. line,etc but kept on and found right position.

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Replaced mine yesterday. No leaks. Part came with new O ring. On 1st observation it seems that brakes have a better feel ( less mushy) then before. Need less foot pressure to apply brakes and they work more smoothly. Also found that removing the 2 nuts on right side of brace makes installation alot easier. Will post my new test results soon.<P>Don

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Replaced my accumulator today thanks to the tips in this discussion. I have been searching for a while to find a definitive answer besides "rip everything out and replace it to be safe." I ordered the accumulator from my local Pontiac/Buick dealer and he had it the next day. There were apparently a bunch of them in the Fort Worth warehouse. He gave it to me for $130 instead of $150 because I said I saw it on the net for that price. Anyway, after reading the instructions I grabbed my torx set and had the job done in 15 minutes including pumping the system down twice and a test-drive. The ABS now acts like an ABS. I can feel the pedal movement and the warning lights are no longer on at all. The system working sounds a bit like a ratchet tightening down in a high-speed panic stop but it tracks true and smoothly through it.<P>Thanks to all who helped with this. <P>Chief<BR>

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Could you please post the part number for the accumulator for a '90 coupe? When I go to gmpartsdirect.com, they don't go back to a 1990 model anything. Looks like you need the part number to order anything for an older car. <P>If you have any other part numbers for other brake-related parts, they would be appreciated also. <P>After reading everyone else's results, I think replacing mine is a good idea. <P>Thanks in advance.

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I found the part numbers by doing a search of previous messages. <P>Here they are for those of you wanting to replace your accumulator and pressure switch. <P>Accumulator P/N 25528382<BR>Pressure Switch P/N 25533700<P>Note: The pressure switch number was posted with a typo error in an earlier message as 25573700. This is incorrect. <P>The best price I found was at gmpartsdirect.com. The price posted at partsgm.com was about 20-25% higher. <P>I plan to replace both parts as soon as they arrive, then have the system flushed at a local shop. Will let you know what results I get.

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