Occasional Brake Fluid leak at Right Front Caliper

[Dr Klawn]

I'm looking for some help on this leak. After replacing my front master cyliner at the end of August, I bled the front brakes and all was fine. On our recent two week vacation, I noticed (on the second to last day out) that some fluid had been seeping from the bleed nipple on the right front caliper. The day before had been some hard riding on CA Rte 49 / 89 then over Mt. Lassen. When I pulled off the protective rubber cap, some fluid came out, as it had been sitting there. I could get none to come out when I squeezed the brake lever, then or now. Could I have overtightened this nipple or could it be something else?

 

Thanks for the help!

[Larsen]

A couple of things could have caused this. Originally the right front caliper on most R1100 Series Bikes had a BMW Special Bleed point.

 

When this was removed it might have been replaced with a matching bleed nipple like the left front and rear calipers have, or someone might have put a speed bleeder in that position.

 

It could be just a bit of dirt or something between the nipple and the seat. Whenever I've had a slight leakage as you've seen the bleed nipple might have to be tightened just a very very little to seat the nipple. You don't want to tighten too much as the nipple could snap off, especially if it was a speed bleeder. It's very rare that overtightening could cause a leak but I've been called to remove many broken bleed nipples that had been broken off over the years.

[Ron Jarvis]

Like you, I was not aware that the bleeder on the right front was different from the left (or same as the rear). I just did a master cylinder re-build and bled the brakes and really had to crank one side down hard to keep it from leaking. Anyway, I'd like to know if you are using Speed Bleeders or standard BMW bleed valves? Thanks. Ron

[Dr Klawn]

A couple of things could have caused this. Originally the right front caliper on most R1100 Series Bikes had a BMW Special Bleed point.

 

When this was removed it might have been replaced with a matching bleed nipple like the left front and rear calipers have, or someone might have put a speed bleeder in that position.

 

It could be just a bit of dirt or something between the nipple and the seat. Whenever I've had a slight leakage as you've seen the bleed nipple might have to be tightened just a very very little to seat the nipple. You don't want to tighten too much as the nipple could snap off, especially if it was a speed bleeder. It's very rare that overtightening could cause a leak but I've been called to remove many broken bleed nipples that had been broken off over the years.

 

I know that some bikes came with a "grub screw" on the right side, I'm not sure if mine did as I bought it used. The bleeder matches the left side (no speed bleeders). It is tightened down as far as I dare... What I did notice, when I looked at it again this morning, was that the rubber base washer(?) that connects to the protective cap seems slightly compressed into the hole on the caliper, compared to the left side.

[Larsen]

The rubber cap should not affect wether or not the bleeder nipple leaks. It is there to keep dirt out. Most cars and trucks that I've worked on have no protective cap after a few years. Take the cap off and hold maximum braking pressure for a minute. If it no longer leaks I'd not worry about it.

Good luck,

[Larsen]

On my 1st R1100RT I installed Speed Bleeders in the front just to see how they'd work out as I have them installed on some of my cars and truck to make it faster and easier to bleed the bakes by myself without anyone elses help.

 

On my 2nd R110RT, my K Bikes, and my son's K1200RS I just reach down and bleed the brakes while holding pressure with one hand. If you have arms long enough to reach I don't see the need for the Speed Bleeders.

[KMG_365]

. . . the rubber base washer(?) that connects to the protective cap seems slightly compressed into the hole on the caliper, compared to the left side.

I would just make sure that that little "keeper" ring for the dust cap didn't get pinched in the threads keeping the screw from seating fully. Otherwise, as noted above.

[Dr Klawn]

[quote I would just make sure that that little "keeper" ring for the dust cap didn't get pinched in the threads keeping the screw from seating fully. Otherwise, as noted above.

 

I think that may be the problem. I assume that I'll need to loosen or remove(?) the bleeder to fix the "keeper" then rebleed the caliper?

[KMG_365]

I think that may be the problem. I assume that I'll need to loosen or remove(?) the bleeder to fix the "keeper" then rebleed the caliper?

 

Don't know how anal-retentive you want to be about it, but the quick fix would be:

 

1) leave the dust cap on (to prevent too much flow from the reservoir above)

 

2) loosen the bleed screw just enough to free up the keeper and make sure it's not binding

 

3) tighten the bleed screw back down snugly (without stripping it)

 

4) thoroughly clean the caliper of brake fluid

 

. . . and if you want to quickly tell if the fix took:

 

5) NOW remove the dust cap and get a Q-tip (or other cotton swab)

 

6) remove the bulk of the cotton on the end (by force if necessary! )

 

7) shove it down the central bore to get all the brake fluid remaining in the bleed screw out

 

8) clean and replace the dust cap (with the keeper now NOT caught in the threads! )

 

9) re-clean the caliper of all brake fluid residue with brake cleaner and rags (protect your paint from BF! )

 

(Sometimes the brake fluid remaining in the central bore leaches out with the heat [over time] and makes it look like the bleed screw is leaking when it really isn't.)

 

10) Go and ride the piss out of it on a mountain road and do lots of hard braking (get the brakes hot)

 

11) stop and check for leaks

 

12) pat yourself on the back or go to your dealer for a new bleed screw!

 

 

This would be the easiest thing to try before you tear into it more radically. If you don't remove the bleed screw all the way, some fluid may leak out from gravity pulling down on the fluid in the lines, but no air should enter the system requiring a bleed (it's still going the right way after all! )

 

Good luck and post back of your success!