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Discussion Starter #1
Just replaced the rear master cylinder on my '99. I'm trying to bleed the brakes using a vacuum pump and can't get fluid to flow.

On my last trip my rear brake lost all pressure. There was fluid on and around the master cylinder. I assumed it was leaking from the cylinder so bought a used replacement. I've tried bleeding from both the ABS unit and the wheel cylinder. I've gotten a very small amount of dark dirty fluid, but it won't flow from either port. The vacuum pump is holding pressure. Could the ABS unit be plugged?
 

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Just replaced the rear master cylinder on my '99. I'm trying to bleed the brakes using a vacuum pump and can't get fluid to flow.

On my last trip my rear brake lost all pressure. There was fluid on and around the master cylinder. I assumed it was leaking from the cylinder so bought a used replacement. I've tried bleeding from both the ABS unit and the wheel cylinder. I've gotten a very small amount of dark dirty fluid, but it won't flow from either port. The vacuum pump is holding pressure. Could the ABS unit be plugged?
On the 99, there should be a clear single path from the master cylinder to the rear caliper via the ABS unit as that year has ABS II and not the 2 circuit I-ABS.

I would be surprised if the master cylinder was the cause of the leak and not the brake line from it to the ABS but it could be.

If the vacuum won't pull the fluid through, then maybe you have the supply from the reservoir twisted or something blocked.

Have you tried the manual method. If you have fluid in the reservoir and the line to the master cylinder is fill, you should see a small spurt of fluid push back into the reservoir when the pedal is depressed. Check the supply line for kinks and make sure you don't have a leak on the line from the MC to the ABS.

Loosen the line at the MC and see if you can get fluid to leak out when you press the pedal and as always, keep that stuff off the painted surfaces.
 

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Discussion Starter #3
OK - I've still got vacuum with the pump on the ABS unit port and the banjo bolt on the master cylinder removed so it looks like there is blockage either in the ABS unit or the line to the master cylinder.

How do I get to the ABS-MC line? I can't even see it once it disappears into the right side. I assume it attaches on the bottom of the ABS unit. Can I get to it if I remove the battery?
 

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Found it - checked a parts diagram just after I posted.
The line is plugged. Looks like it won't be a winter-long project after all.
 

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OK - I've still got vacuum with the pump on the ABS unit port and the banjo bolt on the master cylinder removed so it looks like there is blockage either in the ABS unit or the line to the master cylinder.

How do I get to the ABS-MC line? I can't even see it once it disappears into the right side. I assume it attaches on the bottom of the ABS unit. Can I get to it if I remove the battery?
The tupperware has to come off to even see it properly. It is tucked up under the right side.

First i need to ask you which bleeder port you are connected to on the ABS unit. The rear port on the top of the unit is for the front brakes and the front port is for the rear brakes. Make sure you are applying vacuum to the correct port.

In answer to your question on where the MC line connects, there is a coupler attached to a metal plate just up under the side where it goes under stuff. You can see it from under the seat if you look just right. I have it circled in this picture so you can find the other end where the banjo bolt is. It is a metal line from there to the ABS.
 

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Found it - checked a parts diagram just after I posted.
The line is plugged. Looks like it won't be a winter-long project after all.
Erik, have you changed to Spieglers? If not please do.

Robert
 

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Attached picture with location of the rear MC link to the ABS. Looking down under the seat in front of the battery.
 

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the hose from the reservoir to the master cyl behind the side plate must be installed correctly or you will squash the feed line preventing the fluid to flow. you should be able to bleed through the rear caliper engine off
 

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Discussion Starter #9
Thanks for all the advice.

I do have most of the plastic off. I didn’t see the end of the hose because until I looked at the parts diagram I didn’t know what I was looking for. Good time to flush all the fluids. From what I’ve purged already, it looks like it’s long overdue.

Is there a trick to running the line to the reservoir without pinching it?

No Robert, don’t have Spiegler lines yet. They are on the project list. I’ve had this beast a little less than a year and am still learning all about it.
 

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Thanks for all the advice.

I do have most of the plastic off. I didn’t see the end of the hose because until I looked at the parts diagram I didn’t know what I was looking for. Good time to flush all the fluids. From what I’ve purged already, it looks like it’s long overdue.

Is there a trick to running the line to the reservoir without pinching it?

No Robert, don’t have Spiegler lines yet. They are on the project list. I’ve had this beast a little less than a year and am still learning all about it.

Erik, if your lines are original they are 16 plus years old! That is a failure ready to happen and unsafe.

Robert
 
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Thanks for all the advice.

I do have most of the plastic off. I didn’t see the end of the hose because until I looked at the parts diagram I didn’t know what I was looking for. Good time to flush all the fluids. From what I’ve purged already, it looks like it’s long overdue.

Is there a trick to running the line to the reservoir without pinching it?

No Robert, don’t have Spiegler lines yet. They are on the project list. I’ve had this beast a little less than a year and am still learning all about it.
Just did a quick calc of the ABS rubber lines only form Max BMW. Without any tax or shipping washers etc, the 5 rubber brake lines come to just under $400 so at $245.95 ( price off the Spiegler site), they are certainly the deal to pursue. That one line from the MC to the ABS blew for me and I bought the BMW line for $57. After the second line blew, I went for the entire set out of safety concerns of another blow out on the front as both rear had now gone on mine within a month.

Just remember, they go without any warning and yours are older than mine were so push that one item to the top of your project list as soon as you can do it. Just about anything else can wait.

Once you get those lines bled, give that new MC a good stand on the pedal test and make sure that it wasn't the MC line that was leaking and was the MC as you suspected. Since it is ABS II, the ignition doesn't need to be on for that test.

Good luck on the bleeding.
 

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Does the Spiegler kit includes ALL the flex lines I'd need?
The kit includes all 6 flexible brake lines and crush washers including the junction block for the front. My kit included a couple extra crush washers. I think these are aluminum washers ( by the color) and I prefer the copper ones from BMW but they did the job.

Make sure you follow the torque specifications for those washers. Too tight and they will split. There were other recent threads where someone mentioned you could get colors for the same $$ as the no color lines from spiegler but I don't remember what site that was.

The kit does not include the clutch line and I wish it did. The 3 pieces for that are $463.53 from BMW. I think I will be taking them off and going to a local shop to see about a SS rebuild. Spiegler doesn't make those. They are not as high pressure and less of a major safety issue but still 14 years old in my case.


https://spieglerusa.com/brakes/brake-lines-accessories-tools/cycle-brake-line-kits/make/bmw/model/k-1200-lt/year/1999.html
 

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Discussion Starter #14
OK, I changed the priorities on my project list. I canceled my order for the ABS to master cylinder line & ordered a set of Spiegler lines.

I've got a BSA Thunderbolt project that just got pushed further back on the list.

I might be looking for some more help once the lines arrive.
 

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OK, I changed the priorities on my project list. I canceled my order for the ABS to master cylinder line & ordered a set of Spiegler lines.

I've got a BSA Thunderbolt project that just got pushed further back on the list.

I might be looking for some more help once the lines arrive.
If you actually live in Newnan, I may be close enough to render assistance if you need it however, I will not be available all next week. I did mine manually and had my girl friend work the pedals/leavers while I worked the catch bottle and bleeder valves.
 

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Discussion Starter #17
bmwcool - Thanks very much for the offer but my parts came in on a rainy day, I got impatient and installed the lines. Easy job- Got the brakes bled and all the plastic back on. The sun is finally coming out, gotta go try it out. Looks like you are only about an hour from the mountains. We'll have to get together and go ride one day.

Also, on my ABS unit the front port is for the front brakes, rear for the rear. My Clymer manual shows it that way too. Odd

If you actually live in Newnan, I may be close enough to render assistance if you need it.
First i need to ask you which bleeder port you are connected to on the ABS unit. The rear port on the top of the unit is for the front brakes and the front port is for the rear brakes. Make sure you are applying vacuum to the correct port.
 

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Glad you changed your original rubber brake lines for the stainless braided type.

When my 1999 R1100RT brake line failed (rear line) I was sitting in my driveway and stepped on the brake while I started the engine in neutral. The rear line split and shot brake fluid clear across the driveway (20'). I can imagine what it would have felt like if I had lost a brake line on the highway or at a traffic light.

I recommend that ANYONE who is still using OEM rubber brake lines on these fine old bikes to make changing the brake lines to modern stainless braided lines your top priority, any brand. I had a complete set custom made by a source in Canada for less than $100.00. What a difference in stopping power!
 
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Also, on my ABS unit the front port is for the front brakes, rear for the rear. My Clymer manual shows it that way too. Odd
I apologize for relaying incorrect information. I looked at my Clymer manual to see which port was front and rear before I wrote that and when I looked at the picture, I thought the bleed nipples on top were inside the frame and I was looking at it from the right hand side of the bike. I just went outside to verify my mistake and they sit on the outside of the frame so that makes them exactly as you say, front is front and rear is rear.

Glad you got them changed out in spite of my dyslexic instructions. :nerd:
 

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I apologize for relaying incorrect information. I looked at my Clymer manual to see which port was front and rear before I wrote that and when I looked at the picture, I thought the bleed nipples on top were inside the frame and I was looking at it from the right hand side of the bike. I just went outside to verify my mistake and they sit on the outside of the frame so that makes them exactly as you say, front is front and rear is rear.

Glad you got them changed out in spite of my dyslexic instructions. :nerd:
Not a problem. I thought I'd heard that someplace else too. Figured mine must be the odd one. Never know what you will find with 16yr of DIY maintenance.
 
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