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Discussion Starter #1 (Edited)
Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Hopefully John Z., Mark, or another of you "wisemen" on here can help me out.

I just installed a used brake pump that i finally found for my 04LT. The old one had 48k on it and unfortunately...I never flushed it with new fluid...didn't know it was reccomended annual maint...oh well. The install of the "new" one went very well...easier than I expected. Thanks to ColoradoGrant for his help and encouragement as he just did the same "ordeal". I "backfilled" the wheel circuits and bled properly following the BMW shop manual. I had plenty of fluid coming out of all control circuit bleed points. Everything seemed to go too easy....lol....I knew it was too good to be true!!

WELL....when I had the battery back in and turned on to bleed the wheel circuits ...I got a constant fast flashing "brake failure" light, a solid warning triangle light and the pump would "sing" loudly all the time. The front brakes work and bled normally at the front calipers. The rear brake did not have any fluid being pumped out at the caliper when trying to bleed and the brake pedal felt soft and did not seem to offer any resistance the further it was depressed. I am going to do another rear control circuit bleed...I hope its just air in there somewhere and not that the pump is bad.

Any advice or comments are greatly appreciated.

Thanks,
Steve
 

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Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Well it does sound like you picked up a bad one. No amount of bleeding will fix that. Wish I had better news but based on the symptoms that is my call. Now maybe if you wanted to get brave and swap out the brains from your old unit to the new it might fix it but I don't remember the exact failure of your old one. If it had a bad front circuit then you might be able to use the rear stuff. but it is a crap shoot until we have a chance to open several of thes up to experiment. By the way I will take all old dead ABS units I can get my hands on just for this purpose.
 

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Discussion Starter #3
Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Lol....figures... The guy who sold it on Ebay had a 30 day return guarantee right in the ad. I'm so glad he did because when the pump arrived I called him immediately because of the box/packing job he did. It was in a thin walled carboard box that did not have all the edges taped. Two edges on opposite corners were completely seperated letting the packing peanuts he put in the box fall out....there was still about a half box full in there. On top of that he did not have the pump in any kind of bag...it was completely exposed to the packing peanuts and unfortunately whatever "dirt" found its way into the box from the ripped open corners. I couldn't believe it....i was flipping out. I called him to vent and explain to him in the future he may want to pack expensive and "dirt sensitive" parts like this pump better!!

Well...looks like I'll be contacting him to discuss the return. I'll still try another bleed first while still in the bike. If it doesn't get it working...I am thinking I may bite the bullet and buy a new pump now that I know the install is not that big of a job...just a little time consuming.

Steve
 

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Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

jzeiler said:
Well it does sound like you picked up a bad one. No amount of bleeding will fix that. Wish I had better news but based on the symptoms that is my call. Now maybe if you wanted to get brave and swap out the brains from your old unit to the new it might fix it but I don't remember the exact failure of your old one. If it had a bad front circuit then you might be able to use the rear stuff. but it is a crap shoot until we have a chance to open several of thes up to experiment. By the way I will take all old dead ABS units I can get my hands on just for this purpose.
I took apart a "failed" ABS unit for grins and posted some pics of the components a while back. I couldn't find anything wrong with the mechanical side of things but I decided to throw the parts in the metal recycle bin rather than reassemble it. What I found suggested that if there was a failed component, it was on the circuit board. I still have that "brain" because it has a different recycle path and it didn't get dumped with the other parts.
If you want the brain for experimentation, pm me a shipping address and I'll send it along. IIRC it is from a 2000.
 

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Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

loser said:
On top of that he did not have the pump in any kind of bag...it was completely exposed to the packing peanuts and unfortunately whatever "dirt" found its way into the box from the ripped open corners.
Steve
Steve,

If the line ports were open and debris got in there is a possibility it could cause this. Where each line enters the ABS unit proper there is a fitting (under the rubber cover). Try removing the lines there and unscrew these fittings as they have a large filter screen built into them that may have been clogged. The ones by the big black domes are the input and the the ones at the end are the output. It is worth a try. But don't risk being able to return the unit as this may not pan out.
 

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Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Is it possible your ABS relay is stuck, making the unit run constantly? Did the old unit act the same? Just thinking out loud. I imagine John is correct about your pump.
 

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Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Only the ABS II use a relay to operate the motor int the ABS module. The integral are controlled by brake switch and pressure input in the control circuit. If a servo pump operates all the time (barring any external input) then it is usually a failed power tab transistor (shorted) on the brain board.
 

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Discussion Starter #8
Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Thanks for the comments guys.

John: I looked very closely in the "line junctions" before installing the pump. I did not notice anything but obviously I could not see small dirt particles or anything that may have gotten in very deep. I will look into trying to take out and clean the screens. The brake pedal def feels soft so I am hoping it was air in the line or possibly a leak. I did not see any leaks and will try one more bleed tonight.

I have shared a few emails with the seller of the pump. He bought two wrecked bikes to "build into" one. The pump I bought is from an 04 that had 7000 miles. I'm wondering if that may be bad as it was probably never flushed and may have "old brake fluid" issues like my original had. I am going to talk to him tonight as he said he may have a few things for me to check based upon his experience.

My original pump would not build enough pressure. It would provide a little (very minimal) braking/stopping but not full power. IF i would really squeeze or stomp on the brakes the pump would kick in and give me full braking force in the front but still only partial in the rear. I would then get the flashing brake light and solid warning triangle. PLUS....if I kept riding the bike after that happened....a few minutes (or brake applications) later....I would lose all braking power....not good. I tried several flushes on this pump before removing but did not do the COMPLETE refill and bleed proccess that includes all three bleed points for the control circuits. I may put my orig pump back in and try a "full factory" flush.

Steve
 

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Discussion Starter #9
Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

One more thing... The front brake works normally. The rear brake does not work at all. The rear wheel spins freely. When I crack the bleeders on the rear caliper I cannot get any fluid out. Because the front brake works normally...i am assuming it is the rear servo/motor that is constantly whining but if so...why wouldn't the caliper be clamping the brake pads on the rotor and why wouldn't i be getting tons of fluid from the bleed nipples when opened?? Hmm.....
 

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Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

There is a big difference between 48K and 7K if the brake fluid has not been changed?

Unfortunately, i cannot offer any help with ABS problems.

Is there a way to make temporary connections so that the ABS's connections for the front servo can be routed to the rear servo--rear connections routed to the front servo?

Doing that may indicate where your problem is?

Bob
 

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Discussion Starter #11
Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Regarding 7K versus 48K....I was thinking that if the pump with 7K was not in service or out of the bike (2004) model for several years, the brake fluid and/or pump interior (seals, o rings, etc) may have been exposed to moisture and/or gunk for a long period possibly causing some issues?? Or...even if the pump was in the bike until recently...doesn't the bmw recommended service call for annual fluid change...regardless of miles?? It seems to me the exposure time to moisture (years in brake system on bike) would be more critical than the miles ridden? Or..maybe not....

I dont think its an ABS problem but just a bad brake pump. Are you suggesting swapping brake lines front to rear? The steel lines that connect to the pump are cut and bent to a pretty exact length to mate with the proper ports on the pump. I would be worried about cracking or crimping a line. Plus..it sure looks like the problem is the rear brake side of the pump...the servo motor runs but is not building pressure...not pushing the pads out of the calipers or fluid out the bleed nipples when I open them???

Steve
 

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Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Don't try to swap the lines. I would disconnect at the ABS and try pushing fluid up from the rear caliper to make sure the lines are not blocked. Did you try looking at the screens on the fittings?
 

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Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Electrical connections.
Bob
 

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Discussion Starter #14
Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

I didn't have much time to look at last night...I will this weekend though. I did push on and "check" the main plug into pump and many other wires and connectors in the area and at the abs sensors. No change.

As John said earlier...probably electronic "brain" short or problem...BUT...why would I not be getting fluid from the caliper bleed nipples when I open...if in fact the "whining" I hear all the time is the "pump motor"? Could it be a big air bubble trapped right at the pump diaphram or whatever actually moves to pump fluid in there? When I back filled the rear caliper, pump chamber and into reservoir...it seemed to fill fine. I did it twice to be sure.

Like I said earlier...the front circuit works fine...fluid is pumped out "a hell'n" when I open the bleeders on the front calipers.

John....I will look at the connector screens this weekend.
 

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Discussion Starter #15
Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Well...after working more this weekend on the "used" pump now in my bike...still no change. I refilled and flushed again and am sure that I have no air in the pump. The front brake works fine. Its just still the rear that is not working. It has a little "residual" braking but no power braking...even though the brake motor is running constantly. What I dont get is if the pump is "running" constantly...why I do not get fluid pumping out at the caliper bleed nipple. I am confident that the lines are clear since when I backfilled the pump and reservoir through the caliper that it filled easily with no apparant resistance/resrtictions.

jzeiler said:
Steve,

If the line ports were open and debris got in there is a possibility it could cause this. Where each line enters the ABS unit proper there is a fitting (under the rubber cover). Try removing the lines there and unscrew these fittings as they have a large filter screen built into them that may have been clogged. The ones by the big black domes are the input and the the ones at the end are the output. It is worth a try. But don't risk being able to return the unit as this may not pan out.

I looked at my old pump a bit. I took out two of the four fittings where the brake lines attach to the pump. These are long "stem like" inserts that have two o rings, a few small passage holes and a very fine screen on the end. The screen does not look to be removeable as the plastic housing it is around is molded/crimped into the end of this "stem". BUT....the one screen was very dirty AND...on the end of the "stems" closest to the pump exterior where the brake lines attach, there was some "thick and gooey" stuff that looked like congealed brake fluid. I am thinking I may try taking apart the pump as far as possible for a "weekend wannabe mechanic" to do and try cleaning thouroughly. Maybe I'll get lucky and get it working again?

If anyone has any experience or suggestions with cleaning brake pumps regarding what to use or not use as cleaners....please chime in. I dont want to risk the pump internals with anything too strong but then again it would only be exposed to them for a short time. The chemist in the Lab where I work thought either a 70% isopropol alcohol or maybe a better/safer bet would be to heat up clean brake fluid and use it to keep flushing.

Steve
 

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Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

loser said:
My original pump would not build enough pressure. It would provide a little (very minimal) braking/stopping but not full power. IF i would really squeeze or stomp on the brakes the pump would kick in and give me full braking force in the front but still only partial in the rear. I would then get the flashing brake light and solid warning triangle. PLUS....if I kept riding the bike after that happened....a few minutes (or brake applications) later....I would lose all braking power....not good. I tried several flushes on this pump before removing but did not do the COMPLETE refill and bleed process that includes all three bleed points for the control circuits. I may put my orig pump back in and try a "full factory" flush.

Steve
Maybe you are looking at this the wrong way. You started with an issue and decided the pump was bad, so you got a used one and still have a brake issue.
Are the symptoms similar with the old and "new" pump?
Is it possible that the real issue is with your lines, or the electrical? Have you checked for cracks or bends in the lines...? Old lines can swell on the inside and that would cause a blockage you cannot see.
Maybe try to take a different view by stepping back a little in your troubleshooting effort so you can see the whole picture instead of focusing on the pump (that may or may not be good/bad). JM2CW.
 

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Discussion Starter #17 (Edited)
Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Nope...def two diff issues/doing different things from my original pump and the "new used" one. Plus...I had the dealer do a pressure check diagnostic test on my original..."pump is not building and holding pressure" was there finding. Thats when I found out that they do not rebuild these pumps and was quoted the absurd part price of $2468!!

If you read my posts...I state that the pump back fills from the calipers to the pump and ultimately to the fluid reservoirs just fine, which to me implies absolutely no blockages or leaks in the lines anywhere.Plus...I have done this twice and also bled the pump with what appears to me to be PERFECT PER THE MANUAL results. I'm 97% sold its the pump. I wont rule anything out though.

Right now I'm pretty sure I'll be sending the used pump back to the seller for a refund and trying to clean my orig and install just for shits n giggles to see what happens. I'm just glad I have a couple of "primitive" HD's to ride while trying to fix the LT......just had to throw that in...lol...I do love the LT's ride but give me a HD anyday for simplicity and ease of doing routine maintenance/repairs and as I'm learning...the cost involved to do them....just my $0.02.

Steve
 

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Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Just had my pump go bad using front brake,tried to clean and replace fluid N G,same result.
$2400.00 for new one,this machine is one big money pit,almost as bad as a boat.
 

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Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

Just because the pump is "whining" does not mean it will move fluid. Could have a sheared shaft internally. I Think it is time to give up on this one unit and send it back.
 

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Discussion Starter #20 (Edited)
Re: Installed a "new" (used) brake pump....HELP...pump "singing" all the time, no rears..

John....Yeah...I agree. I will take it out and send back. Just frustrating because I finally found a used pump and the install/bleed went smooth....oh well. Like i said above...I am gonna try to disassemble my old one a bit to clean and see if I get lucky and get it working. I have never seen the type of 5 point star "torx" bolts that are used on this pump. I'm hoping to be able to remove them with a small vice grip locked onto the head and break em loose but if not....will i be able to find sockets of that style or is it some BMW unique style?


boxer259 said:
Just had my pump go bad using front brake,tried to clean and replace fluid N G,same result.
$2400.00 for new one,this machine is one big money pit,almost as bad as a boat.
I feel your pain. My comments a few posts above were not a "slam" on the LT or BMW. Like I said....I love the ride. I am a Harley guy who got turned onto the LT 5 tears ago by my neighbor and openly admit it is an awesome ride. BUT...to me just seems a bit more "involved" as far as recommended routine maint. and potential problems. My current brake pump prob may be mostly due to my never reading the manual and following the recommended flushes...live and learn. Maybe I should look at it from this perspective...An LT of comparable age and mileage is about ~3-4k less than an HD Ultra....so I'm that farther ahead to start. If I wind up buying a new brake pump I'm just kind of getting back to "even" if I would have bought another Ultra insead of the LT.

Steve
 
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