Pressure vs. Suction/Vacuum Brake Bleeders

[Jlaa]

Instructions say to clean using denatured alcohol which is what I do. You can buy a can at your favorite big box hardware store. I’m careful how I store the hose, making sure it’s not kinked or twisted.

Unfortunately this is no longer the case in California. Why has denatured alcohol been banned in California? (in 2019)
I picked up some Denatured Alcohol from a neighboring state.

FWIW I asked Motive what they recommend in lieu of denatured alcohol and this is what they recommended:

 

[500AMM]

Moisture buildup is the main reason for brake fluid degradation and frequent change, so I would think twice about using any water based mix for cleaning - that requires a 100% dry-up of the bottle and all connected parts. However, a good flush with isopropyl alcohol after the cleaning will remove any water locked up in the equipment.

 

[jftu105]

Just bleeding for two of my E320. My setup basically is similar to the Motive unit. I converted a garden sprayer and connected a long tube to a brake cap from junk yard. It took some modification to the old cap in order to attach the tube. I added a shraeder valve on the garden sprayer to check the pressure with a tire pressure gage. I pumped it to 20 psi and it is plenty to do the job.

I remove the brake reservoir cap and screw the cap with the tube to the brake reservoir. I do not tighten it tight initially. Pump some pressure, not high, to get the brake fluid to fill up the reservoir until it is full and then I tighten the cap. On the long tube I connected, I have a valve from Home Depot. I close the valve and pump the pressure to 20 psi, checked by the tire gage.

I then proceed to bleed all four tires by order, passenger rear, driver rear, passenger front, and driver front. I attach a short tube to the bleed fitting and use a 9 mm wrench to release it. The emptied brake fluid bottle is the container for the dirty fluid, placed inside an old toy bucket to prevent spills.

At the end of the job, I close the valve on the tube. I then pressed the schraeder valve to release the pressure inside the garden sprayer. Now, it has a reversed pressure differerence between the reservoir and the garden sprayer. Open the valve on the tube, the fluid inside the reservoir flows back into the garden sprayer.

When it stops flowing back, I remove the cap and hold it high to drain all the fluid in the tube back into the garden sprayer. Finally, I take a sringe to suck extra fluid inside the reservoir out and into the garden sprayer until it is below the max. line. In this way, I have very little waste.

I have used this unit for nearly 10 years and it is still holding up nicely.

jftu105

 

[gerryvz]

Moisture buildup is the main reason for brake fluid degradation and frequent change, so I would think twice about using any water based mix for cleaning - that requires a 100% dry-up of the bottle and all connected parts. However, a good flush with isopropyl alcohol after the cleaning will remove any water locked up in the equipment.

I wouldn't have any issue with using a water-based solution for cleaning (although I would personally use alcohol).

The interval between uses of a power bleeder, at least on my cars, is long enough that any water in the system that was still present when I cleaned it and put it away, that it would be long dried up before I used the bleeder again.....

 

[ace10]

Can you not use it dry for this application and avoid dirtying the vessel all together?

My Motive has never has any fluid inside it.

 

[gsxr]

Can you not use it dry for this application and avoid dirtying the vessel all together? My Motive has never has any fluid inside it.

Uh, no? Pushing air into the system kinda defeats the purpose. Fluid needs to be in the vessel so it can flow into the MC and refill it as you extract old fluid from each caliper.

 

[Jlaa]

Can you not use it dry for this application and avoid dirtying the vessel all together?

My Motive has never has any fluid inside it.

You could. It doesn't always work "dry" though .... Pressure vs. Suction/Vacuum Brake Bleeders | Tools and Shop Equipment

 

[ace10]

Uh, no? Pushing air into the system kinda defeats the purpose. Fluid needs to be in the vessel so it can flow into the MC and refill it as you extract old fluid from each caliper.

You fill the MC reservoir to the top, connect the pressure bleeder, then disconnect and refill as necessary.
Been doing it that way for a long time. You just can't let it get too low, else big problems, obviously. And it does increase the risk of cross-threading the cap.

I've done dozens of bleeds and changes without ever worrying about the Motive vessel becoming contaminated or having to clean it.

 

[gsxr]

You fill the MC reservoir to the top, connect the pressure bleeder, then disconnect and refill as necessary.
Been doing it that way for a long time. You just cant let it get too low, else big problems, obviously. And it does increase the risk of cross-threading the cap.

Ive done dozens of bleeds and changes without ever worrying about the Motive vessel becoming contaminated or having to clean it.

I get what you are doing... but OMG... so much unnecessary work! And no reason for it. Drain the reservoir afterwards, it only had clean/new fluid inside anyway.

 

[ace10]

I get what you are doing... but OMG... so much unnecessary work! And no reason for it. Drain the reservoir afterwards, it only had clean/new fluid inside anyway.

And you've got much greater chance of getting brake fluid where it doesn't belong.

 

[Jlaa]

You fill the MC reservoir to the top, connect the pressure bleeder, then disconnect and refill as necessary.
Been doing it that way for a long time. You just cant let it get too low, else big problems, obviously. And it does increase the risk of cross-threading the cap.

Ive done dozens of bleeds and changes without ever worrying about the Motive vessel becoming contaminated or having to clean it.

You can see at this link Pressure vs. Suction/Vacuum Brake Bleeders | Tools and Shop Equipment that bleeding it "dry" doesn't always work ... with some cars, the clutch circuit / brake circuit share the same reservoir, but the architecture of the reservoir (With the big wall in the middle) and the differing circuit pickup architecture conspires to make dry bleeding the clutch almost certainly guarantee the introduction of air into the clutch circuit. @RicardoD and I learned this the hard way a few weekends ago. It was alarming to press the clutch and have it fall to the floor and stay there!! Like, "uhhhhhh..... something is not right..."

Then we scanned a couple of forums relevant to the 964/993 (the cars we were working on) and there were mountains of posts like "Never ever ever ever bleed the clutch dry!!! Always bleed it wet!! All of us have made this mistake before!!!"

 

[ace10]

You can see at this link Pressure vs. Suction/Vacuum Brake Bleeders | Tools and Shop Equipment that bleeding it dry doesnt always work ... with some cars, the clutch circuit / brake circuit share the same reservoir, but the architecture of the reservoir (With the big wall in the middle) and the differing circuit pickup architecture conspires to make dry bleeding the clutch almost certainly guarantee the introduction of air into the clutch circuit.

My Lotus had a single reservoir. This was a track car that had complete brake fluid changes multiple times per year, and often multiple bleeds per weekend. For about ten years.

It's not as difficult as you guys are making it out to be.

On that car, the MC is under an access panel with painted surfaces on 3 sides, so I had to be extra careful with brake fluid. I've simply carried on that practice with some of the other vehicles, if I'm doing the brake fluid.

 

[Jlaa]

My Lotus had a single reservoir. This was a track car that had complete brake fluid changes multiple times per year, and often multiple bleeds per weekend. For about ten years.

Its not as difficult as you guys are making it out to be.

On that car, the MC is under an access panel with painted surfaces on 3 sides, so I had to be extra careful with brake fluid. Ive simply carried on that practice with some of the other vehicles, if Im doing the brake fluid.

Perhaps the lotus has a different reservoir / pickup architecture for the clutch.

 

[ace10]

I tried a Mityvac kit when I replaced the MC on my '67 FJ40. Maybe it was a bad unit, but I couldn't get the thing work. What a piece of garbage. It actually went into the bin.

 

[gsxr]

Its not as difficult as you guys are making it out to be.

Never said it was difficult. Simply unnecessary. The pressure bleeders are not prone to spraying fluid. But, to each his own.

I tried using the MityVac suction method and also found it a colossal waste of time. I don't understand why people bother. Edit: The primary issue I had was sucking air around the bleeder screw threads - this doesn't happen with pressure bleeding. Also, models with ASR... like all E500E... MUST use pressure bleeding.

 

[LWB250]

Never said it was difficult. Simply unnecessary. The pressure bleeders are not prone to spraying fluid. But, to each his own.

I tried using the MityVac suction method and also found it a colossal waste of time. I dont understand why people bother.

Actually, I've used the MItyVac method with a siphon bottle and it works just fine. I did it on almost every car I owned until I bought a pressure bleeder maybe 5 years ago.

Does make your hand sore but the time you get to that last wheel, but it works. At least it did for me.

I went to the MityVac after I had one of those bottle bleeders that used tire pressure to pressurize it popped open on me and nearly destroyed the paint on a front fender. Now whenever I bleed, even with the pressure bleeder, I put a towel over everything just in case.

Dan

 

[500AMM]

Moisture buildup is the main reason for brake fluid degradation and frequent change, so I would think twice about using any water based mix for cleaning - that requires a 100% dry-up of the bottle and all connected parts. However, a good flush with isopropyl alcohol after the cleaning will remove any water locked up in the equipment.

I wouldnt have any issue with using a water-based solution for cleaning (although I would personally use alcohol).

The interval between uses of a power bleeder, at least on my cars, is long enough that any water in the system that was still present when I cleaned it and put it away, that it would be long dried up before I used the bleeder again.....

You're right Gerry, and I guess that applies for a greater part of the DIY wrenchers. But I mentioned this based on experience with entrapped fluids in cavities inside small check valves, gauges etc.. which don't dry-up due to lack of air circulation.

OTH, is it really that important to clean this equipment so damn good? I mean next time it is the same mess over again and brake fluid is a PITA to clean off. I blow through with air and clean the exterior and put the entire brake fluid bleeder equipment away in a plstic bag, has worked fine for me.