Brake Bleeding, Hand Pump, Air Bubbles, Grease on Valve?

[YoshiMoshi3]

Whenever I bleed brakes with a hand pump, I ALWAYS get bubbles. Someone has told me that this is unavoidable, because air is introduced through the threads of the bleeder valve when it is loosened, and that there's not much you can do. I have heard some people put grease around the valve, and this will solve the problem. I figured I would give this a try. Is there a certain type of grease I should use or not use? Could some of the oils from the grease seep past the threads and enter into the brake fluid within the calipers, is this a problem, mixing grease and brake fluid?

 

[M.Brane]

If you're bleeding with vacuum any grease that does get past the threads will just get sucked out the bleeder. Any grease that's handy will do the trick just don't go crazy with it.

I prefer manual/pressure bleeding as it's less likely to create bubbles in the process. Slow, and steady so you don't cavitate the fluid.

 

[alwaysFlOoReD]

I use engine vacuum and a mason jar. Long tube from mason jar to engine vacuum tree. Short clear tube from mason jar to bleeder valve. Just drill 2 holes that the tube barely fits thru. The mason jar isolates the brake fluid from the engine. The vacuum works pretty quick and it's easy to feel when you see new fluid. There are bubbles from air getting past the threads but I don't worry about it.

 

[39CAMC]

For whatever it is worth, most people overcomplicate brake bleeding. We do track prep at our shop so I probably do 100 brake flushes/bleeds a year. 98% of them, I use a bottle like this:

I use a turkey baster type of extractor to remove as much old fluid from the master cylinder as possible.
Fill with new fluid, go do RR, open bleeder about 1/4 turn and hang bottle making sure there is enough fluid in the bottle to cover the hose inside.


10-20 slow pumps per corner. Refill master between corners. I usually go RR, RF, LR, LF except Honda's which like a different order.

Quick, efficient, doesn't require 187 master cylinder adapters, can be done alone, does a good job. Doesn't waste 4 gallons of brake fluid.


This works for almost all cars except some of the newer electronic brake systems (which have built in bleed programs) and also works for most simple part replacements like hoses or calipers down stream of the ABS.

I don't put grease on the bleeder threads or a bunch of other gimmicks.

Keep it simple folks.

DaveW

 

[Torque&Recoil]

I used to use the Mityvac hand pump method. Yes, grease on the base of the bleed screw to keep air from getting sucked in. Any grease will work. In my experience, it doesn't get sucked into the brake system, so exact type of grease doesn't matter.

OR, a better solution is to remove the bleed screw, wrap it in teflon tape, then re-install. The teflon keeps air from sneaking around the threads and no grease is required. That method works well.

I have also done 39CamC's method, and - you bet - it works just fine.

However, today, I mostly pressure bleed. It just works better for me, alone. Buy an extra cap, drill hole, attach male pneumatic fitting, hit it with 20 psi air, open bleed screw at caliper. Done. I don't need to crawl over the roll cage to get into the race car. Just... done.

 

[signcrafter]

I have the mityvac MV6835 vacuum brake bleeder and like it for most flushing. It also gets bubbles from sucking air in from around the threads of the bleeder. It's not a big deal because it gets sucked into the bleeder hose. I also was concerned when I first got it 15 or so years ago and did some reading on them. You can put brake grease on the threads if you feel the need, I never worried about it or tried it so not sure if it seals all the air out or not. I just **** until I see clean fluid. If I need to bleed the brakes because air got in changing a part I just **** fluid until I think it's good and then see how the pedal feels. Never had an issue.

I did recently pick up a pressure bleeder off amazon and it worked on a 2019 silverado I replaced the ABS pump in but didn't have an adapter that fit good on a newer explorer I was doing a flush on. I see some chinese electric pressure fluid bleeders on amazon and a pretty big adapter set so may look into one of them in the near future.

 

[driftpin]

Teflon tape on the bleeder threads helps.

Well while I was fixing dinner, a couple of similar posts.

I use an irrigation syringe and a short length of 1/4" clear plastic tubing, filling the syringe with brake fluid and filling the master cyl trough the bleeder valves. That's what I do on my non-ABS motorcycles for brakes and hydraulic clutches.

 

[Beerhippie]

I bought one of these:



and I'm never looking back! Find the right adapter (the hard part), attach to master cylinder fill port, fill with brake fluid. A few pumps and start opening bleeders. Fool-proof and flawless bleeds.

 

[theoldwizard1]

For whatever it is worth, most people overcomplicate brake bleeding. We do track prep at our shop so I probably do 100 brake flushes/bleeds a year. ...

I use a turkey baster type of extractor to remove as much old fluid from the master cylinder as possible.
Fill with new fluid, go do RR, open bleeder about 1/4 turn and hang bottle making sure there is enough fluid in the bottle to cover the hose inside.

10-20 slow pumps per corner. Refill master between corners. I usually go RR, RF, LR, LF.

I don't understand why people make it so complicated and need "special" tools. (My bottle is a 1/2 liter soda bottle.)

Important things to remember

• Keep the master cylinder full (check after each wheel)
• Make sure the tube in the bottle is BELOW the level of fluid in the bottle
• I actually use a small spring hose clamp to make sure the bleeder hose stays on the bleeder screw/******.

 

[Beerhippie]

I don't understand why people make it so complicated and need "special" tools. (My bottle is a 1/2 liter soda bottle.)

Important things to remember

• Keep the master cylinder full (check after each wheel)
• Make sure the tube in the bottle is BELOW the level of fluid in the bottle
• I actually use a small spring hose clamp to make sure the bleeder hose stays on the bleeder screw/******.

Because it was about thirty bucks? And is far less complicated than any other way I've bled brakes in the last fifty years?

 

[signcrafter]

I don't understand why people make it so complicated and need "special" tools. (My bottle is a 1/2 liter soda bottle.)

Important things to remember

• Keep the master cylinder full (check after each wheel)
• Make sure the tube in the bottle is BELOW the level of fluid in the bottle
• I actually use a small spring hose clamp to make sure the bleeder hose stays on the bleeder screw/******.

It's OK you don't have to get it. Complicated has different meanings to different people. "Special" tools make it less complicated in my opinion. I don't have to be getting up and down from under a vehicle to pump the brakes or check if all the dirty fluid is out. To me that is less complicated for minimal expense.

Personally I don't understand why someone would want to buy a "special" box and pay to have a POTS as a land line. I just carry my cell phone and have a phone wherever I go. But I don't have to understand why you want to do that if you want to.

 

[Chipm]

I like to pressure bleed, but the Mityvac system hoses are ****** and leak after a while, usually making a big mess. Recently I have tried using the Mityvac fluid extractor to vacuum bleed. Gets a TON of bubbles, but I learned that for a fluid exchange it doesn't matter. For component replacement I still pressure bleed so I can watch for bubbles to disappear.

I used to do the 39camC method, but it was not working well on a few different caliper replacements. The pressure bleeder knocks those out in about ten seconds.

 

[mm08822]

I've used the Mityvac setup for 20 yrs. Pressure bleed is the way to go. Makes it a single person job.

Only complaint with Mityvac is the hose connections get brittle after sitting for some time and need to get cut off and use fresh hose a few inches downstream.

 

[sz0k30]

I've always had good luck just gravity bleeding. One man job. Take the cap off the m/cyl, have good fluid level. Start at the right rear wheel, loosen bleed screw & wait for the fluid to flow. And work your way around: LR, RF then LF.

 

[Jeepster04]

I've been using the Mityvac vacuum bleeder for around 14 years, never had an issue. Sometimes I will put some silicone grease around the threads but lately Ive been too lazy to. I would like to try putting some teflon tape on them, never tried that.

The whole pressure bleeder thing makes me feel like I'm forcing moisture into the brake fluid.

 

[Rusted Nut]

If you’re using a vacuum bleeder, use the least vacuum pressure you can; this will greatly reduce sucking in small air bubbles. When you are actually sucking air out of the system, the bubbles will be reasonably large. Many very small bubbles will be from leakage, not out of the brake system itself. I just don’t worry about the small leakage bubbles.

 

[Chipm]

The whole pressure bleeder thing makes me feel like I'm forcing moisture into the brake fluid.

The pumps made for brake bleeding do not introduce air into the fluid. Not sure about the DIY modified-weed-sprayer setups.

 

[theoldwizard1]

Personally I don't understand why someone would want to buy a "special" box and pay to have a POTS as a land line.

Not for me ! It is for a neighbor. I have FREE VOIP for my home line !

 

[signcrafter]

Not for me ! It is for a neighbor. I have FREE VOIP for my home line !

It was an example of how just because you do it the old fashioned way and you don't see why others want to do it the easy way with "special" tools doesn't mean others can't see it. You really wouldn't understand when I have to get out the "special" scan tool to do an abs bleed or to put vehicle with electric parking brake in service mode to change the brakes.

 

[Chipm]

Vacuum in action:

 

[gizardlizard]

I’ve been using a Speedi bleeder for years. Love it. No mess at all and it bleeds brakes for me while I’m doing other pm work. You can even use air pressure from a tire if needed if you don’t have compressed air close by.