R65 Brake lever has no pressure, trying to bleed

[gea4]

I've recently acquired my first motorcycle -- a 1982 BMW R65. Today I decided to do some work on the brakes but have run into problems. I rode it twice the day after getting it back from the mechanic for a tune-up since the bike had been sitting for a long time. He assured me the bike was in good, safe riding condition.

When I got the bike the master cylinder reservoir was cracked and I didn't see any fluid in it from the outside, however I didn't open it up to confirm that until today. As a complete beginner I trusted the mechanic and rode without checking the brake fluid level, unaware of the safety issues.

So today, when I went to add brake fluid and bleed the brakes I noticed the front brake lever had no pressure. Yesterday I was adjusting the handlebar and controls position and unscrewed the union bolt (banjo bolt) to move it a bit. I am not certain but I think this is the point where the brake lever lost pressure, although it could have happened at another time when I didn't notice. Again, I don't know much about what I'm doing, forgive my ignorance, I'm trying to learn!

I followed the brake bleeding procedure in the Clymer manual and consulted http://www.bmwmotorcycletech.info/brakes.htm. There was still very little pressure with my thumb over the hole where I removed the brake hose from the master cylinder. I pumped the lever many times (50+), releasing my thumb pressure a bit to let air bubbles out. Air and brake fluid did come out, but only when the brake lever was pressed almost to the grips. I continued the process and tried bleeding at the bleed valve on the caliper. But, I couldn't get fluid to come out of the valve very far -- only 4 inches into the tube I'd put on the nipple.

What advice do you have? Where did I go wrong and what do I need to go read/learn about before attempting this again? Could it simply be the cracked brake reservoir? I'm skeptical of that because I was able to ride the bike for 50 or so miles with the brakes working, if a bit spongy, with what looked like no fluid in the reservoir.

I'll provide any details or pictures you need to help me with this. I appreciate your feedback!

 

[dieselyoda]

Uhmm, you took it to a mechanic and you have this problem? I guess that's another reason customers don't trust us.

Others will weigh in on any specifics to help you find a solution.

 

[ccolwell]

You need to replace the MC reservoir before riding it again. If it was empty, you're lucky the brakes worked as long as they did; in normal operation the fluid in the reservoir drops as the pads are used. While the pads wear slowly, once there is no more fluid to make up for the wear they will fail as air will enter the sstem every time you pull the lever. And at that point, the MC should be rebuilt as the fluid also functions as lubricant for the seals on the MC piston. If it were me, I'd rebuild or replace the MC.

Having never done the sort of pressure testing you tried, I'll let someone else comment on that. As for bleeding I would do it this way: 1) replace the crush washer(s) at the MC/brake line junction. Probably not necessary but cheap insurance. 2) Bleed the MC at the the MC/brake line junction. Start by remembering that DOT 3/4/5.1 brake fluid is the most effective paint remover so cover every painted surface. I do this with wet towels for the belt and suspenders effect. Loosen the banjo bolt and retighten so that it just seals. Pump the brake lever and gently crack the bolt until fluid weeps out. 3) then bleed at the caliper(s). 4) if it still doesn't work you'll need a syringe to pump fluid in the bleeder valve at the caliper. It that case empty the MC first, pump fluid in from the bottom until the MC is half full, then bleed it from the bottom.

A propos another recent thread: if your fluid is purple or you spilled it on a paint surface and it didn't take the paint off, then the PO may have used DOT 5. In that case, I would rebuild the whole system with new brake line(s) and use DOT 3/4. DOT 5 will cause the brakes to fail eventually.

Lastly, you're a first time rider on a bike with brakes that are 35 years old in both design and age. Give yourself a break (or avoid one) and bring the system up to the best working order you can. New pads, hoses and seals at the least.

 

[gea4]

ccolwell, Thanks for your advice. I ordered a new brake reservoir and hopefully that will solve the problem. I'm using DOT4 and covering nearly the whole front end of the bike in towels, jic. I'll replace lines, fittings, and pads too for good measure. The process I was using to bleed is largely similar to what you suggested, except for trying to pump fluid from the bleed valve, so I'll give that a try. If I can't get any pressure in the brake lever after that I guess I'll take it into a mechanic because I'll be out of my depth at that point.

If anyone has any other suggestions I'm willing to try. Just trying to learn as much as possible.

 

[ccolwell]

ccolwell, Thanks for your advice. I ordered a new brake reservoir and hopefully that will solve the problem. I'm using DOT4 and covering nearly the whole front end of the bike in towels, jic. I'll replace lines, fittings, and pads too for good measure. The process I was using to bleed is largely similar to what you suggested, except for trying to pump fluid from the bleed valve, so I'll give that a try. If I can't get any pressure in the brake lever after that I guess I'll take it into a mechanic because I'll be out of my depth at that point.

If anyone has any other suggestions I'm willing to try. Just trying to learn as much as possible.

Another option that I've used is to get a banjo bolt with a bleeder valve for the MC. I had a Duc with a hydraulic clutch that defied my bleeding attempts (after fitting an accessory slave cylinder) until I fitted one. And, again, since you'll have it all apart and be starting with a dry system, I'd rebuild the calipers (seals only) as well.

 

[SCBuckeye]

When I converted my under-tank M/C to the newer handlebar type, even though brand new, it took MANY pumps to get the M/C to eventually pump and then have pressure to the wheel cylinder. I would keep trying to pump for a while then then go and check below the system to see if you can get any results at the various connections. THEN go ahead and purchase a new M/C or a rebuild kit if one available.

 

[pglaves]

When I converted my under-tank M/C to the newer handlebar type, even though brand new, it took MANY pumps to get the M/C to eventually pump and then have pressure to the wheel cylinder. I would keep trying to pump for a while then then go and check below the system to see if you can get any results at the various connections. THEN go ahead and purchase a new M/C or a rebuild kit if one available.

Once you get the line more or less full, even with a bit of trapped air, that system should gravity bleed itself if you have patience and keep the reservoir full.

 

[shandeland]

Tell us what city and state you live in and someone might be wiling to stop over and give you a hand.
There are a lot of Airheads that like to help follow Airheads fix motorcycles.
Steve