how do car makers fill their brake system?

[windeye]

It's about time that I need to flush (or replace) the brake fluid in one of my cars (a 2007 Mazda3). I've done it in the past using a two-man method, and a vacuum bleeder. The vacuum bleeder sucks air in from around the loosened bleed screw. I also suspect (not proven) that if the vacuum is too strong, it might suck air in from around the piston seal.

I've read a lot about pressure bleeding using, say a Motive bleeder, and the different uses of either putting brake fluid in the Motive pump or just using air pressure. My worry is that the master cylinder reservoir is not very strongly attached to the master cylinder, and it might pop out even at 15psi pressure applied (I really don't know how much pressure diff the reservoir can withstand).

So there comes the question, how do car makers fill the brake system, and make sure no sir in it? Thanks.

 

[Johnny248]

I don't know, but I've installed speed-bleeders on a couple of my car and they are great! best idea ever. Just crack what bleeder you want, jump in the car and pump away. There is a check valve in them so when you let your foot off the brake it prevents air from entering.

 

[jaj]

I did the same on two our our cars. For about $10 a pair, they're awesome. I got the Russell ones, by the way.

Of course, if you only do it once every three years, get a friend or spouse to sit in the drivers seat and pump the pedal while you man the wrench and the bleeder bottle. If you can get your spouse to join you, it's a great bonding experience and you get a little more appreciation for the hard work you put in making sure everything's running safely.

Originally Posted By: Johnny248
I don't know, but I've installed speed-bleeders on a couple of my car and they are great! best idea ever. Just crack what bleeder you want, jump in the car and pump away. There is a check valve in them so when you let your foot off the brake it prevents air from entering.

 

[MichiganMadMan]

It's a pretty complex setup from what I have seen.

They can also "cheat" and fire up the ABS pumps to crank out the fluid if the need to. I don't recall anyone breaking bleeder bolts loose on the cars/trucks, but I'm usually looking at the "marriage" area where the chassis meets the body, or at the End Of Line tests. If I happen to be in a plant again soon, I'll have a gander. It's probably a spendy machine that does it in an automatic cycle.

I also use the 2-man method for bleeding brakes, but I use a turkey baster or similar to suck as much fluid out of the reservoir as I dare before I refill it and bleed the lines. Saves pumping the brakes a million times just to get rid of the volume.

 

[HTSS_TR]

Originally Posted By: windeye
It's about time that I need to flush (or replace) the brake fluid in one of my cars (a 2007 Mazda3). I've done it in the past using a two-man method, and a vacuum bleeder. The vacuum bleeder sucks air in from around the loosened bleed screw. I also suspect (not proven) that if the vacuum is too strong, it might suck air in from around the piston seal.

I've read a lot about pressure bleeding using, say a Motive bleeder, and the different uses of either putting brake fluid in the Motive pump or just using air pressure. My worry is that the master cylinder reservoir is not very strongly attached to the master cylinder, and it might pop out even at 15psi pressure applied (I really don't know how much pressure diff the reservoir can withstand).

So there comes the question, how do car makers fill the brake system, and make sure no sir in it? Thanks.

I used both Motive Power Bleeder and Mityvac 7201 to bleed the brake of my cars. The Mityvac is much easier and the brake is as firm as it can be without any air in the system.

I bought a thick flexible hose from Ace Hardware store and it fits the bleeder screw much better, almost no air around the bleed screw is sucked into the Mityvac when I pumped it 4-5 times. You want good vacuum but not too strong.

 

[scurvy]

Having used a hand-held Mityvac, the you-pump-I-turn two-person method and a Motive pressure bleeder, I'm glad I invested in a Motive. Worth every cent and works like a charm.

 

[cchase]

Originally Posted By: scurvy
Having used a hand-held Mityvac, the you-pump-I-turn two-person method and a Motive pressure bleeder, I'm glad I invested in a Motive. Worth every cent and works like a charm.


Same here. Tried them all, the pressure bleeder is hands above the easiest, cleanest method.

 

[windeye]

Originally Posted By: cchase
Originally Posted By: scurvy
Having used a hand-held Mityvac, the you-pump-I-turn two-person method and a Motive pressure bleeder, I'm glad I invested in a Motive. Worth every cent and works like a charm.


Same here. Tried them all, the pressure bleeder is hands above the easiest, cleanest method.


So how much pressure you dial in with the Motive blender?

 

[The Critic]

GMBoy should know this one.

Originally Posted By: windeye
Originally Posted By: cchase
Originally Posted By: scurvy
Having used a hand-held Mityvac, the you-pump-I-turn two-person method and a Motive pressure bleeder, I'm glad I invested in a Motive. Worth every cent and works like a charm.


Same here. Tried them all, the pressure bleeder is hands above the easiest, cleanest method.


So how much pressure you dial in with the Motive blender?


I usually use 15-20psi.

 

[windeye]

Originally Posted By: The Critic
GMBoy should know this one.

Originally Posted By: windeye
Originally Posted By: cchase
Originally Posted By: scurvy
Having used a hand-held Mityvac, the you-pump-I-turn two-person method and a Motive pressure bleeder, I'm glad I invested in a Motive. Worth every cent and works like a charm.


Same here. Tried them all, the pressure bleeder is hands above the easiest, cleanest method.


So how much pressure you dial in with the Motive blender?


I usually use 15-20psi.


Thanks. Obviously it worked for you.....I was wondering if the master cylinder cap thread can hold 15-20 pound of pressure....how did the fluid flow at the rear right wheel?

Anyway, I wanted to try the pressure bleed method, but I need to get a master cylinder cap and make an air tight fitting on it. Read some horror stories of brake fluid spill, so I might just use air pressure.

On the vacuum bleed method, what I did to seal the bleed screw thread is to 1st cut the tip of the screw off (bought a new one) so the hole is straight and bugger, and then tight fit a piece of rubber hose (about 1/4 in long) so I can screw it in. The rubber hose piece serves as a gasket and stopper for the screw. I still did not like it, because I had to swap the screws, and is messy.

 

[Bamboooo]

I wonder if a guy could take a spare master cylinder reservoir lid, and drill a hole in it. Then, in the hole, add either a valve stem, or a air hose quick-connect. Hook up the air hose to it, and put about 15 psi, or so, into the reservoir. What do you think? Would this be a "poor mans" Motive? I think you could have less than 10 bucks in parts. Hmmmmmm........

 

[scurvy]

Originally Posted By: windeye
So how much pressure you dial in with the Motive blender?


~10 psi; 1 bar (14.5 psi) maximum.

Originally Posted By: Bamboooo
Would this be a "poor mans" Motive? I think you could have less than 10 bucks in parts.

Plans exist in several places for exactly that, typically made from a garden sprayer.

 

[The Critic]

Originally Posted By: windeye


Thanks. Obviously it worked for you.....I was wondering if the master cylinder cap thread can hold 15-20 pound of pressure....how did the fluid flow at the rear right wheel?

Anyway, I wanted to try the pressure bleed method, but I need to get a master cylinder cap and make an air tight fitting on it. Read some horror stories of brake fluid spill, so I might just use air pressure.

On the vacuum bleed method, what I did to seal the bleed screw thread is to 1st cut the tip of the screw off (bought a new one) so the hole is straight and bugger, and then tight fit a piece of rubber hose (about 1/4 in long) so I can screw it in. The rubber hose piece serves as a gasket and stopper for the screw. I still did not like it, because I had to swap the screws, and is messy.


The flow was great. This was on an old Saturn though.

For vacuum bleeding I would follow-up with 2-3 manual bleed "sessions" at each corner. I have had a lot of problems with vacuum bleeding resulting in a low pedal.

 

[Vikas]

How many manufacturer sell brake reservoir cap cheap?

 

[jaj]

I have three pressure bleeders in my garage, and I still decided to switch to the Russell Speed Bleeders. That was after a defective hose clamp slipped off the fitting on the top of the bleeder bottle with a liter of brake fluid and 20 PSI of pressure in it. It happened right in front of me and soaked me (face first) and the whole end of the garage and the car with a brake fluid fountain.

 

[Ken2]

Quote:
The vacuum bleeder sucks air in from around the loosened bleed screw
A smear of heavy grease around the threads of the bleed nipple will seal air out, and the grease won't get sucked past all those threads and into the system. Or, remove the nipple, wipe dry, add a coating of pipe thread compound, and re-install.

 

[mechtech2]

Vacuum bleeding is super simple.
No adapters needed, and WAY less expense.

 

[doitmyself]

Originally Posted By: Bamboooo
I wonder if a guy could take a spare master cylinder reservoir lid, and drill a hole in it. Then, in the hole, add either a valve stem, or a air hose quick-connect. Hook up the air hose to it, and put about 15 psi, or so, into the reservoir. What do you think? Would this be a "poor mans" Motive? I think you could have less than 10 bucks in parts. Hmmmmmm........

You would need a very good air dryer system to hook up directly to an air compressor (they condense a lot of water in the tank).
Originally Posted By: Vikas
How many manufacturer sell brake reservoir cap cheap?

Most good auto parts stores have aftermarket caps for $5-$7. I made a cap to pressure bleed with my Mityvac 7201.
Here are 2 of many DIY articles on homemade brake bleeders:

http://faculty.ccp.edu/faculty/dreed/campingart/jettatech/bleeder/index.htm
http://www.bmw-m.net/TechProc/bleeder.htm
HOMEMADE CAP:

 

[Bamboooo]

Thanks doitmyself! I already have a Mityvac 7201, but I think I will build one of these contraptions, too. Really, all I need is the spare cap and a hose barb adapter.
Oh, by the way, the second link you posted looks like a home made mobile meth lab. Don't get pulled over with all that stuff in your car, or you'll be cuffed & stuffed!

 

[HTSS_TR]

Originally Posted By: mechtech2
Vacuum bleeding is super simple.
No adapters needed, and WAY less expense.

I agree. I had Motive Power Bleeder with adapters for bleeding European and import cars. I used it on E430 and LS400, it was pain to install the adapter to the LS400 and it didn't work very well for rear brakes. Installing the adapter on the E430 was easy but it took a long time to bleed rear brakes.

The Mityvac 7201 works flawlessly on either car, so easy and so fast.

What did I do with Motive Power Bleeder with 2 adapters ? Sold it on Ebay and Craigslist for a small profit.