Hydraulic Clutch Bleeding

[dbvolfan]

So I followed Warchild's instructions from FJRtech (excellent BTW!). Everything seemed to go OK (old fluid flushed out and I did at least 15 fill/pump/refill iterations and everything looked good and appears to be working fine after a 3 mile trial run.

I used a mity vac. For those of you who used that did you get a 'solid' stream of fluid from the bleed nipple or was it mixed with air/fluid? I used the std hose and finally the small one that was airtight. Each time I got fluid and air....never a full solid stream. I kept the resavoirr full so I dont think any air got in to the system. I pumped at least 16 oz. through this thing and it was flowing just fine but it was never all fluid. Is this normal? Could I be overlooking something? Any help would be appreciated before I tackle the brakes and my other bike.

Thanks!

 

[madmike2]

You are seeing air that seeps around the nipple (it looks almost "foamy"). If you will pump a "very little" vacuum or even no vacuum, then bleed by squeezing the handle, you will get a solid stream.

Its happened to all of us.

 

[dbvolfan]

Thanks for the reply...I thought that might be it so I put the smaller drain hose on it that was sooo tight I darn near stripped the skin off my knuckles sliding it over the nipple. So if I was getting some air in around the nipple/hose could that introduce some air into the system?

 

[jestal]

Thanks for the reply...I thought that might be it so I put the smaller drain hose on it that was sooo tight I darn near stripped the skin off my knuckles sliding it over the nipple. So if I was getting some air in around the nipple/hose could that introduce some air into the system?

The air mentioned is leaking past the threads of the bleeder valve, not between the hose and the nipple. When you loosen the bleeder valve the threads are not air tight so when vacuum is applied it pulls air past the thread as well as fluid from the hydraulic system.

Even if the hose to nipple connection was leaking you won't get any air in the system as long as there is sufficient vacuum to keep pulling some fluid from the hydraulic system.

If the clutch feels solid and works well there likely isn't any air in it to worry about. A spongy clutch lever would be a sign of air in the system.

Next time you go to bleed brakes or the clutch take the bleeder valve out and wrap several turns of teflon tape around the threads and then reinstall it. The teflon tape will help seal the threads a bit and prevent air from leaking past when the vacuum is applied.

 

[staledonut]

OOOO! This is so good to know as I'm very soon going to obtain a Mity Vac to replace my antiquated hose and jar setup and bleed all the hydraulic circuits on my 05. I'm sure I would have also been fooled by air sneaking past the threads eventually becoming violently distraught over the matter.

Thanks Madmike2, Jestal, and most of all, Dbvolfan.

 

[tyronewildman]

<SNIP>I used a mity vac. For those of you who used that did you get a 'solid' stream of fluid from the bleed nipple or was it mixed with air/fluid? <SNIP>

The tape on the threads works O K to make the threads air tite but an easaier way is to make a "Tinkers Dam" around the threads. I take a toothpick and apply a small amount of grease/vasoline between the threads of the nipple and the caliper (or whatever the nipple is screwed into. When the nipple is unscewed to allow bleeding, the grease flows around the threads and no air bubbles. It's an easy cleanup also. You do know what a "Tinkers Dam" is, don't you? Later,,, De

 

[Geezer]

The 'tinker's dam' sounds like a better idea than using any kind of sealant on the threads of the nipple, but either way I would be careful about contaminating the hydraulic fluid in the system. Brake fluid is pretty nasty stuff and will disolve your paint so I would be concerned about it disolving teflon tape or other thread sealant or even the grease you might use to make the dam.

 

[HondaCBX6]

I use grease around the nipple. It works great. You do not need to open the nipple very far to get your lines to bleed. With a small amount of grease around the threads there is no air leak. The grease is too heavy to be pulled through the threads so there is no worry about contamination. I've been doing this for years with no problems. Air can get through the smallest of gaps. But the grease is too thick to travel past the threads. Nothing to worry about.

John

 

[dbvolfan]

Thanks for the feedback....never thought about the grease, so I will have to try that next time. No ill effects from the change this time so I assume there was no air left in the system.