Master Cylinder/ABS Control System Bleed

SPYDER918

MEMBER
2012 CHEVROLET CRUZE
1.8L
4 CYL
2WD
MANUAL
66,000 MILES

I replaced the clutch assembly on my car listed above LS model and had difficultly sealing a leak in the hydraulic line from the combination slave/TOB (Concentric slave). The leak was at the elbow (I say it's a tee) where the hydraulic line exits the bell housing into this plastic ell. The other end of the ell has the bleeder screw and in the middle of the ell is the feed from the reservoir. The leak was at the end of the hydraulic line where it seats inside the plastic ell. Well, after a lot of time and effort I managed to get it to seal. I then bleed the concentric slave with a pressure bleeder initially but to help speed things alone also used a vacuum pump at the bleeding screw on the plastic ell. And it appears all of the air has been removed from that system. The clutch feels good but I cannot start the car right now. It was starting at the touch of the key and running fine. Then one day I went to start it and suddenly I had a no crank situation. My feeling is its either the safely neutral switch or the key immobilizer. This is next after I resolve what I am about to ask you

With the clutch hydraulic system open for some time a lot of air got into the system. When trying to seal the clutch leak I was initially pressurizing the system dry (only air) just to see if it was holding tight. It was during that time I discovered the left front brake caliper had developed a leak. L replaced both front calipers.

Putting the pressure bleeder onto the same reservoir (the reservoir is shared between the clutch and the brakes) and started bleeding at the right rear brake. Well, I bled and bled and bled, an enormous amount of air with fluid has been purged from that point. I wasn't through there but when closing the bleeder screw it almost didn't close. It just kept turning until I took the wrench off and pushed the screw in while turning it with my other hand and finally it was screwing in. When it stopped I snugged it with the wrench and decided to move on. At least for now.

Going to the next wheel (left rear) I started bleeding it and got a similar response to a lot of air mixed with the fluid. I've probably put in 3.5 - 4 qt.’S of brake fluid. I’m getting clean fluid but I also still have air.

At that point, I started researching the issue and it seems that because of the time the system was open I introduced a lot of air not just to the brake lines but also to the master cylinder and the ABS modulator which, has enough lines coming from it to be confused with an octopus.

So, here is my dilemma: How do I get the air out of the entire system, from all places (components)?

Saying help would be an understatement.

Thanks,
Rick

7 Replies

4DRTOM

MECHANIC
467 POSTS

Hello,

That sounds like an awful lot of fluid to push through the system and still be getting air bubbles. You must be doing something wrong and letting air back in while your letting up on the brake pedal. Cars these day will self bleed with no need to pump the pedal. How are you doing you bleeding with two people or alone? When I am alone I'll fill up the reservoir and watch it doesn't run dry and crack the lines at the wheels and just wait. It will take a while especially in the rear but the lines will eventually run straight fluid out. Putting something under the wheel to catch the fluid is a good idea too.
Here is our article on how to properly bleed out the brakes give it a read and make sure your doing it exactly correct:

https://www.2carpros.com/articles/how-to-bleed-or-flush-a-car-brake-system

Let us know how you do, I will keep an eye out for your reply.

Tom

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Friday, November 27th, 2020 AT 10:12 AM

SPYDER918

MEMBER
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Hi Tom, and thanks for your response. It is a lot of air is what I was thinking. However, I'm using a pressure bleeder so no pedal manipulation, that's why I'm confused. And I see no leaks. However, the line from the pressure bleeder has a constant space in the tubing which, has an air gap in it. I wasn't real concerned about it as that air will not get through the reservoir filled with fluid (actually never moves except an inch or two up and down with pressure changes). I was wondering if the hose connection at the bleeder screw (although it seems fairly snug) was drawing air in at that point and I was thinking of wrapping the screw with some special tape (like Teflon but for more reactive fluids). Also, the system was open for some time with the difficulty I had getting a seal at the clutch hydraulic line from the concentric slave to the plastic connection which feeds the brake fluid to the slave and also has a bleeder screw.

And then finding a leak in my left front caliper (as I stated I replaced both front calipers). But since the system was open for some time and I was pressure testing the leak from the slave with air from the pressure bleeder that a lot of air got into the master cylinder and the ABS module. I don't really, until now, have any experience with the multiple circuits in an ABS module.

Do you think the above hypothesis has any validity. If not I cannot think where all this air is coming from.

I'm hoping you can shed some light on it.
I'd like to finish before we get a snow storm.

Thanks,
Rick

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Friday, November 27th, 2020 AT 5:57 PM

4DRTOM

MECHANIC
467 POSTS

Hi Rick,

I think the pressure bleeder is your entire problem. If your alone I would gravity bleed it or if anything pull the fluid to the caliper with a hand gun style vacuum pump. We're going to have to assume there is air in the abs manifold too so you will have to crack each line at the manifold first and make sure the manifold is air free. But for now can you send me the model bleeder you are using so I can look into it specifically and we can go from there? Bleeding this car shouldn't be an issue its a pretty straight forward thing.
Tom

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Friday, November 27th, 2020 AT 11:40 PM

SPYDER918

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I made the mistake of writing my update on here and was close to being done when I had to leave the coffee shop as they were closing. When I got home the page had minimized. I tapped on it to enlarge it but that also caused it to refresh and what I had written was gone.
So, I'm going to another app to rewrite.
Rick

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Sunday, November 29th, 2020 AT 8:00 PM

SPYDER918

MEMBER
8 POSTS

Hi Tom,

Sorry, it has taken me so long to get back to you after my last attempt went somewhere in cyberspace.
Anyway, It went something like this. l haven’t had a lot of time over the weekend to work on the car. However, I did manage to continue the bleeding process.
I gravity bled the master cylinder with a shop towels underneath. When I finished one or the towels was soaked another partially although, I what I noticed was not a heavy drip but a steady one. Especially, from the port closest to the firewall. The other port didn't seem to drip as much but it was definitely wet around it. After about an hour I took an adjustable rod from my bike repair stand which, holds the front wheel steady. Adjusted so it could take the place of my foot when wedged against the seat. I then depressed the brake pedal slowly about � of the way to the floor. Then put the rod in place, went back to the master cylinder and tightened the port connections. Then released the rod. I repeated this procedure 4 times.
At this point I moved on to the ABS Manifold. Again, placing shop towels under it and loosened all 4 connections (I have attached pictures of these and the pressure bleeder you wanted). I let these bleed for about 50 minutes but had to go.
Now I'm sure I had some other info in the first attempt but cannot remember right now.
I did watch a video which 1) helped refresh techniques I had forgotten.
2) He uses the same bleeder as mine. Except mine is older and he has some fancier fittings for the reservoir which, were not even offered when I bought mine. Mine is a black plastic (threaded � initially, it came with a 3 tab which was wrong so, we exchanged it for the correct screw on type). Also, be does not recommend using the plastic ones as they tend to warp causing a bad seal. Also, he reminded me of cutting all the ends of the tubing for a good fit as they swell. I was only cutting an end if I noticed something wrong. He also has quick disconnects in the hose between the reservoir and the tank. I tried to find a swivel coupling (to keep the hose from twisting when screwing it onto the reservoir) but couldn’t in that small size. So, I wound up using a union which works and would be okay if I could have found a brass one as they are smaller (I believe). I wound up with a galvanized union which seems to work ok and spraying with a soap solution appears tight. But it is big and heavy.
He also mentions about getting air in the ABS spool valve and that it was a nightmare for a friend of his to get out. But if air does get in their can't I fool the system by bring it to an impending lock or an actual lock of the wheels to activate the spool hence, getting the air out that way???

If your interested in looking at this video: https://youtu.be/_uavUdIT2-o”

I've attached pictures of the bleeder you wanted and a couple of the master cylinder and ABS Manifold.
Okay, I've got to run to get some more bleeding done on the car.
Thanks.
Rick

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Master Cylinder/ABS Control System Bleed

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