Getting the Air Out |
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cal.bar
Member Joined: 10 Sep. 2016 Location: So. Cal. Status: Offline Points: 767 |
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Posted: 20 May 2019 at 9:38pm |
OK - just finished rebuilding my front axle and am trying to bleed the brakes. (trying being the operative word). When I started, I knew I had air in the lines as it took a few pumps to get the brake pedal firm. So... with my (very disinterested) teen-aged son at the pedal, I opened the right rear bleeder with a hose running to a bottle with brake fluid in it, then had him push the brake all the way down and hold it there until I closed the bleeder valve. Did that 3x until no bubbles in the bottle, and repeated with each line refilling the master cylinder after each wheel. Result? WORSE than before. Almost no pressure in the lines and the pedal was completely spoungy and goes to the floor w/o much effort. Did I need to have him pump it up each time after closing the valves? What am I missing? No leaks that I can detect and the MC is less than a year old. Had perfect brake pressure before I tore it all apart before the axle rebuild.
Edited by cal.bar - 20 May 2019 at 10:47pm |
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TERRY
Member Sponsor Member Joined: 22 May 2007 Location: BOULDER COLORADO Status: Online Points: 3400 |
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Got a leak?
Are the pads adjusted?
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BOULDER 48 2A
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47 deuce alpha
Member Joined: 07 Aug. 2017 Location: Midland Texas Status: Offline Points: 656 |
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You may not have maintained the level in the master cylinder at a high enough level and pumped more air into the brake system. Even if you are getting fluid without bubbles in the catch bottle you could still have air in the line. Before I did anything else I would start over and bleed the brakes again with close attention to the fluid level. 3 pumps of the brake may not be enough to clear out the longest brake line(right rear).
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1947 CJ2A 90419
1947 CJ2A 127735 1949 Ford 8N 1955 Kaiser Willys Pickup Half the distance takes you twice as long. |
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cal.bar
Member Joined: 10 Sep. 2016 Location: So. Cal. Status: Offline Points: 767 |
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OH, true. More pumping. Brand new pads that are well adjusted, so OK on that front. I will start again and pump the hell out of it.
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47 deuce alpha
Member Joined: 07 Aug. 2017 Location: Midland Texas Status: Offline Points: 656 |
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[QUOTE=47 deuce alpha] You may not have maintained the level in the master cylinder at a high enough level and pumped more air into the brake system.
It can be difficult to keep the master cylinder full while you bleed the brakes. If you have an old master cylinder cap you can drill and tap it to use for bleeding. just attach a piece of clear tubing and a funnel and you can watch the level as you pump and bleed. |
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1947 CJ2A 90419
1947 CJ2A 127735 1949 Ford 8N 1955 Kaiser Willys Pickup Half the distance takes you twice as long. |
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cal.bar
Member Joined: 10 Sep. 2016 Location: So. Cal. Status: Offline Points: 767 |
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wow- I don't have an old MC cap sitting around, but that's damned clever. But I'm pretty sure I didn't let the fluid level in the MC fall too low. As I said, I refilled the MC after ever brake line I bled. I never saw it below the 2/3 mark. Still not sure how I failed so badly. Actually WORSE when I finished bleeding than before. I'll try again. |
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67charger
Member Joined: 27 Sep. 2011 Location: Kentucky Status: Offline Points: 1272 |
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If you pump the breaks too hard you could have damaged the rubber plunger on the piston. If you do that it will not build pressure because there is no seal.
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jasonbass
Member Joined: 28 Mar. 2018 Location: little rock ark Status: Offline Points: 261 |
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i always pump brakes 3 times then hold it down onto the floor before cracking the valve. or you can get a "one man" brake bleeder tool at your local auto parts store. its a hand pump that works fairly well
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You have only to believe if you wish to achieve. That rhymed. Unintentional - Rod Kimble
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Rus Curtis
Member Joined: 25 Mar. 2010 Location: Alabama Status: Offline Points: 1733 |
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Definitely pump several times to
build up pressure - doesn't need to duplicate a "panic stop" but
needs to be firm. One push won't build enough pressure to force all the air out. Peddle doesn't move until you secure the screw, so
positive communication really helps. "Pump it up." Thump, thump, thump.
"Okay, ready." Open the bleed screw, watch the stream and close
before the stream stops (see below). "Pump it up." etc,
etc. Working with someone that doesn't do this on a regular basis may
need some gentle coaching. I personally had shifted to closing the
screw before the flow stops (to keep a bubble from back flowing). The
order is furthest to closest. That back rear has a long run and it may be
possible to cavitate in the master cylinder so my preference is to keep the m/c topped off ( the assistant can help watch this through the inspection hole). Right rear, left rear then right front, left front. I also keep
bleeding until the fluid runs clear - even after the bubble. That was then. I was taught how to pressure bleed and won't do it any other way now. |
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Rus Curtis
Alabama 1954 CJ3B Bantam T3-C |
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SteveBonny
Member Joined: 15 Sep. 2018 Location: Waterloo Iowa Status: Offline Points: 103 |
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I second the Motive Products Power Bleeder. Takes all the pain and suffering out of it. I have an old filler cap from a failed master cyclinder I use with teh power bleeder.
I also found that this tool is pretty handy for filling your transmission / transfer case oil.
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47 CJ2A
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Bruce W
Member Joined: 29 July 2005 Location: Northeast Colorado Status: Offline Points: 9649 |
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If you use one of those to fill your transmission/transfer case, it should be labeled and used only for that from then on. NEVER risk getting even a drop of oil of any kind into your brake fluid. It only takes a very little bit of oil to destroy all of the rubber parts in an entire brake system! BW
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It is NOT a Jeep Willys! It is a Willys jeep.
Happy Trails! Good-bye, Good Luck, and May the Good Lord Take a Likin' to You! We Have Miles to Jeep, Before We Sleep. |
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cal.bar
Member Joined: 10 Sep. 2016 Location: So. Cal. Status: Offline Points: 767 |
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WOW - I didn't know that. (not in the manuals)
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RSR_MK
Member Sponsor Member Joined: 22 May 2009 Location: Cabool Mo Status: Offline Points: 657 |
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I agree with Bruce one this one. Cost me around 1,200$$ last year to replace the brake system on a New Holland tractor. Brakes are in the final drive which run in hydraulic fluid so the breaks also use hydraulic fluid. Brake fluid was added to the system to top it off and dissolved the seals in the master cylinder as well as the cylinders in the final drive.
Brake fluid and oil are not enter changeable. Mike |
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Rus Curtis
Member Joined: 25 Mar. 2010 Location: Alabama Status: Offline Points: 1733 |
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Don't mix! Very good advice!
For me, I'm looking at using a screw-on pump to fill gear oil. That way, I can use the original container and dispense under control. Found one at Walmart. Added: I gave bad advice. That
pump above could very well be cheap garbage (in my haste, I grabbed the first image
that popped up on Google). The pump I have is a Quicksilver Marine Gear
Lube Pump. The part number is 802891Q 2. https://www.walmart.com/ip/Quicksilver-8M0072133-Gear-Lube-Pump-Outboard-or-Stern-Drive-3-8-16-Drain-Plug/17165291 (2nd image -w/o metal adaptor) cal.bar's feedback really got my attention. His experience had me doubting my choice. But, since I had this marine pump, I was at
least going to give it a try. On my
first attempt I used it on the rear axle.
The tiny wings on the hose adapter are plastic and wedged into the
filler port and stayed in place when I twisted it into the threads. The GL 4 85-90W Sta Lube pumped very
well. No spills and it emptied the
bottle. I haven't tried it on the gear
boxes yet. Thicker lube may be more difficult. I just wanted to add this in case my post above misleads anyone. Edited by Rus Curtis - 18 July 2019 at 1:15am |
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Rus Curtis
Alabama 1954 CJ3B Bantam T3-C |
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cal.bar
Member Joined: 10 Sep. 2016 Location: So. Cal. Status: Offline Points: 767 |
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Yep. Tried that. You are going to have two problems with that set up. One, the hoses are too short to get into the fill holes if you want/need to keep the container of fluid HIGHER than the fill holes to use gravity to assist. Two, the pump on them is usually too weak to really get much done. You pump and pump and really get no where. I have had MUCH better luck with hand pumps like this: https://www.harborfreight.com/multi-use-transfer-pump-63144.html the hoses are longer allowing you to keep the container above the fill holes and it does pump a larger volume with each pump. BUT, buy two (or 3) as they are also cheap and made in China and are prone to breaking. |
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Red Willy
Member Joined: 18 Mar. 2014 Location: Lake Villa IL Status: Offline Points: 512 |
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Keep in mind, if you pump the pedal to fast you will aerate the fluid. Slow steady pumps until you feel a pressure build up. I have had good luck with gravity bleeding. Open the the bleeder screw and leave it open until you have a solid flow of brake fluid. Topping off as necessary. Do this with all four cylinders. If that doesn’t get all the air out follow up with the pump and bleed.
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Glen
49 CJ3A |
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cal.bar
Member Joined: 10 Sep. 2016 Location: So. Cal. Status: Offline Points: 767 |
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How does gravity bleeding work??? If I open the bleeder valve, the fluid barely trickles out or doesn't come out at all. If I were to pump the brake with the bleeder open, each time I lifted the brake air would be sucked back into the bleeder. |
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Ol' Unreliable
Member Joined: 25 Sep. 2016 Location: CO Springs CO Status: Offline Points: 4226 |
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Have you ever seen the "one-man" bleeder screws with the little check valve in them? You can crack open the bleeder screw and just pump the brake pedal until the fluid is clean or bubbles are gone, whichever. The check valve keeps air from getting in when you let off the pedal. You still need to keep an eye on the MC level. When you're done you just tighten the bleeder screw and go...and stop. That's if you can find the screws, that is. I have no idea where or if they're still available.
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There's a reason it's called Ol' Unreliable
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