I would like to try the gravity flushing method for flushing the brake lines on my 90 Z. Is there a specific way to do this?. Can I open the rear bleeders first then do the front ones?. Can I do one caliper at a time?, or should they be opened all at the same time?. Will the fluid just run out of the bleeder fitting?. I understand this method is the easiest, most thorough, the least cleanup, and only requires one person (me). Has anyone used this method and can give me the proper procedure for gravity flushing a C4 corvette.
Well I havent done it myself but you have 2 lines that run from the resivour to the abs unit then all the lines that run to the brakes branch off from the abs Im not sure what route the fluid takes but I would imagine it is free flowing...
I just did it , remove all 4 wheels , opened all 4 bleeders....Don't let it run dry in the master cyl.
or you will have to bleed it with 2 people
It takes about a quart of brake fluid and about an hour...my brake fluid is still clean...not sure if it all drains out...but I have clear brake fluid, so it must all drain out to stay clear..
Hi TommyL, I'm not a mechanic, that said I went to sears & bought a Mity-Vac tool. It came with everything you need to do what you want to do. I don't remember how much the tool was but it was less than $50.00. I had very black fluid in my front reservior & the rear reservior was dark. I never used a mity-vac for brake bleeding so I was slow & did things twice because of my lack of experience so it took me about two hours of checking & doing & checking & doing. I know it seems like along time. It came out great though & very easy once I did it I now know it's a snap & I wasted alot of time looking for things that weren't going to go wrong.
My advice would be to get one of these tools and you will not believe how easy it is to suck out all the old fluid & put new fluid in. If you are alone it will take more time than if you have some one looking at the M/C as you are pulling the old fluid out to warn you of the fluid level.
I used the bleeding instructions... Rt. R. then L. R. then Rt. Fr. the L. F. & it was too slow so I did the rear two first, not letting the valve at the bottom of the reservior to get dry. I stopped with just the valve depression filled with old fluid & then I wipped up the crud in the reservior. Put new fluid in that reservior & went & did the same to the front reservior. Then went & did the bleeding sequence after I got new fluid to flow into the catch can from each caliper. The hoses are clear or at least mine were so you can see when you are pulling new fluid. The only thing is the hoses come coiled up so I used my heat gun to relax them, makes them easier to handle. You could plug both ends & put them in hot water it would work.
Sorry this is so long. I just wanted to pass this along in the "if a rookie can do it anyone can" department. Tom
I use a turkey baster and remove as much as possible from the reservoir before I begin the flush, even using a paper towel to wipe up all of residue. On the 93 Z, I have to remove the resevoir, since the design is different and the baster alone wont get to all of the fluid.
I slip a rubber hose over the bleeder and place the other end in a peanut butter jar with an inch of fluid in the bottom. I keep a small "tube wrench" hanging on the bleeder so that I can later tighten it before I remove the hose. I place a mirror on the ground below the drivers door and position it so that I can see the jar. Then I place my shop light on the opposite side of the jar to illuminate the fluid. Then I pump the brakes and add fluid to keep the master cyl. from emptying. When the bubbles stop flowing into the jar, I give it a couple more pumps then I tighten the bleeder and remove the hose.
I have found this works better for me than my Mity-Vac. Tomtom72, I always had probems with the vacuume sucking air into the caliper through the bleeder threads.
My favorite method is pressure bleeding but I haven't yet built a master cyl. cover with an air pressure fitting. I fashioned one for my old muscle car and gave it a few pounds from my air compressor and I got the best pedal yet. Phrogs suggested the Motiv power bleeder. I'm going to check online and see what I can learn about that. Sounds interesting.
I just use the speed bleeders, takes longer to get the tires off and on then it does to bleed the brakes. Losen, pump till clean comes out, tighten and move the to the wheel.
Hi Webgear, Yea, I was unaware about that air thru the bleeder therads thing. Shows how far off the curve I am! The Mity-Vac came with a tube of some kind of lube that the instructions said to put on the hose ends at each connection and to remove the bleeders and coat the threads. I figured "great I just spent $ on a tool that's going to put air in my brakes!"
I followed their instructions and if you have the bleeder cracked just enough and put just enough suction you can actually see when you are getting air from the threads and when you are not. I found if you crack the bleeder too much the air is there and if you tighten a little & pull vac you can see the point at which the air stops and the fluid still flows. It is no where as easy as having a preassure bleeder or a friend to help! But if you are working alone this tool does work if you're careful & willing to adjust it abit. It took me awhile to get the set up right but once I did I was able to get fluid & no air bubbles at all. It sure is not a 15 min. project but I have a hard pedal and no air symptoms and clean fluid... okay it took me an hour but I didn't have another way except bring it to the local chevy dealer. I also didn't know about "speed bleeders". Tom
Location: Oh please Mr. Instructor, move me from the Green to the Black group because I drive so good....BS!!! Durham, NC
Never heard of the Gravity method. Someone has got to be pulling your leg on that one. 1. Go to Sears. But the cheapest sprayer they have. After I bought my Motive Power Bleeder, I saw the same or better sprayer bottle at Sears for $12.. You don't need a big sprayer, the small ones work great. Get another Master Cylinder cap that fits your master cylinder (junk yard, new one, etc), maybe Phrogs has one for you. Go to Home Depot plumbing dept. Buy some fittings and 0 - 20 or 30 lbs pressure guage to bleed of the pressure to the Master Cylinder. Fit the plumbing fittings to the maste cylinder cap. Make sure its sealed, I used JB Weld.
2.Go to a drug store and ask the pharmist for syringes approx 1/2" in diameter. Get a half dozen or so, I get mine for free. They're normally used to administer medicine orally. Use the syringes to suck every last drop of fluid from the master cylinder. Clean out any black residue from the bottom of the master cylinder with some tissues and a screwdriver. Refil the maste cylinder with fresh brake fluid. No need to fill a bottle with one inch of fluid. Just connect a hose to the bleeder. Get a 10mm wrench. Pump up the spayer to 10 lbs pressure, crack the bleeder valve and bleed until clear. I use Castrol SRF, $60/qt for track use as my car gets very, very little street use.
I can bleed all wheels by myself in 45 minutes. Works like a champ.
Do a search in past posts for power bleeders. My buddy Falcon, posted his pictues of his home made power bleeder and he's one THRIFTY person.
Corvette Store
Brake Line Flushing...Gravity Method
