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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / February 2005Vacuum brake bleeding
I was trying to bleed my 95 Cherokee brakes, but the fluid hardly comes out. I thought of vacuum bleeding, but I wonder how much vacuum do I need. I don't have a pump, but can I use my household vacuum cleaner as suction source? I can take a big jam jar, drill 2 holes on the lid to put in the tubes, I already have an adaptor to fit the vacuum hose to the tube. Would there be enough suction to bleed the brakes? Any better ideas apart from spending a whooping $90 on a bleed kit? Pete > I was trying to bleed my 95 Cherokee brakes, but the fluid hardly > comes out. [quoted text clipped - 10 lines] > > Pete Use a pressure bleeder instead, I have found them to be much more reliable. You can probably rig one up with a bigass jar, a Schrader valve (for a wheel) a spare master cylinder cover and some tubing if you don't want to pay for a ready made one. I have a cheap Motive PRoducts one and use the crap out of it. nate  Signaturereplace "fly" with "com" to reply. http://home.comcast.net/~njnagel "You can probably rig one up with a bigass jar, a Schrader valve (for a wheel) a spare master cylinder cover and some tubing if you don't want to pay for a ready made one" Does not work for my car, and most likely not for any newer car that has a cheap plastic brake fluid reservior. Probably work work great on the 1975 Chevy I once had. When I tried to do that it does not work because the cap isn't air tight, therefore no pressure. I use a mightyvac to remove the old fluid from the reservior and then refill and get another person to pump the brakes. It doesn't take long to do it that way because you have already gotten out half the fluid before you start pumping the brakes. > I was trying to bleed my 95 Cherokee brakes, but the fluid hardly > comes out. > > I thought of vacuum bleeding, but I wonder how much vacuum do I need. > I don't have a pump, but can I use my household vacuum cleaner as > suction source? They don't work - I have an A/C vacuum and I've tried different vacuum levels with various Rube Goldberg contraptions on the bleed screws. Other than a pressure bleeder, the next best thing is an assistant sitting in the car pressing the brake petal while you have the bleed screw open. I usually use my wife for this when I do our vehicles and the procedure works well except for a rather annoying whining noise. (from the wife, not the car ;-) Ted Make sure the master is bled first before you try to bleed at the wheels, kinda sounds like this is your problem. If the master is bled you should have plenty of pressure at the bleeders when the pedal is pushed. If you are gravity bleeding & have no pressure, thats a different story. The cheapest pressure bleeder is a 1/16" drill bit & a blow nozzle for your air hose, vacuum systems as I have seen them used (pardon the pun) suck. Put the drill bit thru the MC lid & thru the inside rubber seal at a didderent spot, apply air pressure at a very slow rate (just enough to slightly bulge the resivoiur) with the bleeders of choice open & wait for a puddle. Once started they will usually gravity bleed from there. The new "bleeder hole" in the lid is too small to matter, for all practical purposes, & can be left there with no adverse affects. Good luck. You have got to be kidding right? Brake fluid absorbs water and becomes useless really quick and you are telling someone it is cool to have an open hole in the reservoir? That is a good way to get someone killed! Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's > Make sure the master is bled first before you try to bleed at the > wheels, kinda sounds like this is your problem. If the master is bled [quoted text clipped - 9 lines] > too small to matter, for all practical purposes, & can be left there > with no adverse affects. Good luck. >You have got to be kidding right? > >Brake fluid absorbs water and becomes useless really quick and you are >telling someone it is cool to have an open hole in the reservoir? > >That is a good way to get someone killed! All the brake reservoirs I have seen are all vented. ------------ Alex > >You have got to be kidding right? > > [quoted text clipped - 6 lines] > ------------ > Alex I have never seen a vent going to the fluid compartment! All the fluid would fast piss out. When you hit the brakes fluid squirts up in the air a long ways if the cover is off. Same for hitting bumps. The covers have a vent to allow the inside rubber seal to move down as fluid goes to the calipers or cylinders due to pad wear, but the inside seal is air tight for sure! Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's > They don't work - I have an A/C vacuum and I've tried different vacuum > levels with various Rube Goldberg contraptions on the bleed screws. [quoted text clipped - 6 lines] > > Ted try out speed bleeders. One man brake bleeding, no special tools required. Loosen bleeder, attach hose into jar, pump pedal. Done. Ok, so I still do it two person so I can watch the fluid come out, but it's definitely quicker and less work. Ray > try out speed bleeders. One man brake bleeding, no special tools > required. Loosen bleeder, attach hose into jar, pump pedal. Done. I already tried those, a waste of money. The slightest amount of brake fluid contamination will clog the valve with grit, then the pressure builds up and blows the hose right off the bleed screw. If you want to pay the shipping for the last one of those I bought and try to unclog it you can have it for free. The other problem is the positioning of the bleed screws, never in a good area for attaching a rubber hose to them. not to mention that fluid not only comes out the screw hole but all around the threads of the screw, so you never catch it all. Ted >>try out speed bleeders. One man brake bleeding, no special tools >>required. Loosen bleeder, attach hose into jar, pump pedal. Done. [quoted text clipped - 11 lines] > > Ted You can solve the last problem by removing the bleeders and putting a little Teflon tape on the threads (note: the little hole and the seat area must be kept clear) nate Signaturereplace "fly" with "com" to reply. http://home.comcast.net/~njnagel >>try out speed bleeders. One man brake bleeding, no special tools >>required. Loosen bleeder, attach hose into jar, pump pedal. Done. [quoted text clipped - 11 lines] > > Ted If it's coming out around the threads I think you've got the speed bleeders out too far. IIRC I only loosen them about 1 turn or less - the minimal amount needed. I'd buy them off you... but I only need one more set for the front of the race car... and they probably aren't the ones you have. (There's two types for the front of 70's F-Bods - I need the other ones...) Ray > I was trying to bleed my 95 Cherokee brakes, but the fluid hardly > comes out. I'm curious what "fluid hardly comes out" means. Are you saying the pedal goes to the floor but nothing but air comes out of the bleed nipple? If you remove the bleed screw do you see goop inside? Is the bleed screw blocked with rust? Was the rubber cap missing? Does this happen to ANY bleed screw you try at? Have you done some work to the brakes, such as master cylinder replacement? If so, you may need to bench-bleed the MC first before installing. If lines have been replaced, there can be a surprising amount of air in the system and it may take quite a lot of pumping before you see fluid at the caliper or wheel cylinder. You may just not have bled for long enough. How long did you bleed for and were you using the pedal-push method? SignatureTeGGeR? TeGGer® wrote: >>I was trying to bleed my 95 Cherokee brakes, but the fluid hardly >>comes out. [quoted text clipped - 16 lines] > > How long did you bleed for and were you using the pedal-push method? I've found that on older cars using the pedal-pump method is a good way to end up replacing the MC. Unless it's been meticulously maintained the inside of the MC will be rusty outside the normal travel area of the piston, and wiping the seals over rust will trash them. nate Signaturereplace "fly" with "com" to reply. http://home.comcast.net/~njnagel > I've found that on older cars using the pedal-pump method is a good way > to end up replacing the MC. Unless it's been meticulously maintained > the inside of the MC will be rusty outside the normal travel area of the > piston, and wiping the seals over rust will trash them. > > nate Put a scrap of 2X4 on the floor under the brake pedal, it will act as a stop preventing the MC seals from running into the junk area. > I've found that on older cars using the pedal-pump method is a good > way to end up replacing the MC. Unless it's been meticulously > maintained the inside of the MC will be rusty outside the normal > travel area of the piston, and wiping the seals over rust will trash > them. Agreed. But I've found that even in cars where the fluid's never been changed, you're OK with the pedal-push as long as the car is less than roughly 7 or 8 years old. It's over that when the neglect really seems to take its toll. If the fluid's been changed annually since new using the pedal-push method, the MC will the life of the car. SignatureTeGGeR? TeGGer® wrote: > > I've found that on older cars using the pedal-pump method is a good > > way to end up replacing the MC. Unless it's been meticulously [quoted text clipped - 3 lines] > > Agreed. But I've found that even in cars where the fluid's never been > changed, you're OK with the pedal-push as long as the car is less than > roughly 7 or 8 years old. It's over that when the neglect really seems to > take its toll. > > If the fluid's been changed annually since new using the pedal-push method, > the MC will the life of the car. Less than 7 or 8 years old? I don't think I've ever owned a car that new! (one exception, a car that I bought new, but I other than that I can't remember ever having a car less than 15 years old...) nate >> > I've found that on older cars using the pedal-pump method is a good >> > way to end up replacing the MC. Unless it's been meticulously [quoted text clipped - 18 lines] > new! (one exception, a car that I bought new, but I other than that I > can't remember ever having a car less than 15 years old...) Mine WAS new, in 1991. I always wanted to own a classic and now I only have to wait 6 more years before I have one. The only problem is that when you have a car that's just an "old car", it gets hard contemplating heavy cash outlays for such things as engine rebuilds for a car that's worthless right now and may never be worth anything even when it is an official classic. I'm getting to that stage now. Fix or keep? With 240K, it doesn't need engine work now, but in 3 or 4 years... And then there're those thousands of other little things that eventually go with age. They only cost a few bucks each, but add them all up... SignatureTeGGeR? > Fix or keep? With 240K... Ach! Fix or SELL, I meant to say. Fix or SELL. SignatureTeGGeR? Get a Mityvac hand vac pump (about $25), then make your jar with tubes. Mityvac makes some other options too, including a big reservoir with built-in pump, and an adapter for the bleeder screws. #07400 Put teflon tape on the screw threads so they won't suck air around the threads. To pressure bleed, you really need a pro pressure vessel with a membrane separating fluid and air pressure. Pressurized air over brake fluid forces air and moisture into fluid and ruins it. Most shops no longer use them. It is possible that you vacuum cleaner might pull enough vacuum to get the job done. Worth atry. > I was trying to bleed my 95 Cherokee brakes, but the fluid hardly > comes out. [quoted text clipped - 10 lines] > > Pete |
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