Using a syringe to bleed

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I heard of this a long time ago and decided to buy one last week. I tried it on the rear first. All the old fluid was removed, the master cylinder was torn apart and cleaned up. Basically it was like a new system, clean hoses, empty reservoir, master, and caliper. The syringe was filled with fresh fluid and I watched to make sure no air bubble went up the tubing. I slowly pumped the fluid up thru the line until it filled up the reservoir. While still applying pressure to the plunger I closed the bleeder valve. I hit the pedal and NOTHING.

I figured that some air may have been getting in past the threads on the bleeder. So, I did my front brakes on Friday. I didn't tear apart the master tho, I just flushed out the old fluid, ran some new thru it, started empty again from the caliper. This time I wrapped the bleeder threads with some teflon tape. Pumped the new fluid up till the reservoir was full and tightened up the bleeder. I pulled in the lever and NOTHING.

Both times, I was able to get the brakes back with conventional bleeding. There was some air in the lines but it took a LONG time to get it out. In both cases it seemed as thought there was an air pocket in the master cylinder piston or somthing like that. That is how the brakes felt, and it would make sense because it took so long for the air to come out.

So, is there something wrong with my method or a step I am missing. Anyone have any pointers?

 

[naughtyG]

I've always done my brakes the conventional way without problems - I think it just works better as it's intended to work like that - ie the M/C pushes to fluid toward the calipers and gravity is part of it as far as air pockets are concerned.
I had to use the syringe method for the clutch line though as it was just impossible the normal way. I think (may be totally wrong of course) that the system must be full of fluid first, and then the reverse bleed gets rid of bubbles. I'm not sure it would work as a filling method, and apparently you proved that.

 

[4gasem]

I use a Mity-Vac and have ZERO issues with it. It's quick and easy. I finish off the job by doing it he old fashioned way to make sure all the air is out of the lines.

Chris

 

[veebooster]

I've only used the reverse method and never had a problem. I only take abit out of the master then open bleeder squeeze some in, then close and take out a abit more to prevent the overflow and repeat till the whole thing is flush with new fluid. Works like a charm brakes and clutch!

Dale #2592

 

[EvilD]

I used a 60cc syringe and some tubing to bleed mine, took all ob 15 seconds. Thats the only way i'll ever do it from now on.

 

[TURBOVMAX]

I heard of this a long time ago and decided to buy one last week. I tried it on the rear first. All the old fluid was removed, the master cylinder was torn apart and cleaned up. Basically it was like a new system, clean hoses, empty reservoir, master, and caliper. The syringe was filled with fresh fluid and I watched to make sure no air bubble went up the tubing. I slowly pumped the fluid up thru the line until it filled up the reservoir. While still applying pressure to the plunger I closed the bleeder valve. I hit the pedal and NOTHING.

I figured that some air may have been getting in past the threads on the bleeder. So, I did my front brakes on Friday. I didn't tear apart the master tho, I just flushed out the old fluid, ran some new thru it, started empty again from the caliper. This time I wrapped the bleeder threads with some teflon tape. Pumped the new fluid up till the reservoir was full and tightened up the bleeder. I pulled in the lever and NOTHING.

Both times, I was able to get the brakes back with conventional bleeding. There was some air in the lines but it took a LONG time to get it out. In both cases it seemed as thought there was an air pocket in the master cylinder piston or somthing like that. That is how the brakes felt, and it would make sense because it took so long for the air to come out.

So, is there something wrong with my method or a step I am missing. Anyone have any pointers?

Mike

What happens sometimes especially when you rebuild a caliper is that the caliper piston or pistons (front) are fully retracted in the caliper bore. Your first or second pump extends the caliper piston to the rotor which takes quite a bit of fluild. So in that case you may have a little trouble getting the air out the system. I usually use a little compressed air to push the pistons up against the rotor and then hook up the brake lines. Then back fill the system with the syringe.

 

[GREEN light BLITZ]

Well its a bit off topic and I never tried it for brakes but those big syringes are GREAT for sucking the fuel out of your float bowls if you dont feel like pulling your carbs and bowls.It sucks any crap from the bottom of the bowl (if there is any) much better than just letting them bleed out regularly.

 

[ssnsltd]

been using a vac or syringe for my hydraulics for years, only way to go.

 

[yukonerdave]

I'm gonna look into a Mityvac, but I need to bleed my brakes (for the first time) this week. Hanes manual says to put a hose on the nipple, then submerge the other end in a container half-filled with clean fluid. Is that just to prevent air from creeping up into the hose? I take it that you are forcing the old fluid out the nipple by compressing the lever, and running new fluid through the m/c. Is it necessary to submerge the hose in clean fluid? Also, is the syringe just used to empty the m/c before bleeding, or are you guys using one to suck the fluid out of the lines? Running new fluid through with the lever sounds like a pita - especially one your own with the left front caliper.

 

[veebooster]

The syringe is used to back- bleed the lines. Put clean fluid in your syringe and force the new fluid through the bleed nipples back up to the master cylinder. Make sure you don't overflow.....remove a little from the M/C to start.

Dale #2592

 

[yukonerdave]

Hmm - then you remove the old fluid from the m/c as it is forced up? Do you need a second syringe to remove it? Or do you drain the lines first and then force new fluid up?

 

[naughtyG]

Hmm - then you remove the old fluid from the m/c as it is forced up? Do you need a second syringe to remove it? Or do you drain the lines first and then force new fluid up?

You can do that but for the brakes you can just bleed the conventional way: clear tube over nipple, other end in pot or similar - no need to submerge. Open nipple, squeeze lever. Close nipple, release lever. Repeat until fluid is clean and bubble free. Don't forget to top up M/C reservoir as needed.

 

[veebooster]

Hmm - then you remove the old fluid from the m/c as it is forced up? Do you need a second syringe to remove it? Or do you drain the lines first and then force new fluid up?

Exactly.....I just take a bit out as I fill it. I don't take the level down to low to avoid air somehow getting in.

I even used this method when I put in new lines. Just back filled it and viola....that includes the clutch which can sometimes be a pain to get air free.

Get a good seal on the nipple though....u can image what happens when u start squeezing. I know!

Dale #2592

 

[yukonerdave]

I'm pretty good at getting a good seal on nipples...

 

[gamorg02]

u know autozone sells a 'mityvac' for like $30. i found bleeding very easy with them.

 

[yukonerdave]

I did NOT know that - thanks for the tip. I will stop by there on my way home today.

 

[gamorg02]

yea, i have the actual mityvac, but man those things make the job so easy. they even have the ones that have the pressure gauge on them so u know u have pressure without testing it.

let me know how u make out.

 

[gamorg02]

howd ya make out?

 

[yukonerdave]

Picked up the Mityvac from Autozone yesterday - $30 and it is actually a genuine MityVac. Not bad! Anyway, it hooked up smoothly and, as far as I know, worked great. I just bled the two front lines until clear fluid started coming out, and topped off the reservoir as I went along. No prob! Thanks again for the tips

 

[gamorg02]

easy wasn't it? just make sure there was still fluid coming out when you tightened the bleed valve back down, to ensure no air got in.