86custom Posted September 23, 2012 Share Posted September 23, 2012 My Manche is sick. First off its a 1986 2.5 cyl 4, 5 speed 4x4. When my truck is ideling in nuetral, I step on the brake and the engine starts to stumble and has a rich (exhaust) order. I have done a 91 cherokee dual diafram conversion on the brakes. Also the brakes seem spongey, I recently replaced both front hydrolic hoses and bleed the brakes. When bleeding the brakes, do I do it with the engine on or off? I thought I heard that you are supose to remove the hose on the brake booster. Is this true? Link to comment Share on other sites More sharing options...
Jeep Driver Posted September 23, 2012 Share Posted September 23, 2012 Engine running when bleeding and no you don't remove the vacuum hose. Bleed right rear, then left rear, then right front, then left front. Sounds like a faulty booster.. Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 23, 2012 Share Posted September 23, 2012 I have done a 91 cherokee dual diafram conversion on the brakes. The 91 Cherokee does not have a dual diaphragm booster. Link to comment Share on other sites More sharing options...
Keyav8r Posted September 23, 2012 Share Posted September 23, 2012 Engine running when bleeding? Why? Never heard of bleeding being done this way this before. Link to comment Share on other sites More sharing options...
Jeep Driver Posted September 23, 2012 Share Posted September 23, 2012 The brake booster operates on vacuum supplied by the engine, how on earth would you know if the brakes feel right or not without the engine running? Guys bleed brakes different ways. I've heard of folks gravity bleeding, just open a bleeder and let it drip for 10-15 minutes........not very effective IMO. Others vaccum bleed......I recently bought a vaccum bleeder and have yet to try it.........guess it's about the only real way to do when you have no helper.........I have a wife. I've bled dozens and dozens of brakes on dozens of vehicles over the last thirty years.......always with a helper and always with the engine running. Helper pumps three times....I say "let off".......open bleeder.....say 'to floor'..........close bleeder........'pump'...open bleeder......'to floor'.......close bleeder............ Repeat until air is clear and fluid is clear. Repeat until pedal 'feels' right. Also, if you have rear drums you want to make sure that the rears are adusted correctly after you bleed. Link to comment Share on other sites More sharing options...
Jeep Driver Posted September 23, 2012 Share Posted September 23, 2012 BTW, if your engine stumbles at idle when you step on the brake you are losing vacuum......lots of it. Either hose bad or the bladder in the booster is torn. The comment of the faulty booster seemed to get glossed over. Link to comment Share on other sites More sharing options...
ParadiseMJ Posted September 23, 2012 Share Posted September 23, 2012 Engine running when bleeding? Why? Never heard of bleeding being done this way this before. I've done alot of brake bleeding, speed bleed, gravity bleed, power bleed, regular bleed. Never heard of doing it when the engine running. But I've never seen a Unicorn either. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted September 23, 2012 Share Posted September 23, 2012 Engine running is a croc of crap. You have a vacuum leak and that is contributing to the spongy brakes. Link to comment Share on other sites More sharing options...
Eagle Posted September 23, 2012 Share Posted September 23, 2012 The brake booster operates on vacuum supplied by the engine, how on earth would you know if the brakes feel right or not without the engine running? What difference does it make how they feel while you're bleeding? I've been at this for more than fifty years and I've never heard of anyone bleeding the brakes with the engine running. Not ever. If they're soft, they'll be soft with the engine off, and if they're hard they'll be hard. The point is to get the air out, and you have much better feel for what's happening under your foot without the vacuum booster "helping." Also, if you have rear drums you want to make sure that the rears are adusted correctly after you bleed. Actually, you want the drums adjusted BEFORE you bleed, otherwise excess travel in the shoes may feel like a spongy peddle when it isn't. I agre with JeepCO -- the OP has a vacuum leak. Link to comment Share on other sites More sharing options...
86custom Posted September 24, 2012 Author Share Posted September 24, 2012 What difference does it make how they feel while you're bleeding? I've been at this for more than fifty years and I've never heard of anyone bleeding the brakes with the engine running. Not ever. If they're soft, they'll be soft with the engine off, and if they're hard they'll be hard. The point is to get the air out, and you have much better feel for what's happening under your foot without the vacuum booster "helping." Actually, you want the drums adjusted BEFORE you bleed, otherwise excess travel in the shoes may feel like a spongy peddle when it isn't. I agre with JeepCO -- the OP has a vacuum leak. A vacumn leak in the booster? My pedal is hard with the engine is off. And now that you have mentioned it I do here a possible air leak inside the cab when I push on the brake. Link to comment Share on other sites More sharing options...
86custom Posted September 24, 2012 Author Share Posted September 24, 2012 Thank you every one for your help in this matter. You are awsome. Link to comment Share on other sites More sharing options...
NotMatt Posted September 24, 2012 Share Posted September 24, 2012 I've always bled brakes with the engine off. Does not take much force to get all the air out, you don't need the booster's extra power for that. And the brake "feel" is moot... you know they're bled when it stops spitting air out the bleeder, not when the pedal feels "right". And yes, 86custom I would be suspect of the new booster you put on... or the line going to the manifold. You need to have that connected, don't disconnect it to bleed the brakes. Check over the lines real well and make sure you don't have any splits, cracks, etc... and if that comes out then the "new" booster you put on is probably bad internally. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted September 25, 2012 Share Posted September 25, 2012 If you hear a "air" (vacuum) leak when depressing the pedal, the booster is leaking out Link to comment Share on other sites More sharing options...
opsled Posted September 25, 2012 Share Posted September 25, 2012 If you hear a "air" (vacuum) leak when depressing the pedal, the booster is leaking out I hate when that happens. opsled Link to comment Share on other sites More sharing options...
JeepcoMJ Posted September 25, 2012 Share Posted September 25, 2012 Yep...like when I drilled a hole into mine on the 3800 when mounting the auxillary fuse box Link to comment Share on other sites More sharing options...
mountainman Posted September 25, 2012 Share Posted September 25, 2012 It becomes habit to bleed with the engine running because most cars techs will work on have ABS. The module needs power to have all the pistons in operating position. So when bleeding old cars or trucks like we have, with NO abs.. your fine to do it with engine off. But it doesnt hurt to do it with it running. Either way is fine. I have grown accustomed to engine running with anything that has a booster. Link to comment Share on other sites More sharing options...
Naterenfo1 Posted September 26, 2012 Share Posted September 26, 2012 I always bleed the brakes with the engine running? Haven't hurt anything yet! Link to comment Share on other sites More sharing options...
86custom Posted September 27, 2012 Author Share Posted September 27, 2012 What year came with the dual diaphragm booster. I can't remember what year I got mine off of. I guess I will be junk yarding Saturday. Link to comment Share on other sites More sharing options...
opsled Posted September 27, 2012 Share Posted September 27, 2012 Yep...like when I drilled a hole into mine on the 3800 when mounting the auxillary fuse box That SSSSSSSSSSSSSSSSSSucked...... opsled Link to comment Share on other sites More sharing options...
ComancheKid45 Posted September 28, 2012 Share Posted September 28, 2012 What year came with the dual diaphragm booster. I can't remember what year I got mine off of. I guess I will be junk yarding Saturday. 95+ XJs and all WJs are what are swapped the most. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted October 10, 2012 Share Posted October 10, 2012 That SSSSSSSSSSSSSSSSSSucked...... opsled LOL Link to comment Share on other sites More sharing options...
1989 Eliminator Posted July 9, 2013 Share Posted July 9, 2013 Here is some pictures from my 1989 Manual... Link to comment Share on other sites More sharing options...
coyote kid Posted July 11, 2013 Share Posted July 11, 2013 i bleed with engine running Link to comment Share on other sites More sharing options...
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