Brake and clutch bleeding

[M61A1MECH]

There continues to be many posts about folks having trouble getting the air out brake lines and the clutch line.

The clutch is much harder in my opinion, but both systems can be painful at times.

 

I was listening to "Car Talk" this weekend, must have been a rerun because Tommy (God rest his soul) was on the show and he died over a year ago.

Anyways, a caller was having trouble bleeding the clutch on her car after changing the master cylinder and slave piston. After the usual banter back and forth, Ray offered an idea that he says they use in their shop. Get a large syringe and fit it with rubber tubing that will fit securely on the bleeder. Fill the syringe with brake fluid and open the bleeder and depress the clutch, with the help of an assistant. Slowly depress the plunger on the syringe and force brake fluid back up into the system, that will push out any air and it should bubble out in the master cylinder reservoir.

 

I had not heard that idea before, sounds like it could work. On the bikes you would have to be very careful not to push so hard as to squirt brake fluid out of the reservoir.

Anyone ever tried something like this? Did it work?

 

Maybe something to offer to the next member that succumbs to the dreaded "Clutch will not bleed" syndrome.

[djh3]

Might be worth a try Steve, if someone just cant get a good feel. I would say maybe just enough fluid in reservoir to cover bottom and you should be OK. So potentially you would need 2 syringes. One for the new fluid your pushing in, and one to empty the reservoir.

[ToyOdie]

I found that when bleeding the clutch or brakes that had an empty reservoir, I needed to tap on the banjo fitting at the reservoir. As I did the air would slowly move up the line and come out as very small bubbles. It takes awhile to get them all out. First cover any painted surface that might get brake fluid on it. Fill the reservoir and close the bleeder. Pump the lever only far enough to get the bubbles to come out. PUMP VERY SLOWLY. Tap on the banjo fitting and keep going. Once the bubbles stop, bleed them at the bleeder normally. You might need to repeat this procedure more than once to get all the air out. I also put Speed Bleeders on all my brakes and clutch to make the job easier.

[Marcarl]

I would say that depressing any cylinder would seal the push side, and no fluid would be able to come to the reservoir. I might not be all that smart though, so better minds can enlighten me. Seems that the whole idea is for the master to push fluid down the pipe, and that can only happen if the pipe is sealed at the time of use. I think the master needs to be in the rest position for anything like this to work.

[M61A1MECH]

I would say that depressing any cylinder would seal the push side, and no fluid would be able to come to the reservoir. I might not be all that smart though, so better minds can enlighten me. Seems that the whole idea is for the master to push fluid down the pipe, and that can only happen if the pipe is sealed at the time of use. I think the master needs to be in the rest position for anything like this to work.

 

Carl,

That could be, I could have understood incorrectly or maybe my old brain just did not remember what I heard correctly. If pushing on the plunger does not result in air or fluid being pushed up to the reservoir with the lever pulled back, then with a light pressure applied to the system by the syringe you could try slowly releasing the lever, again being careful not to have air or fluid spew out like a geyser.

 

Who knows, with those two jokers on "Car Talk" you never know when they are guessing and when they know what they are talking about, but they are comical to listen to.

[MiCarl]

It's called "back bleeding" and they make a tool to do it. It's very difficult and VERY messy. They made us do it in school to discourage us from ever doing it in real life.

 

If you're inclined to try (DON'T!) do not pull the lever. Marcarl is correct that that will prevent fluid from moving back to the reservoir. If you leave the lever released the tiny return hole in the bottom of the reservoir will be open. The air will come out that hole and eventually fluid. When there is a geyser that covers your bike in brake fluid the system is bled. Make sure to thoroughly wash the motorcycle immediately or your paint and plastic will be ruined.

 

In school we had lab partners. One of the team would push fluid into the system. The other would hold a rag and try (unsuccessfully) to catch the geyser of brake fluid. Then both would wash the motorcycle.

[M61A1MECH]

MiCarl

Good feed back thank you, I knew it could not be easy as Click & Clack made it out to be.

[Larry1963]

This post is at the right time, my 07 venture is sitting up because I ran the clutch reservoir empty and now cannot get it bled out. I borrowed from a friend a "power bleeder" where you pump it up and open the bleeder valve. My problem is I cannot get it to seal right. The other problem is, this is a very busy time of year and I have not had time to really sit down and do the job correctly. It is harder than I thought.

 

Let me bring up a problem I have noticed with the bike, or at least my bike, when the top of the reservoir is off and it is full there is a little room for fluid, the handle bars sit at such an angel that the fluid rest away from the holes. I thought about taking it off the handle bars and holding it up more level. I have the bike set up perfectly level when I do this to allow more fluid to be covering the holes. Whey they didn't put the holes at the far side of the reservoir, where with the handle bars pointed down more fluid would cover the holes.

 

Hopefully tomorrow I will have some time in the afternoon to tackle this job, if not off to the mechanic it has to go. I miss riding my bike.

 

Larry