Brake Reservoir Fluiid Flow

[cv2065]

Went to bleed the brakes last night and I'm not getting any flow from the reservoir. I've got the Jamar triple brake reservoir roughly 3 inches from the footbox and the caps are slightly below the top of the 3/4" tube, so it really can't be raised any higher. I measured to the bottom of the reservoir from the floor and floor to where the fluid goes into the MC, and there is about 1/2" difference in favor of the reservoir. I'm going to be using a vacuum method of bleeding, so thought about trying to pull it all through to prime it but refrained since I'm not getting any flow but I am getting air pressure out of the MC fitting when I actuate the brake pedal. As a note, the front/rear reservoirs are the two closest to the footbox, the clutch reservoir is not connected right now and I've disconnected the front brakes MC brake line while checking for fluid.

What am I missing?

https://hosting.photobucket.com/images/c310/cv2065/IMG_9237.JPG?width=960&height=720&fit=bounds (https://hosting.photobucket.com/images/c310/cv2065/IMG_9237.JPG?width=960&height=720&fit=bounds)

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https://hosting.photobucket.com/images/c310/cv2065/IMG_9236.JPG?width=960&height=720&fit=bounds (https://hosting.photobucket.com/images/c310/cv2065/IMG_9236.JPG?width=960&height=720&fit=bounds)

[rvanstory]

If you're trying to do initial gravity bleed, make sure you remove the caps from the reservoirs (they are on in your pic)? If you leave the caps on, fluid will not flow just by opening the bleeders.

[CraigS]

Also the reservoirs could go higher. Look through a bunch of pics and see that the body is above the 3/4x3/4 tube. I can't say exactly how much higher, maybe it's only 1/2 inch, but anything will help. But before you move them, I'd remove the caps, as rvanstory says, and connect your vacuum source. I bet it will suck fluid for you.

[egchewy79]

as long as the fluid level in the reservoirs are above the MCs, you should be fine. you can try vacuum bleeding but I had pretty good luck w/ pressure bleeding, even w/o bench bleeding my MCs.
get an extra cap, drill and hole and attach a schrader valve. I used a ball/bike pump to around 5psi and cracked the bleeder valve and that was it. Keep an eye on your fluid level as you bleed.
any vertical loop-d-loops in your lines might trap air bubbles as well.

[cv2065]

Missed the caps being off as I wanted to gravity bleed first before using the vacuum. Let you know how it works out. Thanks guys!

[Norm B]

If the caps being off doesn’t work, try unbolting the reservoirs from the frame and lift them high enough to allow the air in the lines to purge back. Manually bleed the brakes with the reservoirs elevated. Once you’re satisfied with the brake bleeding, reattach the reservoirs.

HTH

Norm

[gbranham]

Just dispense with all the foreplay, and get a pressure bleeder, and be done with it. It's so simple and quick. I paid $60 for mine on Amazon.

[nashuanuke]

If the caps being off doesn’t work, try unbolting the reservoirs from the frame and lift them high enough to allow the air in the lines to purge back. Manually bleed the brakes with the reservoirs elevated. Once you’re satisfied with the brake bleeding, reattach the reservoirs.

HTH

Norm

yeah, this is what I did, albeit with how mine are attached it was much simpler, but temporarily elevating them for the bleed is definitely an option.

[nashuanuke]

Just dispense with all the foreplay, and get a pressure bleeder, and be done with it. It's so simple and quick. I paid $60 for mine on Amazon.

I have to say I tried this but could not get a tight seal on the bleed valves, I finally had my wife come out and help me do it the old fashioned way and it worked like a charm.

[gbranham]

I have to say I tried this but could not get a tight seal on the bleed valves, I finally had my wife come out and help me do it the old fashioned way and it worked like a charm.

Not sure I understand this comment. The only seal you need to pressure bleed is where the pressure bleed cap threads onto to the reservoir, in place of the reservoir cap. Are you talking about vacuum bleeding? I'm talking about pressure bleeding.

[cv2065]

Took the caps off and although no fluid at the calipers on a gravity bleed, I did verify air coming through the bleeder fittings when the pedal was pushed, so I know there are no obstructions and fluid did pump through the MCs. I have a vacuum bleeder which is what I’ll use tomorrow to see if I can pull it through. All else fails and I’ll elevate the reservoir as suggested.

[Dgc333]

Took the caps off and although no fluid at the calipers on a gravity bleed, I did verify air coming through the bleeder fittings when the pedal was pushed, so I know there are no obstructions and fluid did pump through the MCs. I have a vacuum bleeder which is what I’ll use tomorrow to see if I can pull it through. All else fails and I’ll elevate the reservoir as suggested.

I have had a vacuum bleeders, both hand held (Mity-Vac) and a pneumatic for many years. I have have only found them useful to initially get fluid into the system, I still had to do a two person bleed to get all the air out. The reason being is you will suck air past the bleeder threads. A couple of years ago I got a pressure bleeder, it has a reservoir that you put brake fluid in, you attach it to the system reservoir, pump it up to about 20 psi, open the bleeders, let the fluid run until there are no bubbles and you are done.

[cv2065]

I have had a vacuum bleeders, both hand held (Mity-Vac) and a pneumatic for many years. I have have only found them useful to initially get fluid into the system, I still had to do a two person bleed to get all the air out. The reason being is you will suck air past the bleeder threads. A couple of years ago I got a pressure bleeder, it has a reservoir that you put brake fluid in, you attach it to the system reservoir, pump it up to about 20 psi, open the bleeders, let the fluid run until there are no bubbles and you are done.

I had a Motiv style pressure bleeder but couldn't find a cap to fit the Jamar reservoirs like I had with the CNC version. They have a universal setup but haven't tried those.

[Nigel Allen]

Put some thread seal on the bleed screws when vacuum bleeding.

[Dgc333]

Put some thread seal on the bleed screws when vacuum bleeding.

I would be concerned that some of the thread seal would get into the brake fluid and have a negative reaction.

[Lidodrip]

I had a Motiv style pressure bleeder but couldn't find a cap to fit the Jamar reservoirs like I had with the CNC version. They have a universal setup but haven't tried those.

A member asked about how I pressure bled my system with Scott's Hotrods Triple Reservoir since there isn't a cap that fits those reservoirs. Below is my response and I suspect this approach would work in other circumstances when the bleeder cap is larger than the reservoir top.

I was not able to find a direct fit cap and I think the only real option would be to call Scott's to see if they would sell an individual cap. It would be pretty easy to drill a hole in the top and add a hose barb fitting. I did try to make one out of a PVC cap that I warmed up with a heat gun and used the reservoir to cut threads. It kinda worked, but did leak fluid so I abandoned it.

What I discovered that worked remarkably well was using the the cap that came with the system and just clamping it onto the top of the reservoir. I have the Smotive Pro 2L pressure bleeder with the European cap (45mm). On the inside of the cap, it has a wide rubber gasket. Although the cap is larger than the reservoir top, I could still center it on top of each reservoir (provided all the reservoir caps had been removed). I then used 2 small Craftsman clamps to clamp the cap to the top of the reservoir. The cap's rubber gasket allowed for a tight seal that did not leak and maintained pressure. Worked like a charm, easy to set up and I didn't have to buy an extra Scott's cap.

These are similar to the clamps that I used: https://www.sears.com/craftsman-6-in...p-00931481000P

Overall, it was very easy to do. Hope this helps.

James

[cv2065]

Quick update. The vacuum bleeder was amazing. I got the one from Harbor Freight for $90 after coupon. See link below. Once I got the routine down, literally took me about 5 minutes per side on the front and 10 on the back due to both bleeder screws. I dialed the compressor to about 80-90lbs and got great suction off of that. I didn't use the auto re-filler that came with the bleeder. I just refilled manually after each side. You do have to hold the bleeder fitting on the bleeder screw, or it will fall off.

https://www.harborfreight.com/pneumatic-air-operated-brake-bleeder-with-auto-refill-kit-57057.html

As has been mentioned, the vacuum method does pull air through the threads of the screw, but still seems that it's getting all of the air out of the lines. I completed each side then followed up with a cannister/gravity bleed and fluid came out clear with no bubbles. Pedal is rock solid but I'll do it again before getting on the road.

Best part is that I had no leaks on the first try. Let's hope that holds out. Thanks again for everyone's advice. Helped out greatly!

[Nigel Allen]

I would be concerned that some of the thread seal would get into the brake fluid and have a negative reaction.

You can be concerned all you like, but it doesn't happen. If you are pulling a vacuum at the bleed point, then brake fluid never flows over the thread sealer and into the slave cylinder.

Also, if you are using a continuous vacuum, thread seal is not necessary, as the vacuum will effectively pull fluid and air without issue.

I vacuum bled my brakes from dry in 10 minutes, no pedal pumping required.

Ultimately, vacuum bleeding and pressure bleeding are the same thing. It is just a pressure difference between the reservoir and the slave cylinder. With the lower pressure at the slave.

I however see the advantage of vacuum bleeding in that there is no mess or potential for fluid to be sprayed anywhere.

Hope that makes sense.

Cheers,

Nige.

[Mike.Bray]

I was not able to find a direct fit cap and I think the only real option would be to call Scott's to see if they would sell an individual cap. It would be pretty easy to drill a hole in the top and add a hose barb fitting.

That's what I did and Scott's was happy to sell me a spare cap. I drilled and tapped it for a pipe thread and got a hose barb from Ace Hardware. The only issue I had was getting a rubber gasket the correct thickness, too thin and the cap bottoms out and doesn't seal. Too thick and, well. Ended up with one from Ace about 3/8" thick and cutting it down.

It's kind of become the community bleed system around here with a few fellow forum members using it on their projects.

https://www.imagecoast.com/images/MichaelBray1/20220814163325mediumrotated.jpg