tiborrules

I have a 2015 Z51 C7 and need to bleed the brakes by myself so i used a Motive power brake bleeder and purchased the brake bleeder adapter (#1118 that is 1.9" diameter). After making sure the master cylinder bleeder cap was on and tight I pumped up the bleeder to 15 psi with no leaks. While bleeding the rear brake all of a sudden the brake fluid started pouring out around the master cylinder cap. This happened three different times causing a large mess in my garage, loss of 1L Castrol SRF brake fluid and brake fluid spilled in my engine compartment.

I don't have anyone to help me bleed the brakes and want to use the power bleeder. Does anyone have any ideas why my adapter leaks as it is supposed to fit my car? What are other C7 owners using for a master cylinder adapter cap? I don't want to experience this problem again. Thanks!

Harris

I have had the same issue! Motive bleeder worked great on my 08 but have had trouble with the C7's.

The HACK

No problem with mine, the instruction says to use the THICKER of the two rubber gaskets. Which one did y'all use?

With the thicker of the two rubber gaskets, it requires significant force to push down, seal and twist to close the cap. But even at over 26PSI there were zero leaks.

Harris

I have used both, I have a new cap to try next time

tiborrules

I used the thicker of the two gaskets and you are right, it did take a lot of force to seat and twist it. No leaks at first but after 30 seconds or so when I was bleeding the brakes, it would begin to leak pretty bad.

wspo

That should be the right adapter. It came with two gaskets have you tried the thicker one? I have been using the motive bleeder for quite a few years on several different vehicles. Getting a perfect seal with the adapters has always been problematical for me. To eliminate the mess and waste of brake fluid I only use the power bleeder to pressurize the master cylinder. No fluid is put into the power bleeder. Top off the master cylinder with fluid after you bleed each wheel. Then re-pressurize the master cylinder and bleed the next wheel. As long as you don't let the master cylinder run dry you are good. A slight leak of air at the adapter does no harm using this method. No wasted fluid is left in the bleeder. Unless you are doing several vehicles I see no advantage to putting the fluid in the pressure bleeder. Good luck.

tiborrules

Ok. That's a different approach I hadn't thought of will give it a try.

Harris

That's what I have ended up doing as well, works great no mess.

djnice

Mine leaks too. So I don't put fluid in the bleeder either.

tiborrules

I guess I'll use the dry power bleeder approach to be safe. It just takes longer but is worth it by not creating a mess and loosing expensive new fluid. Thanks for everyone's comments.

Bill Dearborn

Not sure why it takes longer. I suck all of the fluid out of the master before starting using a compressor driven vacuum tool. Then I refill with new brake fluid. I can bleed the right rear, left front and left rear before needing to put more fluid in the master. To put more fluid in the master is only a matter of a couple of minutes. I can choose to do that after the left front is bled or after the left rear.

What I don't have to do is clean up a mess inside the motive and I don't have to worry about wasting expensive brake fluid. I use Ferodo Racing Brake Fluid which runs in the mid $20 range and has a dry boiling point about 25 degrees higher than SRF.
Bill

tiborrules

How much fluid does it take you to do a complete flush? I flushed my brakes yesterday and you are right as it is definitely a cleaner method. I stopped and refilled my master cylinder more often though as I was afraid of running the fluid too low and maybe getting air in the system. I didn't think about sucking the fluid out of the master cylinder first.
Good ideas. Thanks.

Avanti

I've not had any reason to bleed the C7, but with other vehicles, some with problems bleeding in other ways, I have vacuum bled with complete success. This, in a sense, is attacking the problem from the other end.

Additionally, I have used power-bleeders (long enough ago I'd forgotten), sometimes successfully other times not. I found that if I just used the thing as a source of pressure to the M/C and the system, i.e., not putting fluid in it, but instead being sure to monitor the fluid level in the M/C and refill appropriately I avoided potential and real messes as you have described.

The HACK

The most "efficient" way is still the pump and bleed with a buddy, IMO. We were able to completely flush the brakes on his Toyota FJ cruiser with less than 3/4L of brake fluid, and that's with us being conservative and over-bleeding the system. I suspect a little over 1/2L would have been enough to flush all 4 corners on his FJ Cruiser.

With a pressure bleeder it's a bit of guesswork, but I managed to flush the DOT3 from factory with Motul RBF 600 using only a little over 2 bottles (1L total). Unfortunately, if you crack that 3rd bottle, there's really no "good" way to store it for a future flush. So 1.5L it is. I think if we pumped and bled, I could have easily flushed the whole system with less than 1 total liter.

Unfortunately it's hard to find a friend willing or have the time and patience to sit in the car while it's up in the air patiently pumping the brake while you scream "closed!" and him screaming "pressured" through an open window.

village idiot

I just go to 10psi. It's plenty of pressure to bleed the brakes. No leaks. 15psi gets really sketchy.

For how infrequently you need to bleed the entire system, it's worth $15 if you have to crack the third bottle.

X25

As with others I also only use motive bleeder with no fluid in it. The brake reservoir on these cars is massive, and you don't even need to refill more than once to bleed the brakes. The brake fluid is highly corrosive; not worth the risk spraying it everywhere.

Cosmo Kramer

Bill Dearborn

Not quite two containers of the Ferodo fluid. That is with sucking all of the old fluid out of the reservoir using a Vacula tool. I used to use the Vacula to bleed the brakes but it sucked the fluid out of the brake system so fast I had issues with it pulling all of the fluid out of the reservoir thus getting air into the ABS unit. Much faster than a hand pumped vacuum bleeding system. I don't see any difference in using the Motive or the Vacula they both apply a pressure differential to the brake system, the Vacula just operates so fast you need somebody observing the master cylinder ready to yell stop.

Bill

Oh4GTO

Didnt have much luck with my motive. The cap broke at only 16 psi. On top of that a piece of the rubber gasket went into the res which I was able to fish out. I'm sticking with my simple clear hose with a one way check valve.