I flush my brake fluid every 2-3 years as normal maintenance. My 1991 Z28 unfortunately has rear drum brakes with the terrible recessed bleeder design. I've always bled them by using a socket and taking a bath in brake fluid while someone else pumps the pedal. After this weekend I've vowed to never do this again...

I see online people mentioning speed bleeders are a good way to fix this issue. It extends the bleeder out enough a standard wrench can get on it and I can bleed it with one person. But I haven't been able to find a specific sizing or brand post on this website. Anyone know which size and brand I should get to make this process less painful next time?

 

I generally just put a big pan under the wheel, open the bleeder, crack open a cold one, and sit back and watch. When my cold one runs out, before I get a new one, I fill the master cyl back up. Right rear first, until fresh brand-new fluid appears, then left rear, then RF than LF.

I HATE work. I don't want to work hard. I don't even want to work smart. I don't want to work AT ALL. In "my" perfect world (haven't quite completely got there yet) I just wanna sit back and do NOTHING while I watch the work DO ITSELF. Doesn't get much better than that, except that I have to ... watch.

Which is what I just described, amounts to. Just watch the work do itself. Be patient, it'll get itself all done for you.

 

Get a proper bleeder wrench too. You always have the option n of a helper and tubing and an easy old school bleed.

They are M10 x 1.5. Some of the speed bleeders have different lengths available in the same size. I do recommend the longer ones. Even on clear access, on some applications, the shorter ones thread into the caliper enough they don't seat without seeming like they'll grind the hex.

If you do get so inspired, aftermarket extra long bleeders, the right size ball bearing, spring, and roll-pin let's you make your own.

 

Don't need a helper, don't need speed bleeders.

1. Push the pistons all the way in on the front calipers.
2. Suck all the fluid out of the master with a sucking device.
3. Fill the master w/fresh fluid.
4. 4.1. EXCEPT, I do all 4 at the same time. B/c I also hate work and I don't want to wait the amount of time required to do 'em one at a time. I like to do that job in about 10 minutes....not 40.
See, I get paid salary (for my boss-of-mechanics'-job), so...the faster I get things done, the sooner I get to go home. Thus, I've learned how to do things the FAST way. Throw the pans under the corners, open up the bleeders, wait for clean fluid to show (keep an eye on the fluid level!), close 'em up.

5. Pump the pedal to move the caliper pistons back out to the rotors
6. Top up the master reservoir.

 

What Sofa said but put a hose on the bleeder then into a pan or bottle. No need to make a mess that you have to clean up. I HATE A MESS.

 

I'm with Sofa and BBCSwap. Gravity bleed. I did all four corners of my car this way last year. Worked great. With my dark old fluid, it was easy to tell when the new stuff arrived. Used a clear vinyl hose from the hardware store on the bleeder into an old pop bottle.

And be thankful your bleeders didn't twist off (good on you for opening them every few years to bleed the system), because changing those wheel cylinders is a P.I.T.A.

 

In case folks didn't "Get it", this method IS "Gravity bleeding"....
Except that it is faster and also ensures fresh fluid in the caliper bores when done, which opening bleeders, doesn't do.

 

'Not disagreeing with the gravity-bleed method, but it was pretty easy for me to have the wife step on the brake pedal while I cracked the bleeders at each corner...

 

Thanks for the replies everyone.

The gravity bleed method works great on my mountain bikes Shimano brakes. Pull the bleeder valve, let the fluid run like a river for 10 seconds, see fresh fluid, done. Simple and easy.

I've tried it on my car and the flow is abysmally slow. With all four wheels jacked up and the car leveled, a tiny stream of fluid flows out of the passenger rear drum brake even when I removed the bleeder entirely. I stuck a hose into a bottle from the passenger rear bleeder and set a 15 minute minute timer to measure the flow. In 15 minutes the fluid created a thin layer at the bottom of the bottle. At that rate it would have taken HOURS for a single wheel to flush enough fluid to see clear fluid. Unless I wanted to commit an entire day to doing this on every wheel and checking the reservoir (which I don't), this method is far too slow.

I also have a motive power bleeder with the adapter for our cars. I did get it to work three years ago when I did this but it was a nightmare. I ended up needing three C-clamps strategically placed to keep it sealed and I ended up spilling brake fluid all over the frame rail. That was a two day hassle so I didn't do that again this time. Thanks GM engineers for designing the work brake fluid reservoir I've ever seen. My other cars are a one hour service with the power bleeder.

This is what I resorted to, but as I stated in the original post, the rear wheels can only be reached by a socket. Which means you end up taking a bath in brake fluid for the rear wheels.

Thanks JMD. M10x1.5 is what I was looking for.

 

Geezum....bub.

Completely flushing the entire brake system should take about....20 minutes, with no special tools at all. 10 minutes if you know what you're doing (done it before) on a particular vehicle. In a morning meeting, I stated that fact to one of my mechanics who'd told me that it would take all morning (7:30 to noon) to bleed/flush brakes on a Chev Van (where's Fast4355? ). I told him it could be done in 10 minutes, he laughed at me. I asked if he would like me to show him? He did. We went out on the shop floor after the meeting, did the process outlined in post #4, with one additional step* which addresses problematic/slow bleeding brake systems. (Like your car, this van didn't want to bleed the rears, also). I didn't use a stop watch, but we had the system bled/flushed in less than 15 minutes.

It CAN be too slow....but there is are ways around that.

That's a clue (two days to bleed brakes) that something has gone awry. Stand by for explanation...

O.K. So, No "Bath's" necessary**, and I'll give you your two days back. Did you see post #4? Go back and review it.

*When you have a system that is bleeding slowly, WHY IS THAT? If your dinky mountain bike brake circuit can flow fluid rapidly, why isn't the car doing that, with its much larger lines, hoses and orifices? There is a restriction...and 100% of the time, that restriction is "smegma"/sludge that has built up in the system from time and poor maintenance. How do you fix/get rid of it? By blasting the be-geezus out of it to force it through and out of the system. How do you do that? By using the high pressure/high volume "Pressure Bleeder"/hydraulic pump that already comes on the car; the master cylinder. The master cylinder is probably the best brake system bleeding tool I've ever seen or used.

I always gravity bleed all 4 corners at the same time; it's faster, and if you have a slow-flowing corner, you can see that right away by comparing the flow rate of all 4 corners. In this case, I'll close off any/all of the good flowing bleeders, get in the car and hammer the brake pedal a couple times in a row. I get out and inspect the results (old brake fluid) in my catch pan. If there is none, I hammer again until I get copious results. Then? Resume gravity bleed to evacuate air from the corner cylinder that entered when you last released the pedal. If there are other slow/not flowing corners, close the one that you just did, move on to those and repeat. Don't let the master run dry.

Once all the restrictions have been blown through/out, then each corner should finish gravity bleeding the air out in about 30 seconds. Maybe a minute at the most for rear drums, which always seem to flow more slowly than disk/calipers likely due to the proportioning/RPV valve. A secondary benefit of the pedal hammering, is that in the process of blasting the gunk out of that part of the system, you're also rapidly moving a large volume of fresh fluid from the reservoir, down to that corner, so the "flush" part for that corner is already done.

**Finally, what about "Bath time"? Simple. Don't be under the car at the same time that you're blasting on the brake pedal! That solution is nearly automatic since you have to be, you know...IN the car, to pump the brake.

 

Agreed. Two days is a lot with the power bleeder but I had never used it before and was living alone at the time. Day one was 4-5 hours fighting the power bleeder (including a trip to home depot to buy a 8" c-clamp) to get it sealed, flushed, and put back on the ground. Then it was a few hours the next day fixing spots on the frame where the brake fluid missed my towel maze or soaked through and bubbled the paint off due to the poor sealing job my initial attempts made. So it was removing the bad paint, another trip to the store for some spray paint, and some spot repaint for a grand total of two days of work. Which is why I did the two person method this time around and made it an hour job.

Next time I will try what you suggest with some speed bleeders on hand as backup. I find it odd that the two person method and the power bleed method never seems to remove any gunk that is gumming up the lines to improve flow. But if what you say fixes it then I won't complain. Gravity bleeding is the easiest method by far.

 

To Tom's point:

If a wheel, or both rears, won't bleed, it's because the line has a restriction. The most common restriction is, the rubber hose. Those fail by rusting on the inside, where there's a hole that's only about 1/16" through them, to pass the brake fluid; when they rust up in there, the hole gets blocked.

Therefore, if gravity bleeding won't work, it needs AT LEAST that one hose. Given that in most cars, the hoses are all the EXACT same age, have been in there for the EXACT same length of time, with the EXACT same fluid in them, with the EXACT same amount of moisture in it, if ONE has failed that way, they are ALL in pretty much the same state. Swap em ALL out.

This might even help out with uneven brake wear, occasional pulling, etc., by allowing the fluid to be pushed into and back out of, the wheel parts, as it should.

 

The two person method could do it....if the pedal-pumping-person is "getting after it" on the pedal pumping. The pressure bleeder won't do it b/c...what's the pressure? 15 PSI? That ain't gonna do it.

 

I ran into this (rear wheels not bleeding / no fluid flow with bleeder open) on my rear drums 2 years ago. Only on the driver side. When I removed the hard line, fluid flowed readily. Had to replace the wheel cylinder, which solved the problem.

 

What's rusting inside the hose? The fitting? The rest of the hose is not metal....







The orifice where the fluid enders the cylinder was likely plugged or filled with rust,...from? Lack of maintenance.

 

The passenger rear has been like this for at least five to six years in the three times I've tried to gravity bleed the brakes. New wheel cylinders may be in order.

 

Q:

A:

Specifically, the part of it that makes the nipple for the hose to plug onto.

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Now it's been a couple of years but if I remember correctly I placed a box end wrench on the bleeder and with the wrench in place push a clear plastic hose onto the nipple. Loosen the bleeder with the wrench, have the wifey pump the brakes and the old fluid goes out the clear plastic tube and into a plastic pop bottle. When the wifey gets to the bottom of the peddle travel she holds it there, and I tighten the bleeder without removing the clear plastic hose. Repeat until no bubbles are seen leaving the brake cylinder.
You might need a wrench with an offset to get far enough onto the bleeder. If the wrench only slightly grabs, loosen the bleeder with a socket first and once loosened place the box end wrench on.

 

The rear drum brake cylinders are recessed into the backing plate. A standard wrench (and the offset wrenches will not fit into the small area the bleeder is recessed into because the box part is too thick. Official GM service information recommends using a special tool that looks like a socket with a bleeder nipple on the rear end that you can attach a hose to. I've looked for one of those without luck. With standard tools the only way to get on the bleeder nipple is is to use a 5/16 inch deep socket and take a bit of a bath.

 

No bath needed. Don't be under the car while people pumping pedals, is happening. Easy Button.

 

I never got a "bath". Sure, brake fluid got all over the back-plate. Cleaned it off with brake parts cleaner. Really not terribly messy...

 

This is exactly how I did it...wrench, clear hose, pop bottle. Wheel off, worked by reaching over the top. Kept a catch pan under it. Hosed the backing plate off with brake clean when done, drip dry.

Interesting that the OP's '91 has a different design (the '88 is bad enough with it's "clip" to hold the wheel cylinder in place). I didn't keep my '91 long enough to find out. Brakes and clutch were still good. The rear 16" Eagle GA tires on the other hand were showing their wear.

 

Liquids will flow to the lowest point. If all you want to accomplish is a fluid flush just open 1 bleeder at a time and let it flow. Open the bleeder, put a piece of tuning on it and let it flow into a pan, don't let the MC level drop too low. Before doing this suck the MC down with a turkey baster or syringe and wipe it out then refill with fresh fluid.

 

All that was already covered in this thread over a month ago. The "hang up", was when you don't get flow...b/c of an obstruction. Solutions for when that happens were shared as well. Also, no need to waste time doing 1 at a time...do all four at the same time; Git'r dun. Check out POST # 4

 

Aye!
If I were handy with a welder I would fabricate one of those myself.

As things are, I loosen the bleeder screw with a socket, just far enough that I can turn the socket with my fingers.
Then I remove the socket, stuff the hose on the bleeder and open it the final distance by twisting the hose.
Usually letting go of the hose also tightens the bleeder enough for the next go at the brake pedal.